Extreme snowstorms

The northeastern USA has just experienced a fairly intense snowstorm that has seen more than 20 inches of snow fall in Boston. There have been a couple of interesting articles about this. Eric Holthaus points out that this is just another sign of global warming and Nate Silver does an analysis for New York and shows that, although the total amount of snowfall hasn’t changed much, the number of days on which it has snowed has reduced; concluding that this indicates an increase in the intensity of the precipitation when it does happen.

There’s also the standard pushback against these links between extreme events and global warming – in which Roger Pielke Jr appears to insult Nate Silver. One problem I have with most of these pushbacks is that they’re typically associated with rather simplistic interpretations of past data. The increase in the intensity of extreme precipitation events is something that we expect to see in a warmer world and is – in a sense – an aspect of physical climatology that is understood quite well.

In a warmer world, the atmosphere can hold more water vapour. This is essentially the Clausius-Clapeyron relation. Additionally, in a warmer world, we expect the evaporation rate to increase. If the rate at which we add water vapour to the atmosphere increases, then the rate at which it falls out of the atmosphere has to also increase. Additionally, we don’t expect this to increase precipitation uniformly; we expect it to predominantly increase the intensity of extreme events.

So, even if we can’t specifically attribute this snowstorm to anthropogenic global warming (something that I suspect is probably virtually impossible to actually do anyway) the increase in the intensity of extreme events is what we would expect under increased anthropogenic forcings. I even did a Google Scholar search for trends in extreme precipitation and found this paper (Kunkel et al. 2013) which says

There is strong evidence for a nationally averaged upward trend in the frequency and intensity of extreme precipitation events.

I accept that this is (I think) for the whole US, not just the North East, but it is consistent with what we’d expect under increased anthropogenic forcings. Eric Holthaus’s article also links to a resource that says

The Northeast has experienced a greater recent increase in extreme precipitation than any other region in the United States; between 1958 and 2010, the Northeast saw more than a 70% increase in the amount of precipitation falling in very heavy events (defined as the heaviest 1% of all daily events)

Both Eric Holthaus’s and Nate Silver’s articles also point out that there is a temperature sweetspot for snowfall (between -7oC and ooC). Therefore, we could see increased precipitation in a warmer world, but a reduction in snowfall if winter temperatures are less often – in future – in the optimal range for snowfall.

So, the point I’m trying to get at is that an increase in the intensity and, possibly, frequency of extreme precipitation events is something that we expect under increased anthropogenic forcings. The physical processes involved are also well understood, and it would be extremely surprising if the climate didn’t behave in this way. Additionally, there is already evidence for an increase in the frequency and intensity of these extreme events. So, those who want to downplay the link between global warming and these events should probably at least take this into account when doing so; if they want to be taken seriously that is. I guess, in my view, context is important. Others may, of course, disagree.

Update : I had a brief chat with Mauri Pelto on Twitter, which made me realise that I should clarify something. The issue here is not the storm itself, but the precipitation. So, the suggestion is not necessarily that AGW has made the storm more intense (measured by wind speed, for example), but that anthropogenic influences have increased the amount of available water vapour and hence makes intense precipitation events more likely.

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151 Responses to Extreme snowstorms

  1. Michael Lloyd says:

    Mark Lynas has a recent article on this subject showing data for the UK.

    http://www.marklynas.org/2014/12/have-we-been-breaking-more-and-more-weather-records/

  2. KarSteN says:

    Pielke has yet to learn that the answer one gets always depends on how the question is framed. Based on observations, there is no way answering the question whether climate change has changed the odds of winter storm (or any other rare event for that matter) to occur more or less frequent. Rather you’ve got to do large ensemble simulations with and without anthropogenic forcing to get the right answer, and in this case the answer would likely be that winter storms become more severe (at least in terms of precipitation). It is more difficult to answer the question whether they’re also becoming more frequent, but that doesn’t mean it isn’t possible. What Pielke can’t do, however, is to claim that there is no link between these types of storms and climate change. Of course that won’t stop him doing just that.

  3. Joshua says:

    From RPJr….

    “But if these folks really wanted to contribute to scientific understandings they should seek to publish their alternative theories in the peer reviewed literature.”

    I’m surprised to see that he thinks that if something is peer-reviewed, it “can’t” be criticized.

    Richard Tol is going to be very concerned about Roger.

  4. Joshua says:

    =>> “What Pielke can’t do, however, is to claim that there is no link between these types of storms and climate change. Of course that won’t stop him doing just that.”

    I have asked Roger directly whether his acceptance of AGW means that he agrees that extreme weather will increase…but that he’s only questioning whether any signal exists as of yet…

    IIRC he didn’t give (avoided?) a direct answer but implied that he does agree and then said that i should read his book.

  5. Chic Bowdrie says:

    “So, the point I’m trying to get at is that an increase in the intensity and, possibly, frequency of extreme precipitation events is something that we expect under increased anthropogenic forcings.”

    I follow the logic that an increase in atmospheric water vapor MAY contribute to extreme precipitation and, by similar logic, anthropogenic forcings MAY contribute to global warming. Unfortunately, proof that an incremental increase in CO2 causes warming has yet to be verified. IOW, allegedly extreme precipitation events MAY be caused by factors other than anthropogenic forcings.

  6. John Hartz says:

    KarSteN: You state:

    Pielke has yet to learn that the answer one gets always depends on how the question is framed.

    I believe Pielke Jr. learned that lesson years ago and very adroitly applies it in his analyses. Pielke is first and foremost a propagendist and secondarily an academician.

  7. Chic,

    Unfortunately, proof that an incremental increase in CO2 causes warming has yet to be verified.

    It really has been verified. You should be cautious about any site, or source, that suggests otherwise.

  8. If the atmosphere is warmer, physics says it sucks up more water from wherever it can get it. Physics also says that what goes up, must come down. Therefore it follows that precipitation has to increase, though where and how it falls might vary in timing, duration and location.

    So it seems to me that anyone who denies our weather is changing yet accepts that the planet is warming, has a lot of explaining to do. It’s not just a case of gainsaying the published science, they have to justify their opinion with alternative evidence or convincing interpretation of existing evidence. Or is this too simplistic?

  9. Joshua,

    but that he’s only questioning whether any signal exists as of yet…

    Yes, that does appear to be what he does. However, if you look at what he shows, it was data showing no increase in the number of extreme storms and a quote from a paper saying no increase in the amount of snowfall. Firstly, noone said there should necessarily be an increase in the number of storms, it was about the intensity of the storms (and Nate Silver’s anaylsis suggested a decrease in the number of snowstorms). Secondly, there seems to be ample evidence that there’s been an increase in the intensity and frequency of extreme precipitation events in the north east. Pielke Jr’s quote refers only to snowstorms, not to precipitation events in general. Given that warming could reduce the fraction of precipitation falling as snow, an increase in intensity and frequency overall could still be consistent with little change in the amount of snowfall, but an increase in the intensity of extreme snowstorms when they happen. That’s my understanding at least.

  10. A comment I meant to write on this post, but forgot, was about a possible conundrum those who want to minimise the impact of global warming might face. One way that we could warm without increasing the evaporation rate is if the relative humidity were to rise to prevent the evaporation rate from increasing. However, this would imply even more water vapour in the atmosphere, an even larger feedback response, and enhanced warming. Alternatively, if you want to argue that the water vapour feedback will be low, you’re essentially arguing for a reduction in the relative humidity as we warm. This, however, would suggest an even greater increase in evaporation rate, and hence an even greater increase in precipitation. At least, I think that’s right.

  11. izen says:

    @- Chic Bowdrie
    ” Unfortunately, proof that an incremental increase in CO2 causes warming has yet to be verified. ”

    Proof is confined to Mathematics and liquor.

    What evidence do YOU think would verify the claim made by all mainstream, and most of the fringe, science that CO2 causes warming?

    @-“IOW, allegedly extreme precipitation events MAY be caused by factors other than anthropogenic forcings.”

    Gremlins?

  12. Joshua says:

    ===> “in which Roger Pielke Jr appears to insult Nate Silver.”

    I find it interesting that IMO, in the past Roger has been quite willing to imply – under a transparent cloak of plausible deniability – that climate scientists knowingly promote bad science for the purpose of pushing an agenda and/or for personal gain..

    But when talking about Silver, what we get from Roger is that “smart” “amateurs” are worth listening to, and if they’re journalists they shouldn’t get confused about what’s in peer-reviewed and IPCC literature.

    Why, with Silver, does Roger tone down the thinly veiled impugning of motivations and integrity?

  13. t0kodave says:

    ATTP. You are exactly right. There are a couple figures in here: http://nca2014.globalchange.gov/ that detail the extent of increased intense precipitation events…and many more at other sites with a little searching…

  14. Joshua says:

    Anders –

    In this excerpt

    “However, if you look at what he shows, it was data showing no increase in the number of extreme storms and a quote from a paper saying no increase in the amount of snowfall. Firstly, noone said there should necessarily be an increase in the number of storms,…”

    I notice that in the first sentence you refer to “extreme storms” and in the second you refer to “storms” sans “extreme.”

    This is all a bit tough for me to follow. So with the caveat that I’m just a dumb troll trying to understand, and who might just be showing once again (in case anyone doubted it previously) just how dumb I am

    … Depending on your measurement methodology, it would seem to me that saying that storms will be more intense is kind of the same thing as saying that the number of extreme storms will increase: The distinction between those two ways of talking about the change over time revolves around what cut-off point you use to determine what is or isn’t “extreme” – which is basically arbitrary.

    Depending on the cut-off, if the intensity of storms increase generally, storms X, Y, and Z which previously fell just below the inclusion criterion would now be pushed above that level so as to be included? Thus, more intensity should = more extreme storms? But that could come along with fewer or no change in number of storms overall (meaning the sum of non-extreme storms plus extreme storms).

    ==> “Secondly, there seems to be ample evidence that there’s been an increase in the intensity and frequency of extreme precipitation events in the north east. Pielke Jr’s quote refers only to snowstorms, not to precipitation events in general. Given that warming could reduce the fraction of precipitation falling as snow, an increase in intensity and frequency overall could still be consistent with little change in the amount of snowfall, but an increase in the intensity of extreme snowstorms when they happen. That’s my understanding at least.”

    Yeah. That seems interesting to me. It’s too bad that I can’t think of anywhere on the Interwebs where I might be able to read a discussion about that as opposed to sameolsameol identity politics dressed up as a discussion of climate – except maybe if Pekka shows up here, but in which case I probably won’t be able to follow the discussion.

  15. Joshua says:

    Anders –

    In this excerpt

    “However, if you look at what he shows, it was data showing no increase in the number of extreme storms and a quote from a paper saying no increase in the amount of snowfall. Firstly, noone said there should necessarily be an increase in the number of storms,…”

    I notice that in the first sentence you refer to “extreme storms” and in the second you refer to “storms” sans “extreme.”

    This is all a bit tough for me to follow. So with the caveat that I’m just a dumb tr*ll trying to understand, and who might just be showing once again (in case anyone doubted it previously) just how dumb I am

    … Depending on your measurement methodology, it would seem to me that saying that storms will be more intense is kind of the same thing as saying that the number of extreme storms will increase: The distinction between those two ways of talking about the change over time revolves around what cut-off point you use to determine what is or isn’t “extreme” – which is basically arbitrary.

    Depending on the cut-off, if the intensity of storms increase generally, storms X, Y, and Z which previously fell just below the inclusion criterion would now be pushed above that level so as to be included? Thus, more intensity should = more extreme storms? But that could come along with fewer or no change in number of storms overall (meaning the sum of non-extreme storms plus extreme storms).

    ==> “Secondly, there seems to be ample evidence that there’s been an increase in the intensity and frequency of extreme precipitation events in the north east. Pielke Jr’s quote refers only to snowstorms, not to precipitation events in general. Given that warming could reduce the fraction of precipitation falling as snow, an increase in intensity and frequency overall could still be consistent with little change in the amount of snowfall, but an increase in the intensity of extreme snowstorms when they happen. That’s my understanding at least.”

    Yeah. That seems interesting to me. It’s too bad that I can’t think of anywhere on the Interwebs where I might be able to read a discussion about that as opposed to sameolsameol identity politics dressed up as a discussion of climate – except maybe if Pekka shows up here, but in which case I probably won’t be able to follow the discussion.

  16. John Hartz says:

    One of the tasks I undertake for SkS is assembling the Weekly News Roundups. While perusing articles about the connection between this week’s snow storm in the Northeast U.S. and manmade climate change, I came across one explanation that seems to different than the others. It is contained in:

    Unprecedented Ocean Heat off East Coast is Fueling the Historic Hurricane Force Blizzard by FishOutofWater, Daily Koss, Jan 26, 2015

    Is FishOutofWater’s analysis sound? Is it consitent with Nate Silver’s analysis? Eric Holthaus’s?

  17. John Hartz says:

    All of the MSM articles that I have come across on thois topic seem to focus on Atlantic storms which have made landfall on the Northeast coast of the U.S. and Canada. Shouldn’t a robust analysis of trends be based on the universe of all stroms in the north Atlantic including those that did not make landfall?

  18. Willard says:

    Since I’m in a philosophical mood, honest broker stuff on this matter relies on a conflation between types and tokens:

    http://en.m.wikipedia.org/wiki/Type%E2%80%93token_distinction

    Since climate science ain’t deterministic on specific events, it’s easy for honest brokers to whine against those who should know better than explain them using AGW. On the other hand, once we point out that specific events belong to certain types, their argument peters out a bit. In any case, all this can only be settled using hypothesis testing, which requires lots of specific events.

    In other words, AT’s claim that the explanation of specific events may always escape us seems to hold. On that matter, he agrees with Aristotle.

  19. Marco says:

    ATTP, Chic has history, including on this site. I don’t think you want to go into circles once again, with Chic just saying “I don’t believe it, it is all too uncertain, you don’t have any evidence” (that’s what his arguments consistently come down to – see also http://scienceblogs.com/stoat/2014/02/16/the-idealised-greenhouse-effect-model-and-its-enemies/).

  20. John Hartz says:

    Because this week’s N’eastener snowstorm did not hit the New York city area as hard as had been predicted by the National Weather Service, the MSM has been busy playinbg the blame-game. The following article explains how the official forecast got it wrong for NYC.

    Why (Almost) Everyone Got Snowpocalypse Wrong by Cliff Weathers, Alternet, Jan 27, 2015

  21. John Hartz says:

    Cliff Weathers concludes his Alternet article cited above with the following:

    Keep in mind that meteorology is a unique science, probably the only one where scientists are producing a new theory every day. Weather patterns can still be baffling for meteorologists, by their own admission. They understand that the atmosphere in any given place can be capricious and unstable by the minute. And as they explain, any tiny disturbance below the limits of their observations can grow or alter larger weather systems in just a short period of time. That’s why more “high-definition” prediction models like the new GFS will improve weather prediction in the near future.

    This statement suggests to me that “Weatherball” should be recognized as a game in its own right.

  22. tokodave,
    Thanks.

    Joshua,

    But when talking about Silver, what we get from Roger is that “smart” “amateurs” are worth listening to, and if they’re journalists they shouldn’t get confused about what’s in peer-reviewed and IPCC literature.

    Maybe I misread his comment about Nate Silver, but I interpreted his minority and amateur as being somewhat snarky. His implication appears to be that Nate Silver is ignoring the literature. However, all that Silver does is show that the amount of snow hasn’t changed much, but the number of snowfall days has decreased, hence the individual events have been more intense. Pielke Jr. appears to rebut this by quoting something saying that the amount of snowfall hasn’t increased, which is what Nate Silver, himself, said. So, not only is his analysis pretty simple (so could easily shown to be wrong if it is) it doesn’t appear inconsistent with the literature.

    Also, this article from Mauri Pelto shows 7 of the 10 largest snowfall events – since 1893 – have been since 1992.

  23. Joshua,

    I notice that in the first sentence you refer to “extreme storms” and in the second you refer to “storms” sans “extreme.”

    Yes, the figure had both storms and extreme storms. Neither had increased.

    Depending on your measurement methodology, it would seem to me that saying that storms will be more intense is kind of the same thing as saying that the number of extreme storms will increase: The distinction between those two ways of talking about the change over time revolves around what cut-off point you use to determine what is or isn’t “extreme” – which is basically arbitrary.

    I think this is probably roughly right, although it is technically possible to increase the intensity of extreme storms without increasing their frequency (by changing the distribution).

    I also want to clarify something. If you consider the paper that Pielke Jr uses (Hirsch et al. (2001)) it’s actually referring to the storms, not the precipitation. So, the Figure (Fig. 5) is – I think – wind speed. But what’s being discussed here is the intensity of the precipitation. Given that that is related to the amount of water vapour available – and not to the intensity of the storm itself – that the storm intensity hasn’t increased does not mean that the precipitation hasn’t increased.

  24. Joshua says:

    ==> “Maybe I misread his comment about Nate Silver, but I interpreted his minority and amateur as being somewhat snarky. ”

    I agree it was snarky. But I think it fell short of the more aggressive insinuations about motivations that he frequently makes about climate scientists (i.e., that they are corrupting their science to pursue an agenda or personal advancement). I’m not doubting that he was being insulting, just questioning if there’s a difference (and wondering a bit why that difference might exist)

  25. John,

    Is FishOutofWater’s analysis sound? Is it consitent with Nate Silver’s analysis? Eric Holthaus’s?

    I don’t know specifically, but it seems fine. The warmer SSTs means more energy for the storm itself and if it’s pulling in warmer air, then more water vapour to produce the more intense precipitation.

  26. Joseph says:

    The increase in the intensity of extreme precipitation events is something that we expect to see in a warmer world and is – in a sense – an aspect of physical climatology that is understood quite well.

    I agree with the others, Roger will never talk about the known effects getting much worse in the future due to climate change (as the temps go up), especially if we continue BAU. Even though he supposedly accepts the basic science.

  27. izen says:

    Here is the warm water coming up from the Bermuda Triangle…

    http://earth.nullschool.net/#current/ocean/surface/currents/overlay=sea_surface_temp/orthographic=-58.89,40.57,825

    Here is the wind and temperature just at or aboce the surface.

    http://earth.nullschool.net/#current/wind/isobaric/1000hPa/overlay=temp/orthographic=-58.89,40.57,825

    That blue tongue of cold is driven by a loop in the jet stream, try cliking on the EARTH menu on The nullschol page and select 500hPa (about everest/jetstream altitude) and MSLP, the surface air pressure.

    The extreme weather is the product of the cold low meeting the warm ocean high?.

  28. Joseph says:

    One question I had was whether increased temperatures would necessarily make droughts more intense on average? I think I have heard something to that effect before.

  29. Chic Bowdrie says:

    [Mod : Sorry, Chic, but we’ve been through this all before and I don’t have the energy, or interest, to do so again.]

  30. Frank says:

    ATTP wrote: “In a warmer world, the atmosphere can hold more water vapour. This is essentially the Clausius-Clapeyron relation. Additionally, in a warmer world, we expect the evaporation rate to increase. If the rate at which we add water vapour to the atmosphere increases, then the rate at which it falls out of the atmosphere has to also increase. Additionally, we don’t expect this to increase precipitation uniformly; we expect it to predominantly increase the intensity of extreme events.”

    The situation is somewhat more complicated than you indicate. According to models, precipitation will increase far less than expected according to the C-C equation (7%/degC). Check out this graph from Isaac Held’s blog. However, the Wentz (2007) indicates that observed increase in precipitation has been about 7%/degC, so models may be wrong.

    http://www.gfdl.noaa.gov/blog/isaac-held/2014/11/15/52-warming-and-reduced-vertical-mass-exchange-in-the-troposphere/

    If evaporation increases 7% for a 1 degC rise in SSTs and latent heat flux is currently about 80 W/m2, that represents a 5.6 W/m2 flux. Given that the lower atmosphere over the oceans warms about as fast as the surface, the increase in both OLR and DLR is similar. This creates a surface energy balance dilemma, which Isaac Held describes below:

    http://www.gfdl.noaa.gov/blog/isaac-held/2014/06/26/47-relative-humidity-over-the-oceans/

    Like any heat engine, the energy a storm can extract from warmer oceans depends on the DIFFERENCE between SST and temperature at the top of the convective column. Increasing humidity reduces the lapse rate. Given that storms often develop at the intersection of a cold upper air mass and warm lower air masses, Arctic amplification will reduce the energy available to such storms.

  31. Willard says:

    I follow the logic that smoking MAY kill, and by similar logic, smoking companies MAY contribute to disinformation campains. Unfortunately, proof that smoking kills has yet to be verified. Allegedly lung cancer MAY be caused by factors other than smoking.

    The only certainty is Grrrowth. Only Grrrowth can save us.

    Thank you.

  32. The physics approach to framing the issue is to ask whether there has ever been a phenomena where if the energy of the system increased, then the statistical variance of some measure proportional to energy decreased. As N goes the variance goes as N (standard deviation=Sqrt(N)) according to statistical mechanics

    I can’t think of one and I have been contemplating this for a while now.

    The possible exception to this is in a specially-engineered compensation or feedback-control system.

  33. BBD says:

    izen

    Thanks for the link to the Earth.nullschool model. I do love a good data visualisation tool and this is a corker!

    🙂

  34. izen says:

    Here is a rough animation of the last three days of weather over the US East coast. Wind is at the 850hPa level, about 1 Km up or low cloud level?

  35. Frank,
    I’m not entirely sure what you’re suggesting. I haven’t had a chance to read those links in detail, but they do seem to show the water vapour content and evaporation rate increasing as we warm. I realise that there are complications related to convection, etc, but that doesn’t invalidate that basic point. I wasn’t suggesting that my explanation was complete 🙂

  36. Rachel M says:

    OT sorry but VOTE 1 andThenTheresPhysics best topical weblog:
    http://2015.bloggi.es

  37. izen says:

    Woops,
    Got the acknowledgements wrong on the animation.

    http://earth.nullschool.net/about.html

    Are the source, if you have not played around with their visualization tool before, and your browser and web-link allows it, I can strongly recommend this source of information, apart from the scientific interest, and the utility for seeing the big picture at least of what weather is coming, it is very, VERY beautiful!

    http://earth.nullschool.net/#current/wind/isobaric/250hPa/atlantis=47.84,94.36,440

    (okay so maybe thats a bit garish… -grin-)

  38. Frank says:

    FWIW, Boston was hit by a similar snow storm in 1978, which caused all roads in Massachusetts and Connecticut to be closed for 3 days and roads in around Boston to be closed for 5 days (one whole work week). Or you can check out the Blizzard of 1888 with 40-60 inches of snow. Or the 10 worst blizzards at the link below. Looking at the death tolls in the ten worst blizzards, the important news (IMO) is how well we have adapted to severe winter storms – whether they are increasing in number or severity or not. Better weather forecasts are keeping people indoors and not stranded on roads. Governments are better prepared to deal with the problem.

    http://en.wikipedia.org/wiki/Northeastern_United_States_blizzard_of_1978
    http://en.wikipedia.org/wiki/Great_Blizzard_of_1888
    http://www.livescience.com/31880-countdown-10-worst-blizzards.html

    Snowfall totals can be somewhat misleading since one inch of rain can produce from less than one foot of wet snow (when temps are near freezing) to more than two feet of power (when temps are well below freezing).

  39. Frank,
    Again, I’m not quite sure what your point is. Noone is claiming these events haven’t happened before.

    Snowfall totals can be somewhat misleading since one inch of rain can produce from less than one foot of wet snow (when temps are near freezing) to more than two feet of power (when temps are well below freezing).

    In a sense that is related to the point I was making. There is a physical expectation that we’ll see an increase in the frequency and intensity of extreme precipitation events. There is also evidence to support this. That would imply that snowstorms and other precipitation events – in a warmer world – will have a greater tendency to be extreme than was the case in the past. However, it’s overall precipitation that we expect to increase, not necessarily snowfall as that will depend on the likelihood of the temperatures being optimal. However, if snowfall does happen, it will still have a greater tendency to be extreme than was the case before.

  40. Genghis says:

    ATTP, – “anthropogenic influences have increased the amount of available water vapour and hence makes intense precipitation events more likely.”

    Does that mean that anthropogenic influences have increased the amount of clouds?

  41. John Mashey says:

    1) “Both Eric Holthaus’s and Nate Silver’s articles also point out that there is a temperature sweetspot for snowfall (between -7oC and ooC).”

    Experienced skiers are rather familiar with this effect. The sort of huge dumps that hit the Sierras now and then just don’t happen very often when it’s really cold.

    2) I think Frank’s comment addresses the same fact as in hurricane prediction: we are better at doing this … which doesn’t make the fact of the increase in intensity go away, but for developed societies, lessens the deaths, at least. I remember the 1978 blizzard all too well: I was with a bunch of Bell Labs colleagues at conference in Tucson, AZ, where it was sunny, we had bags of oranges. On way back to NJ, we got stuck around Chicago’s O’Hare Airport for 3 days, because the everything from New England out past Chicago was whacked hard.. Worst trip ever, and I’ve probably flown 1M+ miles.
    It’s much nicer to drive or fly to ski slopes where the snow is, than to have it come after you.
    I have zero doubt these storms will get more intense, but I do wish more of the precipitation would come here to CA.

  42. Genghis,

    Does that mean that anthropogenic influences have increased the amount of clouds?

    Yes, changes in clouds is probably a small positive (0 – 1 Wm-2K-1) feedback.

  43. GSR says:

    Anders, an unintended consequence of the malicious attack on your privacy is the highly welcome increase in ATTP activity. The same happened at Hot Whopper.

  44. Rachel M says:

    Is that why there are suddenly so many comments?

  45. izen says:

    @-Genghis
    ” Does that mean that anthropogenic influences have increased the amount of clouds?”

    I will defer to ATTP with the yes, ….
    But (!) the amount of clouds does not vary in a linear or simple relationship with the water vapour content of the atmosphere. Because the temperature change alters the carrying capacity and precipitation point, clouds, which are condensed water vapour may not inevitably increase because the amount of water vapour carried by a volume of air increases. There are other constraints on cloud variability because the generation of clouds and their dissipation are dynamic processes that limit large shifts in amount and type.
    (oh dear, I do hope someone can give a better scientific basis for that claim!)

    Just for added complication, the type of clouds that are generated by warming increasing humidity depend on the site. Increased ocean temperatures, now at historically record levels without any 48% uncertainty nonsense, cause increased low evaporative clouds that cause net warming as ATTP mentions and drive storms to be more extreme.

    one more pretty picture of this from the nullschool source, a couple of storms off Madagascar with the total cloud water overlay.

    http://earth.nullschool.net/#current/wind/isobaric/1000hPa/overlay=total_cloud_water/equirectangular=75.50,-24.06,1200

    When you look at the climate, remember it is looking back at you!

  46. Joshua says:

    Ghengis –

    Is your last name Kahn by any chance?

    If so, like ‘warmists” and “alarmists,” do you warn your victims that you are the punishment of god?

    https://andthentheresphysics.wordpress.com/2015/01/19/matt-ridley-lukewarmer/#comment-45576

  47. Genghis says:

    Joshua – “If so, like ‘warmists” and “alarmists,” do you warn your victims that you are the punishment of god?”

    You do know that it was Genghis’s conquering of the ME that stopped the Muslims from Conquering Europe?

    Should I put up white, red and black tents?

  48. Genghis says:

    ATTP, – Yes, changes in clouds is probably a small positive (0 – 1 Wm-2K-1) feedback.”

    By my actual measurements a 1 percent increase in clouds in the tropics and Subtropics is a 4-5 watt per square meter decrease.

    I gave you the figures and calculations in a previous post.

  49. Genghis,

    By my actual measurements a 1 percent increase in clouds in the tropics and Subtropics is a 4-5 watt per square meter decrease.

    I gave you the figures and calculations in a previous post.

    No, not again! I know you gave them, but they’re not right and we really can’t go through this again.

  50. izen says:

    @-Frank
    “Like any heat engine, the energy a storm can extract from warmer oceans depends on the DIFFERENCE between SST and temperature at the top of the convective column. Increasing humidity reduces the lapse rate. Given that storms often develop at the intersection of a cold upper air mass and warm lower air masses, Arctic amplification will reduce the energy available to such storms.”

    But warmer SSTs will increase it.
    And the energy source is the ocean, a constraint on storm development is the energy available from the water, not just the surface layer but the heat content at depth.

  51. Vinny Burgoo says:

    ATTP: A few things. I haven’t read the last twenty or so comments so don’t know if anyone has already mentioned these.

    1. In what way are the interpretations of the historical data cited by Roger Pielke Jr (Hirsch et al, a couple of others, and whomever was cited in the AR5 chapter Pielke quoted) more simplistic than those favoured by Nate Silver and Kunkel et al? You didn’t get around to explaining that.

    2. Predictions based on physics can’t debunk historical trends. (Well, I suppose they could cast strong doubt on the historical data behind them or on the methods used to derive the trends, but your long What-The-Physics-Says detour never came anywhere near stuff like that.)

    3. Trends in extreme precipitation events say very little about trends in extreme snowstorms. (As it happens, Kunkel et al also covered extreme snowstorms. Their analysis found that there were four times as many extreme snowstorms in the Northeast in the period 1961-2010 compared to 1901-1960 – four in five decades versus one in six. Something tells me you won’t find that analysis simplistic.)

    4. As I understand it, Pielke’s post was a response to Michael Mann, who had been citing (apparently out-of-date) peer-reviewed literature to support his view that the coming winter storm would be driven by climate change. That is why Pielke asked a question that emphasized the peer-reviewed literature.

    5. Silver’s analysis is interesting but, with just 10″ of snow in Central Park, it’s all a bit moot (US sense), innit?

  52. Vinny,

    In what way are the interpretations of the historical data cited by Roger Pielke Jr (Hirsch et al, a couple of others, and whomever was cited in the AR5 chapter Pielke quoted) more simplistic than those favoured by Nate Silver and Kunkel et al? You didn’t get around to explaining that.

    Well, what Pielke Jr quotes doesn’t really refute what the others present. His first is that extreme storms haven’t increased in intensity. Okay, fine, but this is about precipitation, not the storms. He then quotes Hirsch et al. saying snowfall hasn’t increased. Silver said the same but pointed out that the number of snowfall days had decreased, therefore the precipitation events were more intense. So, there’s nothing wrong with what Pielke Jr presented, it just doesn’t seem relevant.

    Predictions based on physics can’t debunk historical trends.

    Except the data supports the physics. There has been an increase in the frequency and intensity of extreme precipitation events.

    Trends in extreme precipitation events say very little about trends in extreme snowstorms.

    Sure, but if the trend in extreme precipitation events is because of warmer air and increased water vapour, then that also makes a more intense snowstorm more likely too.

    As I understand it, Pielke’s post was a response to Michael Mann, who had been citing (apparently out-of-date) peer-reviewed literature to support his view that the coming winter storm would be driven by climate change. That is why Pielke asked a question that emphasized the peer-reviewed literature.

    Possibly, but that wasn’t obvious from his post. Both of the links he provided were to articles talking about extreme precipitation which he called minority views and which he tried to debunk by talking about the storm strengths (wind speed) rather than precipitation itself (which has increased in frequency and intensity according to the evidence available).

    Silver’s analysis is interesting but, with just 10″ of snow in Central Park, it’s all a bit moot (US sense), innit?

    I don’t know about moot, but it’s just New York so somewhat localised.

  53. izen says:

    @-Genghis
    “You do know that it was Genghis’s conquering of the ME that stopped the Muslims from Conquering Europe?”

    Revisionist history as well!

    An alternative view might be that the Muslim civilisation, a literate and scientifically developed culture was lucky in having the civic organisation and military skills to defeat a marauding migration of illiterate nomadic pastoralists. And stopping the Mongols. Who decimated Russia and China instead.

    Thereby preserving the classical Greek and Roman knowledge for the rest of Western Europe to exploit in later centuries instead of recovering from repeated genocidal occupation.
    Use a search engine to look up the career of Baibars, 13th-century Mamluk Sultan of Egypt.
    Who not only stopped the Mongols from overrunning the most advanced culture of the region but also kept a bunch of religious fundamentalists from vandalising the region more than they already had by eliminating Louis IX.

  54. Steven Mosher says:

    for the too lazy to click crowd

    “Many studies have looked at average snowfall over a season in climate models, but there’s less known about these very heavy snowfalls,” says study author Paul O’Gorman, an associate professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “In some regions, it is possible for average snowfall to decrease, but the snowfall extremes actually intensify.”
    O’Gorman studied daily snowfall across the Northern Hemisphere using 20 different climate models, each of which projected climate change over a 100-year period, given certain levels of greenhouse gas emissions. He looked at both average seasonal snowfall and extreme snowfall events under current climate conditions, and also following projected future warming.
    Not surprisingly, O’Gorman found that under relatively high warming scenarios, low-elevation regions with winter temperatures initially just below freezing experienced about a 65 percent reduction in average winter snowfall. However, in these same regions, the heaviest snowstorms became only 8 percent less intense. In some higher-latitude regions, extreme snow events became more intense, depositing 10 percent more snow, even under scenarios of relatively high global warming.
    “You might expect with a warmer climate there should be major changes in snowfall in general,” O’Gorman says. “But that seems to be true to a greater extent for average snowfall than for the intensities of the heaviest snowfall events.”
    O’Gorman has published the results of his study this week in the journal Nature.
    Daily snowfall
    For the most part, researchers have only been able to analyze snowfall on a seasonal scale, estimating a winter’s average snow amounts with climate change. Such analyses, while useful, only paint a broad picture of snowfall’s response to global warming, and may miss specific events, like a large blizzard that may occur over a day or two.
    Daily snowfall in a range of climate model simulations has recently been made available through the Coupled Model Intercomparison Project — a growing archive of climate modeling output, including snowfall, that modeling centers and researchers around the world contribute to and analyze.
    O’Gorman analyzed daily snow amounts from simulations with 20 different climate models in the archive. Each model simulated a “control climate,” for the years 1981 to 2000, as well as a “warm climate,” for the years 2081 to 2100, assuming relatively high emissions of greenhouse gases.
    Over this 100-year period, O’Gorman found that average snowfall decreased substantially in many Northern Hemisphere regions in warm-climate scenarios compared with the milder control climates, but that snowfall amounts in the largest snowstorms did not decrease to the same extent.
    He warned, however, that changes in snowfall extremes can be larger in regions with little snowfall to begin with, such as the southwestern United States. He also notes that while this study focuses on percentage changes in the amount of snowfall in extreme snowfall events, there can be larger changes in the frequency of such events.
    From the simulations, O’Gorman found that it takes greater climate warming to reduce the intensity of extreme snowstorms than to reduce average seasonal snowfall. Specifically, a region would experience less seasonal snow if average winter temperatures were initially above minus 14 degrees Celsius (7 degrees Fahrenheit). But the heaviest snowstorms would become less intense only above minus 9˚C (16˚F).
    A sweet spot for extreme snowfall
    What’s more, O’Gorman found that there’s a narrow daily temperature range, just below the freezing point, in which extreme snow events tend to occur — a sweet spot that does not change with global warming. This is in contrast to average snow events, which may occur over a broader temperature range.
    “People may know the expression, ‘It’s too cold to snow’ — if it’s very cold, there is too little water vapor in the air to support a very heavy snowfall, and if it’s too warm, most of the precipitation will fall as rain,” O’Gorman says. “Snowfall extremes still occur in the same narrow temperature range with climate change, and so they respond differently to climate change compared to rainfall extremes or average snowfall.”

  55. Genghis says:

    Izen, – “An alternative view might be that the Muslim civilisation, a literate and scientifically developed culture was lucky in having the civic organisation and military skills to defeat a marauding migration of illiterate nomadic pastoralists. And stopping the Mongols. Who decimated Russia and China instead.

    Use a search engine to look up the career of Baibars, 13th-century Mamluk Sultan of Egypt.

    You need to check your dates, Genghis was probably dead before Mamluk was born. And while you are correct that he did defeat some remnants of the Mongol forces, they had already conquered most of the ME, not to mention Russia and most of China.

    It was also Genghis Khan who defeated the Assassins, not Mamluk.

  56. Here is the warm water coming up from the Bermuda Triangle

    Oh, I have always been afraid that the truth will come out eventually. We have been working so hard to prevent that. An elaborate hoax was created, entire physical theories created, billions put in the “models”. Everything for the cover up. All of it for nothing now.

  57. Tom Curtis says:

    Joshua:

    “Depending on your measurement methodology, it would seem to me that saying that storms will be more intense is kind of the same thing as saying that the number of extreme storms will increase”

    If I remember correctly, IPCC predictions for Queensland is that category 5 cyclones will become more frequent as a proportion of all cyclones; but that the number of cyclones will decrease. Further, if I have done my maths right, the number of category 5 cyclones will also decrease overall. Treat the situation as hypothetical. It is, however, a situation that could arise and is one in which the storms become more intense, but that the number of extreme storms will decrease.

    (I am posting this in haste due to a timeline and have not read all of your post or subsequent discussion. Sorry if I am just repeating something covered in subsequent discussion.)

  58. Clausius-Clapeyron formula tells, how moisture increases with temperature, but evaporation is constrained by energy flux, not temperature. The sum of latent heat transfer, sensible heat transfer, and net IR is essentially constant. The relative shares change, but latent heat transfer is so dominant that it cannot increase much.

  59. izen says:

    @-Jan P Perlwitz
    “Bermuda Triangle … An elaborate hoax was created, entire physical theories created, billions put in the “models”. Everything for the cover up. All of it for nothing now.”

    Relax, despite the ‘coincidence’ of submarines at the North Pole just after the International Geophysical Year, the start of the Keeling curve and decades of nuclear subs from both ‘sides’ supposedly ‘watching’ each other, they still think AGW is why the Arctic ice keeps shrinking!

    http://www.navalhistory.org/2011/08/11/uss-skate-ssn-578-becomes-the-first-submarine-to-surface-at-the-north-pole

    (grin)

  60. Steve Bloom says:

    Increased moisture available for snow combined with a shorter season in which it’s cold enough to snow (IOW the reduced number of potential snow days is not evenly distributed) is the way to describe this. The first factor got a lot of discussion in the OP and comments, but the second factor, although it could have been inferred, in particular from the O’Gorman paper, never got a direct mention. IMO it’s absolutely key for public understanding of what’s going on.

  61. MikeH says:

    @Vinny

    As I understand it, Pielke’s post was a response to Michael Mann, who had been citing (apparently out-of-date) peer-reviewed literature to support his view that the coming winter storm would be driven by climate change.

    It is not nice to verbal someone. I have not checked all his comments but I do follow his twitter feed. My guess is that you made up “would be driven by climate change” as my reading of Mann’s comments is that he was saying “would be enhanced by climate change”.

    He was pointing to the IPCC report listing more intense extra-tropical storms as “likely” as Pielke Jr uses the report as a stick to beat his critics with with if they suggest anything that is not rated “likely” or more in the report.

    And he cited this paper from January 2015 (so not out of date)

    Previous studies investigating the impacts of climate change on extratropical cyclones have primarily focused on changes in the frequency, intensity, and distribution of these events. Fewer studies have directly investigated changes in the storm-scale dynamics of individual cyclones. Precipitation associated with these events is projected to increase with warming owing to increased atmospheric water vapor content.

    Precipitation increases at a rate slightly less than that dictated by the Clausius–Clapeyron relation with warming.
    http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00418.1

  62. With all extreme events we must remember what extreme means: rare and highly variable in details of extremity.

    GMST warming by, say, 1 C is likely to lead to modest changes in the distribution of extreme events. Highs go typically also up by 1 C, but in some regions the changes may be larger. One example comes from the other edge: We have Arctic amplification and I think that that’s to a significant degree due to reduction in extreme colds. There may be hot dry regions, where we have amplification of hot extremes, but I don’t know whether that is the case (perhaps in parts of Australia, someone might know).

    Similarly warmer oceans lead to higher humidity and some increase also in evaporation and precipitation, but these changes are not very large on the average. If an extreme case of rain or snowstorm produces a few percent more precipitation, that’s not really significant on the level we observe extreme events (e.g., a snowstorm of 53 cm rather than 50 cm, who would notice). It’s possible that some changes are more significant, but in discussing that we move into speculation. Climate models are not good enough for telling much more.

  63. Pekka,

    If an extreme case of rain or snowstorm produces a few percent more precipitation, that’s not really significant on the level we observe extreme events (e.g., a snowstorm of 53 cm rather than 50 cm, who would notice).

    Sure, but the frequency is also important. If an extreme snowfall event is defined as more than 20inches and it would normally happen once every 20 years, but now happens once every 5, that would – I think – be noticed.

  64. aTTP,
    My point is that when the distribution shifts a slightly higher rainfall is then as likely than the slightly lesser was before.

    Those claims about very large relative changes in some kind of extreme events are based on misleading use of PDFs of Gaussian type that have a very sharp cutoff for the tails.

  65. Pekka,

    Those claims about very large relative changes in some kind of extreme events are based on misleading use of PDFs of Gaussian type that have a very sharp cutoff for the tails.

    Okay, yes I agree, some of the claims made about changes in distributions have been wrong.

  66. aTTP,
    Attempts to justify quantitatively questionable claims have not been very common, but claims that are presented without even an attempt to consider the properties of relevant PDFs are ubiquitous.

    Anyway. If the effect is small when looked at in the way I prefer, then it is small, whatever the relative change in a small probability is.

  67. Andrew Dodds says:

    @Steve Bloom

    A reduced number of snow days makes the problem worse to some degree.

    The problem the UK had in the two recent cold winters was that we’d had a run of extremely mild winters, so many of the resources for dealing with snow had been run down. And of course, here in the South West the council has spent money on preparedness and we’ve had no noticeable snow this year or last.

    So a pattern of snowfall being rarer, but more intense when it happens, is the worst possible outcome as far as being prepared goes.

  68. Dan Hughes says:

    Pekka has it right.

    As application of the interfacial jump condition ( Slattery Advanced Transport Phenomena, Slattery Interfacial Transport Phenomena ) for the total energy conservation equation clearly indicates.

    The net of the thermal energy gradients into the interface from each side of the interface determines the response of the mass and energy exchanges.

    The gradients of the driving potentials in each of the materials that form the interface, and not the level of the potential on only one side of the interface, are the significant and correct approach.

    Steven Mosher how were the metrics normalized for the fact that each of the members of the ensemble will have different conditions in temperature level ( the Clausius-Clapeyron approach ) and driving potential gradients at the interface ( the correct approach ).

  69. Eli Rabett says:

    Variability is the key here again, within the range of the possible, is the coincidence of a cold storm coming across from the mid west coinciding with very warm water off the East Coast and a circulation pattern moving water vapor evaporated from the surface into the mid-Atlantic States and especially New England.

    This one had it all. Extremely hot sea surface temperatures off the coast, a wind pattern moving the water vapor evaporated from the surface into NE and Long Island and the cold front hitting the mass of water. While strictly speaking the Clausius Clapyron (CC) relationship only applies to an equilibrium, it gives you a good idea about the relative rates of evaporation as temperature changes (points to ATTP). The wind blowing along the top give you a good picture of how the non-equilibrium situation contributes to a sharp increase in the amount of water vapor available (points to Pekka), and at the cold front, the CC again tells you how the water vapor is removed as snow.

    Northeasters are not only snow bombs, but also include rain and wind during the summer. Go watch “A Perfect Storm”

    Which raises the important point that damage from climate change will primarily be due to strong local variation of some weather parameter on top of an increasing trend driven by global climate change,

  70. Dan,

    Pekka has it right.

    Yes, and I think that is what is discussed in some detail here (H/T Frank). That doesn’t change that warming will lead to more water vapour in the atmosphere, an increased evaporation rate and – consequently – an increased precipitation rate.

  71. Eli Rabett says:

    Roger claims to be focusing on science but is really seeking to advance his policy agenda. When such claims are made, the authority of science is used to hide a policy agenda, under an assumption that science commands that which policy does not. However, when stealth issue advocacy takes place, it threatens the legitimacy of scientific advice, as people come to see it simply as policy advocacy, and lose sight of the value that science does offer policy making .

    Roger really needs to be called out as the stealth issue advocate he always has been hiding under the honest broker meme he seeks to project.

  72. John Hartz says:

    Eli: Kudos for your comprehensive and digestable explanation of the mechanisms causing a Nor’easter storm and how manamde climate change impacts those mechanisms.

    Other commenters seem to be focused on statistical analyses of this or that component of the weather/climate system.

  73. Eli,

    Roger really needs to be called out as the stealth issue advocate he always has been hiding under the honest broker meme he seeks to project.

    Roger’s schitck is all rather ironic. Promoting the Hartwell/BTI ideas of removing science from the table while pushing very specific bits of “science” whenever challenged or whenever he decides to challenge someone else.

  74. John Hartz says:

    Eli: Kudos on your insightful explantion of the propaganda game being played by Roger Pielke Jr.

  75. Albatross says:

    This episode demonstrates that Roger is, amongst other things, a pundit.

  76. John Hartz says:

    ATTP: Fodder for a future post…

    Claims that climate models overestimate warming are “unfounded”, study shows by Roz Pidcock, The Carbon Brief, Jan 28, 2015

  77. JH,
    Yes, I downloaded the paper today. Was planning to write a post. Something technical might be a nice change 🙂

  78. matt says:

    OT. Rachel are you aware of previous winners of this award? ATTP should do what Sks did and not participate. This award, is a joke.
    ***********************************************
    WEBLOG OF THE YEAR (2013, 2014)

    Watts Up With That?

    ***********************************************
    BEST SCIENCE OR TECHNOLOGY WEBLOG (2013):

    Winner:
    WUWT

    FInalists:
    Jo Nova
    Tallbloke’s Talkshop
    Skeptical Science withdrawn by request
    Climate Audit
    ************************************************
    BEST WEBLOG ABOUT POLITICS (2013):

    Winner:
    James Delingpole

    *************************************************
    LIFETIME ACHIEVEMENT (2014)

    Winner:
    JoNova
    *************************************************
    If ATTP hopes to ever get a lifetime achievement award from this organisation, he will have to compete with this.

    Jo Nova:

    “[The] most important articles I’ve ever published” are http://scienceblogs.com/stoat/2014/06/18/force-x-from-outer-space/ (the same year she receives the lifetime achievement award)

    “Behind the scenes a major advance has been quietly churning… He’s discovered something extraordinary… it all seemed so obvious in hindsight we wondered why no one had done this before…

    [He] developed something the climate debate has needed, but failed to do achieve after 30 years, despite billions of dollars in funding… Make no mistake, this is not like anything I have seen or read about. It fits, like all good science does, into a coherent theory that matches the data and connects many other papers…

    I will boldly predict that many papers will spring from this work and its implications, but for the moment we see no reason to wait for two unpaid reviewers and an editor (with little knowledge of the details) to delay or prevaricate on its release.

    Historically this is how real science is done, one well-trained passionate researcher pursues a creative idea that breaks the current paradigm, then sets the theory free for everyone to test and review…

    [These are the] most important articles I’ve ever published.”

    [Ah, yes. Force X from outer space. I probably should have mentioned that, since I spent a fair time commenting there. For something so desperately important, its all gone as quiet as AW’s paper, no? -W]

  79. Albatross says:

    It is foolish of Roger to try and rail against the Clausius–Clapeyron relation. In short, east coast storms are expected to intensify (as quantified by their central pressure) with an attendant increase in the surface winds and precipitation intensity.

    1) From Marciano et al. (2015) [“Changes in U.S. East Coast Cyclone Dynamics with Climate Change”]:

    “Present-to-future changes in the storm-scale dynamics are assessed using Earth-relative and storm-relative compositing. Precipitation increases at a rate slightly less than that dictated by the Clausius–Clapeyron relation with warming. Increases in cyclone intensity are seen in the form of minimum sea level pressure decreases and a strengthened 10-m wind field. Amplification of the low-level jet occurs because of the enhancement of latent heating.”

    http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00418.1

    2) From Lombardo et al. (2015) [“Evaluation of Historical and Future Cool Season Precipitation over the Eastern United States and Western Atlantic Storm Track Using CMIP5 Models”]

    “Subsequently, the projected changes in precipitation on cyclone and noncyclone days under the representative concentration pathway 8.5 (RCP8.5) scenario were quantified. While precipitation on both types of days was projected to increase, the increase on noncyclone days (23%) was greater than the increase on cyclone days (12%). The increase in precipitation on cyclone days occurred despite a decrease in the number of cyclone days. This increase can be attributed primarily to a shift toward more frequent extreme precipitation events coupled with a decline in light precipitation events.”
    http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00343.1

    3) From Colle et al. (2013)[“Historical Evaluation and Future Prediction of Eastern North American and Western Atlantic Extratropical Cyclones in the CMIP5 Models during the Cool Season”]

    “The best seven models were used to determine projected future changes in cyclones, which included a 10%–30% decrease in cyclone track density and weakening of cyclones over the western Atlantic storm track, while in contrast there is a 10%–20% increase in cyclone track density over the eastern United States, including 10%–40% more intense (<980 hPa) cyclones and 20%–40% more rapid deepening rates just inland of the U.S. East Coast."

    http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00498.1

  80. matt,
    Yes, I agree, it is a rather a joke and I no great desire to be able to claim an association with an organisation that manages to award Best Science of Technology Blog to WUWT.

    Albatross,
    Thanks.

  81. John Hartz says:

    ATTP: Even when you author a rather innocuous OP such as this one, you open a proverbial “can of worms.” (:

    Here’s another important consideration…

    SNOWFALL MEASUREMENT: A FLAKY HISTORY

    The teaser: Many pre-1990 numbers would be higher using current methods

  82. Rachel M says:

    Matt,
    Yes, I know about the problems with the bloggies. But they’ve done away with the Science category now and WUWT is no longer eligible to be nominated for the best topical weblog category.

  83. Willard says:

    > Roger really needs to be called out as the stealth issue advocate he always has been hid.

    I disagree, at least a bit. Junior has made clear he was an advocate, or at least he never claims being an honest broker. That’s a role for institutions.

    However, it does seem that he plays the honest broker from time to time, say in the hurricane wars. It also seems that he’s misplaying the fact/value dichotomy with the very idea of honestly brokering. His appeals to pragmatism are far from optimal. His hiding under every line he wrote is a bit silly too:

    Albatross could fill up a book of all the times Junior tapdanced in front of him. Junior’s not the best dodger in the history of Climateball for no reason.

  84. Joshua says:

    Albatros –

    ==> “It is foolish of Roger to try and rail against the Clausius–Clapeyron relation.”

    Could you be more specific? I mean yes, Roger does like to hide behind plausible deniability to make implications, deny that he’s made them, and then say “Thanks!” — but I question whether even if we strip away that tactic, we’d see what you describe.

  85. Joshua says:

    ok – I’ve been wondering about whether I should post the following… but in the end I’ve decided, well what the hey.

    Tom Curtis –

    ==> “If I remember correctly, IPCC predictions for Queensland is that category 5 cyclones will become more frequent as a proportion of all cyclones; but that the number of cyclones will decrease. Further, if I have done my maths right, the number of category 5 cyclones will also decrease overall.”

    Hmmm. I don’t get then, how that would fit with AGW —> more extreme weather…except then you say…

    ==> “Treat the situation as hypothetical. It is, however, a situation that could arise and is one in which the storms become more intense, but that the number of extreme storms will decrease.”

    So let me risk embarrassment once again by trying to summarize my understanding (if what follows is so confused and over-simplified that you can’t even figure out where to begin in clarifying my understanding – no problem. I’m mostly just trying to figure out what I think).

    There could be two (basic) ways that “extreme events” might increase. One way (for which there doesn’t seem to be solid evidence from observations as of yet) would be that “extremeness” increases across the board – pushing what might have been non-extreme events, absent increased warming, above the threshold. This, AGW would = more extreme weather events.

    The other (for which there seems to be some solid evidence from observations) might be that the factors which cause extreme events could be altered such that extreme events become more intense. For example, certain dynamics that might have lead to 2′ of snow would now lead to 2’+ amounts of snow due to greater warmth (and as a result moisture) in the atmosphere. In other words, the dynamics that produce large snowstorms could be exacerbated. But that outcome could occur even as the frequency of those dynamics manifesting might remain constant or even decrease .

    But it wouldn’t make good sense to limit the scope of the discussion to snow events because of factors like that increasing temperatures that could make reaching the snow sweetspot a less frequent event – and thus a more meaningful metric is precipitation of all sorts.

    Likewise, it wouldn’t be sufficient to try to measure the relationship between AGW and changes in “extreme weather” merely by counting the frequency of extreme events focused on some binary inclusion/exclusion criterion over time. IOW, it makes sense to evaluate changes in “intensity” as well. Fewer (or the same amount of) “extreme” storms of greater intensity, relatively could have a more negative impact on society.

    And any of these dynamics might be localized phenomena, so trying to make links to a more generalizable impact of AGW would have to be done carefully.

    And while observations of recent trends in extreme weather might help inform our evaluation of modeled impact of AGW on extreme weather, great care should be taken in examining that relationship – as we can’t logically assume that a lack of signal in recent years means that the projections of the modeling is incorrect – and we certainly wouldn’t anyone to be mistaken about that 🙂

    —————-

    Questions: I thought that I read somewhere that depending on temperature, a given amount of moisture in the atmosphere might produce varying amounts of snow. Is that right?

    Also, what is the state of the evidence regarding trends in precipitation, globally? Is there the sense that it would be balanced out globally to some degree from increased intensity of precipitation in some regions while increased drought in others – but even still, wouldn’t the physics of AGW suggest that there should be an overall trend of increase in global precipitation (warmer temps, more moisture in the atmosphere – that has to do somewhere)?

  86. Pekka, it is somewhat optimistic to assume that the extremes will change like the mean. Also the variability around the mean is expected to change. (Sometimes gets smaller, sometimes gets larger.) For changes in extremes, especially for the most extreme extremes, any changes in the variability are expected to be most important.

  87. Joshua,
    I think the point is that Tropical Cyclones are very complex and are influenced by a number of factors. One being, I think, the latitudonal temperature gradient. Hence, it’s possible – I think – that AGW could change the latitudonal temperature gradient in such a way that TCs become less likely, but when they do happen they are more likely to be strong.

    Maybe this is an opportune time to promote this old post of mine about Roger Pielke Jr’s work on the The emergence timescale for trend in US tropical cyclone loss data. The basic message from the paper was that it could take more than 200 years for a statistically significant trend to emerge. A couple of issues though (and that I thought weren’t promoted well in the paper). This was the time when 95% of his 10000 monte carlo sims had emergent trends. The 5-95% range was something like 30 – 230 years from now. Also, the models suggested a significant increase in the number of category 4 and 5 TCs and so one reason the losses didn’t change much was that the increase in the losses due to extreme TCs was balance by a decrease in losses due to the more common less-extreme TCs. Personally, a world in which all the losses come from category 4 and 5 TCs seems like quite a different one in which the losses are the same, but it’s mostly due to category 3 TCs.

  88. Michael 2 says:

    ATTP Says: “Additionally, in a warmer world, we expect the evaporation rate to increase. If the rate at which we add water vapour to the atmosphere increases, then the rate at which it falls out of the atmosphere has to also increase.”

    Of course you expect it. I don’t. A step increase in air temperature increases its vapor holding capacity. All other things being equal, evaporation will increase briefly until the air reaches its new equilibrium, which I suspect takes only minutes or hours at most. Then the rate of evaporation returns to zero for that particular volume of air.

    What is required for a hydrologic cycle is some place cold that can force condensation. As global warming is theorized to reduce the temperature gradient between equator and pole, less cold exists; much less cold than an increase in warmth; the net effect of which is to reduce overall precipitation even though warmer air will indeed be holding more water molecules. They’ll just stay there. Hot and humid and unstable. Lots and lots of latent heat.

    A few places on earth will rain more; the Himalayas for instance which are so high they extract nearly all water vapor anyway.

    The echo (Johnrussel40) says “If the atmosphere is warmer, physics says it sucks up more water from wherever it can get it.”

    Yes, until it reaches its new saturation, then it stops.

    “Physics also says that what goes up, must come down.”

    Book, chapter and verse, please. Tell it to Voyager. Here’s to hoping that the Sears Tower doesn’t come down any time soon!

    “Therefore it follows that precipitation has to increase”

    In your imagination obviously.

    “Or is this too simplistic?”

    Yeah, something like that. About what I’d expect from an echo. So, what is going to make water vapor “come down”?

  89. Albatross says:

    Hiya Joshua,

    Sorry, only getting online now, it has been a busy day.

    Think of it this way, Roger is suggesting that there has not been an increase in heavy precipitation events or strong nor’easters along the eastern seaboard of the U.S. during the boreal cool season. For that to be true, would require ignoring the physics and dynamics driving these storms. And specifically referring to intense precipitation, his claims would require that the storms defy the CC relation, because the increase in precipitation amounts scales with the amount of warming as per the CC relation.

    Now he may not be saying so explicitly (he hasn’t the guts to do that, because it will expose his end game), but my above explanation is the logical and physical implication of his arguments. Sorry if I did not explain this very well, like I said, long day and I’m tired.

    Roger Pielke Jnr. is quite simply an egocentric pundit who craves attention and is the very antithesis of an “honest broker”.

  90. M2,

    All other things being equal, evaporation will increase briefly until the air reaches its new equilibrium, which I suspect takes only minutes or hours at most. Then the rate of evaporation returns to zero for that particular volume of air.

    No, if the relative humidity stays the same, and the temperature increases, then the evaporation rate goes up. Of course, in a quasi-steady state, this is matched by an equal precipitation rate, so that the amount of water vapour in the air is unchanged.

  91. M2,
    Evaporation is expected to increase both directly as consequence of increased CO2 and as consequence of higher temperatures.

    Increased CO2 reduces net IR energy transfer out of oceans by making the atmosphere more opaque. The change is not very large, but it’s not negligible.

    Increased temperature increases absolute humidity. That makes also the atmosphere more opaque, but again the change in net IR is not large, but not negligible. Increased humidity means also that the same net flow of air moves more latent heat, and that moving a fixed amount of energy requires less mass flow.

    To get the whole energy flux into balance with heating of the oceans by solar SW, a less net IR means that slightly more heat has to be transferred by convection. The mass flow of convection does not grow that much and may go even down as the convection moves more latent heat per unit of mass. Less mass flow leads to less sensible heat transfer.

    To conclude, the shares of both net IR and sensible heat transfer go down, and the share of latent heat transfer goes up, meaning that also evaporation increases, but it increases less than absolute humidity, because it’s share is large already before the changes.

    Some important weather phenomena like tropical cyclones get their violent energy from condensation of moisture. Thus it’s surely natural to expect that they get stronger with more moisture. Their whole existence requires warm ocean water. That something is a natural expectation should, however, always be taken with grain of salt, because the phenomena are complex, and something else may cancel the expected behavior.

  92. John Hartz says:

    Here’s another candidate topic for a future post:

    World’s cities experiencing more heatwaves, study shows by John Vidal, The Guardian, Jan 29, 2015

  93. Hyperactive Hydrologist says:

    I have linked two interesting papers below. The first uses very high resolution weather models (1.5km grid) which is able to accurately model convection to model future rainfall in southern UK. The results show an increase in extreme rainfall events consistent with what would be expected based on the Clausius–Clapeyron relation. In addition they show a 5 times increase in extreme events with rainfall above 30mm/hour.

    http://www.nature.com/nclimate/journal/v4/n7/full/nclimate2258.html

    The second is a review paper on extreme rainfall on the sub-daily timescales, interestingly:

    Thus, rather than exhibit a consistent scaling rate of approximately 7% per °C as expected from the discussion in section 2.1, observational studies have shown rates of up to double the CC rate for temperatures between ~12°C and ~22°C and negative scaling rates for higher temperatures.

    http://onlinelibrary.wiley.com/doi/10.1002/2014RG000464/abstract

  94. Eli Rabett says:

    Roger is a STEALTH issue advocate, the foulest of beasts in his closet.

    Thanks John, Eli appreciated that

  95. Frank says:

    ATTP: In response to your above question, I spent several hours reading the literature on extreme precipitation. Nothing I found told me with any statistical confidence how extreme events like the Blizzard of 2015 have changed since GHG-mediated global warming began around 1975. (Before 1950, warming was mostly caused by natural variability, not GHGs. Here in the US it was accompanied by the Dust Bowl era drought. Between 1950 and 1975, rising aerosols – which can directly effect clouds and precipitation – suppressed warming.) In particular, I tried to learn one of two things for the US:

    1) How much has the return time for an extreme precipitation event of a certain size shrunk since 1975 (and is this shrinkage is statistically significant)? Is an event that occurred once a decade before 1975 now occurring every nine years or every five years? (One paper reported a 20% shrinkage in some regions but not others and the change was around the “likely” threshold.)

    2) How much more rain or snow (as a percentage, not an amount) falls today in a once-a-decade (or any other return period) extreme precipitation event?

    I didn’t find any useful and convincing answers to these practical questions that put the increase in extreme precipitation into a context that the average citizen can understand. I would be very interested in reading any posts that attempt to do so.

    As for the future, the grid cells in climate models are far too big to properly represent the localized convective events that cause extreme precipitation. I don’t know why anyone would place any faith in their quantitative projections. However, the idea that a warming world will increase rainfall where it is plentiful and decrease rainfall where it is scarce is allegedly based on simpler physics. I’ve never found a physical explanation for this prediction, and would very much like to read one. Warmer air can carry more water vapor, but the amount of rain that falls depends on the temperature difference between the top and bottom of the convective region. The lapse rate is expected to decrease in the future, not increase. So is the temperature difference between the poles and the equator, which creates the colliding warm and cold fronts that cause extreme precipitation. It seems to me that increased extreme precipitation requires taller convective towers, not just warmer, moister air. We do find the tallest convective towers in the tropics, so perhaps the rise extreme precipitation can best be understood in terms of latitude. Is the increased extreme precipitation we will experience after 2-4 degC of warming similar to that experienced by moving south a 200-400 m miles south (which also causes a 2-4 degC rising in mean annual temperature on the average)? Is this moving south 200-400 miles something the average citizen should be fear?

    Sorry to sound so skeptical, but there seems to be a great deal of politically-motivated hype surrounding extreme weather. I am sincerely interested in the science behind extreme weather.

  96. dhogaza says:

    M2:

    “What is required for a hydrologic cycle is some place cold that can force condensation. As global warming is theorized to reduce the temperature gradient between equator and pole, less cold exists; much less cold than an increase in warmth; the net effect of which is to reduce overall precipitation even though warmer air will indeed be holding more water molecules. They’ll just stay there. Hot and humid and unstable. Lots and lots of latent heat.”

    Which is why it is so dry in the tropical rainforest …

    Have you ever heard of convection … storm cells … or noticed that Arizona’s “monsoon” season is late July-August when it is hottest and when (in normal years) warm, humid air from the Gulf flows over the state?

  97. Frank,

    Nothing I found told me with any statistical confidence how extreme events like the Blizzard of 2015 have changed since GHG-mediated global warming began around 1975.

    Well, this might explain your problem. It’s not so much that the event itself is different, it’s that such events become more common.

    Before 1950, warming was mostly caused by natural variability, not GHGs.

    This isn’t quite correct. The time since 1950 is the period during which we’re confident that most of the warming was anthropogenic. It also depends on what you mean by natural variability. In the period 1900 – 1950, it was probably a combination of an increase in solar insolation and anthropogenic forcings.

    Sorry to sound so skeptical, but there seems to be a great deal of politically-motivated hype surrounding extreme weather. I am sincerely interested in the science behind extreme weather.

    If you are, then I think the basics are quite simple. There is evidence that we’ve seen an increase in the frequency and intensity of extreme precipitation events (see some of links in other comments, for example). Other extreme events are trickier. Tropical cyclones may, for example, reduce overall but we would expect (given higher sea surface temperatures) that a larger fraction of those that occur will extreme.

    Another issue to bear in mind is that sea level is also rising. This means that a landfalling TC could do more damage than before, even if the TC itself it not especially extreme.

    If you think there’s politicization associated with those who link extreme weather and AGW, what about those who almost instantly shout down anyone who does so?

  98. aTTP,

    As Karsten commented at the very top of comments, there isn’t clear direct evidence that the extreme events have become more common. The nature of the statistics is such that drawing strong conclusions requires much more data than there is. (Or much better understanding of weather phenomena.)

    If we consider the resent years, certain uncommon patterns have dominated the state of the Pacific. Thus there may be one single reason that has affected whether over wide areas over several years (having perhaps the “hiatus” as one consequence). If one single reason is important, and it’s causal origin unknown, then the statistical significance of many observations is really weak.

    Some models predict sizable changes, but the models are not known to be reliable on this kind of detail.

  99. Pekka,

    As Karsten commented at the very top of comments, there isn’t clear direct evidence that the extreme events have become more common.

    I’m not sure that I said “extreme events have become more common”. I said “precipitation events” specifically because – as I understand it – there is evidence for an increase in extreme precipitation events. I agree that the evidence for an increase in other extreme events is not as clear.

    Some models predict sizable changes, but the models are not known to be reliable on this kind of detail.

    Yes, I realise.

  100. aTTP,
    Even on precipitation events, the evidence is probably weak. When people study such events, they typically consider many alternative approaches for the methods and the data set and select the one that they judge as most likely to give a clear signal, but such a selection biases the outcome, and makes evaluating the significance of the results very difficult or even impossible.

  101. Pekka,
    Hmmm, well that’s not what I’ve taken from what I’ve found recently, unless you’re suggesting that maybe they’re wrong.

  102. Michael 2 says:

    ATTP restates:

    “if the relative humidity stays the same, and the temperature increases, then the evaporation rate goes up.”

    That puts the cart before the horse, declaring as an independent variable the thing that is dependent.

    So let’s manipulate the independent variable, heat which eventually results in increased air temperature.

    As air increases in temperature, it’s relative humidity goes down.

    As relative humidity goes down, the capacity for air to hold more vapor increases.

    Whether it actually gets more water vapor depends upon a suitable source of water AND energy to vaporize it — rather a lot of energy, way more to vaporize 1 gram of water than it takes to raise 1 gram of water 1 degree. That energy lives in the vapor as latent heat and doesn’t, by itself, increase temperature.

    Thick: http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/State_Functions/Enthalpy/Enthalpy_Of_Vaporization

    Thin: http://en.wikipedia.org/wiki/Enthalpy_of_vaporization

    The point of that is that the rate of evaporation isn’t connected to relative humidity but to the heat energy being applied to water raising the temperature of water but mostly kicking molecules of water off the surface into the air.

    Steam engines work into 100 percent RH; there’s nothing but water vapor in those pipes, and yet you still have “evaporation” pushed along by burning coal, oil or solar energy.

    So the rate of evaporation has nothing to do with RH and everything to do with heat.

    I think that is what Pekka was sort of trying to write.

    The opposite, condensation, requires the removal of heat, and that requires a heat sink.

    As global warming eliminates heat sinks, it also eliminates condensation.

    The rate of precipitation is independent of the rate of evaporation. To be sure, you cannot precipitate more vapor than has been put into the system. But can you precipitate less? Yes or no, depending on what you mean by “precipitation”. If you mean RAIN, then yes, there is no automatic connection between evaporation and rain because rain is only one of several possible outcomes of increased evaporation.

    Suppose global warming eliminated heat sinks entirely, no cold spot on earth to trigger precipitation at that place. Eventually the atmosphere would become 100 percent relative humidity everywhere, saturated!

    Would evaporation cease? No. Evaporation doesn’t care about R.H., only heat! So what would happen is that water continues to evaporate, finds itself immediately supersaturated and precipitates right then and there at the point of evaporation; all bodies of water would have a thin fog over them of instantaneous precipitation — but NOT increasing rainfall in Nairobi.

    So, pedantically speaking an increase in evaporation will indeed eventually produce more precipitation, but not necesssarily as weather. It could just be fog hovering over the point of evaporation as precipitation immediately follows evaporation.

    I lived in Hawaii for a number of years. I was surprised that it’s relative humidity was not 100 percent round the clock. How is that possible?

    http://w1.weather.gov/obhistory/PHNL.html

    Notice that the nighttime humidity goes up to nearly 100 percent, typically 50 percent in the day. What happens is at night the air is “wrung out” with plenty of precipitation, mostly over the ocean. The sun rises, heats the air — but evaporation is constrained by sea surface temperature! It is rate limited by water temperature, not air temperature.

    I should point out that in the case of immediate precipitation as steam or fog, the heat that caused the vaporization is still in the air — released from water vapor and is now “dry heat” and rather a lot of it. This heats the air, which of course has a side effect of increasing its vapor holding capacity. It also rises!

    The resulting “plume” of warm, moist air rises fast and high, at the edges of the plume the cooler air forces precipitation which releases even more heat into the plume. It spins, and viola, you have a tornado and/or a spectacular thunderhead 10 thousand meters high releasing megajoules of heat into space and quite a lot of rain, hail or snow back to Earth.

    A warmer atmosphere is not assuredly going to produce this phenomenon. The heat has to be applied to WATER combined with a warmer atmosphere. You need lots of latent heat, that’s the fuel for our engine, and you need a temperature differential which is true for both Stirling cycle and Carnot cycle engines. Global warming reduces temperature differentials on a global scale but you’ll still have regional and local cold spots to initiate the thermal engine.

  103. aTTP,
    I do, indeed, think that some recent papers on increased precipitation events are based on suspect statistical analysis that does not take all those factors into account that may lead to spurious results. My above comments list some of the reasons that make me think so.

  104. Pekka,
    Okay, fine, but there appear to be plenty of sources that suggest a statistically significant increase in extreme precipitation events. Plus, there’s the C-C relation etc….

    M2,
    Given that 70% of the planet is ocean and an increase in temperature, without an increase in RH, would lead to enhanced avaporation, it’s hard to see how we can avoid specific humidity increasing. At the moment, it appears that we would expect RH to remain roughly constant. As I understand it, the only way we can avoid increased evaporation is for RH to go up.

  105. M2,
    I don’t agree on what you write, but I’m not going to write more on that tonight (it’s midnight here).

  106. I don’t agree on what you write, but I’m not going to write more on that tonight (it’s midnight here).

    I don’t blame you 🙂

  107. BBD says:

    Pekka

    If we consider the resent years, certain uncommon patterns have dominated the state of the Pacific.

    Can we say that this is not a consequence of the increase in OHC and tropospheric temperatures over the last several decades, predominantly a result of anthropogenic forcing?

    If one single reason is important, and it’s causal origin unknown, then the statistical significance of many observations is really weak.

    Is it really ‘unknown’?

  108. Michael 2 says:

    ATTP says “it’s hard to see how we can avoid specific humidity increasing. At the moment, it appears that we would expect RH to remain roughly constant. As I understand it, the only way we can avoid increased evaporation is for RH to go up.”

    I concur that it is nearly certain that the total amount of water vapor in the atmosphere will increase with global warming. It is nearly certain because the extreme opposite scenario, “snowball Earth”, has essentially no vapor in the atmosphere.

    I do not concur with some assumptions that derive from it. The change in total vapor load will be a step increase following a step increase in atmosphere temperature. The rate at which is takes place is governed by water temperature, not air temperature (mostly). At any rate, a new equilibrium will be reached, probably (as you suggest) at the same RH.

    What is considerably less certain is that more rain will result from this. Precipitation will increase, but most of that will take place at the point of origin, same as precipitation from a hot kettle of water. What manages to stay in vapor form will be substantial, but what can remove it?

    Two natural scrubbers exist — the Hadley cell for the tropics (don’t need no steenkin mountains to make it rain in the Amazon or Congo), and mountains elsewhere.

    The third trigger is atmospheric temperature differential, largely caused by the difference in temperature at the poles and equator; also the daily temperature change which can produce some interesting atmospherics (cloud rolls in Australia).

    That third trigger is reduced by unequal warming of the earth reducing differential.

    Regions that depend on atmospheric self-scrubbing will probably (in my non-expert opinion) have less rain, that will include the central United States and rather a lot of Russia. Mountain ranges will probably get more BUT if the condensation elevation rises, more vapor will get over the mountains. Whether any of that succeeds in raining out in the rain shadow remains to be seen but is unlikely.

    I remember reading a science fiction story many, many years ago about a science experiment to create rain. A laser was shone straight up. It took days for it to have any effect, but by gently heating a small column of air, it started a low pressure cell which created a cyclonic inflow and rising column of air which “started the engine” so to speak. It would work if the conditions are such that RH is near 100 percent but there’s no natural triggers to start the thermal engine.

  109. John Hartz says:

    The following paper may contain information that bears directly bears on the ogoing discussion about the relationship between precepitation and climate change. Also note the extensive listing of related papers cited.

    A framework for assessing hydrological regime sensitivity to climate change in a convective rainfall environment: a case study of two medium-sized eastern Mediterranean catchments, Israel, N. Peleg. F. Shamir, K. P. Georgakakos and E. Morin, Hydrol. Earth Syst. Sci., 19, 567–581, 2015

  110. MikeH says:

    An fairly comprehensive explainer from Kevin Trenberth.
    https://theconversation.com/does-global-warming-mean-more-or-less-snow-36936

    with a couple of relevant references at the bottom of the article.

  111. Eli Rabett says:

    First,the CC relationship holds in the marine boundary layer. In that small layer of the atmosphere increasing SST increases absolute humidity, and Eli appears to remember that RH=100% there.

    Circulation moves the water vapor from the MBL to the rest of the atmosphere, resulting in non-100% RH, but as a general rule close to the MBL RH is higher.


  112. there isn’t clear direct evidence that the extreme events have become more common. The nature of the statistics is such that drawing strong conclusions requires much more data than there is.

    I haven’t noticed anyone responding to my physics challenge — whether there has ever been a natural phenomena where if the energy of the system increased, then the statistical variance of some measure proportional to energy decreased.

    The fact of the matter is that when energy is added to a system the impact is that the variance increases, so of course the events become more extreme.

    No exception to this rule has ever been offered. Something that comes close is the fact that fluctuations become more severe when entering certain critical phase transitions, independent on the sign of the temperature change. But on the other side of the transition, the fluctuations subside.

    The only question is whether the excursions into more extreme behavior is statistically noticeable given the change in energy..

  113. Eli Rabett says:

    Hi Webby

    If a system is driven by temperature differences between two components then if you add energy to the system by warming the cooler component only then the fluctuations and intensity will decrease

  114. Some empirical results on the Marine ABL are presented in a paper of Zeng et a.. The following figure shows some of that (I hope the link works)


    Fig. 2. Typical vertical profiles of the (left) relative humidity (RH) and (right) virtual potential temperature (θυ) for four different situations: (a) clear sky, (b) decoupling between ABL and cloud layer, (c) thin cloud layer, and (d) thick cloud layer. Superimposed in each profile are the sounding-derived ABL height (horizontal solid line) and cloud layer (shading)

    We see that relative humidity is typically 75-80 % at the lowest altitude shown and increases with altitude as absolute temperature decreases (potential temperature is nearly constant in the ABL). The boundary layer is so well mixed that the absolute humidity is relatively constant in it.

    Very close to the surface the relative humidity is essentially 100%, but very close means in that case heights so low that mixing by the eddies of the boundary layer have little influence. Essentially 100 % RH is certain at least within one mean free path of gas molecules from the surface. How far further that is true is difficult to tell based on general arguments.

  115. BBD,

    Pekka

    >> If we consider the resent years, certain uncommon patterns have dominated the state of
    >> the Pacific.

    Can we say that this is not a consequence of the increase in OHC and tropospheric temperatures over the last several decades, predominantly a result of anthropogenic forcing?

    No, we cannot say that, but neither can we say the opposite to the best of my knowledge.

    >> If one single reason is important, and it’s causal origin unknown, then the statistical
    >> significance of many observations is really weak.

    Is it really ‘unknown’?

    I do believe that it is.

    We see in the net discussions innumerable references to scientific papers that are supposed to prove the point favored by the person, who presents the reference. That’s done in highly cherry picking way as most scientific papers do not present certain results or even clear conclusions that are very likely to be true. Rather the majority of the papers present individual results that provide some very limited support to some hypothesis.

    Individual papers prove usually little, the full set of scientific results provides the best present understanding. Contradictory results are ubiquitous in that set of results, but some of those results have survived better further scrutiny than the others.

  116. My above comment has been corrected, but not fully to what it was meant to be. I forgot to add the slash also in the tag before “No, we cannot say ..”

  117. Okay, I think I guessed the wrong blockquote to slash. Is that it now?

  118. BBD says:

    Pekka

    No, we cannot say that, but neither can we say the opposite to the best of my knowledge.

    So the increase in OHC, SSTs and tropospheric temperatures has had no effect? I suspect this isn’t physically possible.

  119. BBD,
    I get the feeling that Pekka is suddenly turning into a frequentist 🙂

  120. Eli Rabett says:

    Pekka, the key, IEHO, is that there is a level at which CC holds, because this controls surface evaporation rates.

  121. Eli,
    I agree, and I wrote that RH is 100% very close to the surface. For most of the boundary layer the strong mixing by cell convection limits the absolute moisture to a lower level, when the air get mixed with air that has been at a higher altitude and lost moisture through condensation and precipitation. That can be seen in the pictures I show.

  122. BBD,

    Of course they have some effect, but I do not believe that anyone can draw well justified connection of the type you propose. Many things vary in the atmosphere. Some of the changes are causally related, some just happen to occur at the same time.

  123. On second reading I notice that I did probably misunderstood what Eli wrote above. Now I think that he refers to the level where 100% is reached that occurs in the cloud layer in the figures I linked.

    We must be careful in considering the energy balance condition. All fluxes must be determined at the same level. I have had some problems in figuring out, how that’s done in the papers of Trenberth and others.

  124. Joshua says:

    Anders –

    Clicked on your tweets – perhaps that Roberts post and Revkin’s related post might, at some point, make for an interesting thread.

  125. Joshua,
    Yes, I actually RT’d Revkin’s post because I did think it was interesting. I need to read it a bit more carefully, but it seemed to make some good points.

  126. John Hartz says:

    Obeservation: Although much of it is above my pay grade, the recent discussion on this thread has been both interestring and informatiove — due in large part by the fact the contributors have not laced their comments with snark. An adult discussion of the physics and chesmistry of how the atmosphere responds to climate change is indeed enlightening — even to a semi-climate science wonk such as myself.

  127. John Hartz says:

    ATTP/Joshua: Please identify and link to the Revkin’s and Robert’s posts that you have referred to. Thanks.

  128. JH,
    It’s this one. I do need to read it properly, as I just skimmed it, but I thought it seemed interesting.

  129. John Hartz says:

    In the context of the OP and the discussion thread, the following statement (my bold) caught my eye.

    “Our results show significant increases in heat waves and the number of hot days and warm nights, and at the same time declines in cold waves and extreme windy days in many urban areas over the last 40 years. We also find that the number of changes in precipitation extremes was modest, which is somewhat surprising as our previous work showed a predominance of increases in precipitation extremes in major US urban areas,” said lead research author Vimal Mishra from the Indian Institute of Technology Gandhinagar.

    World’s cities experiencing more heatwaves, study shows by John Vidal, The Guardian, Jan 29, 2015


  130. Eli Rabett says:
    Hi Webby

    If a system is driven by temperature differences between two components then if you add energy to the system by warming the cooler component only then the fluctuations and intensity will decrease

    Bunny, I understand that is the typical duhnihilist argument going from equator to pole. But cool the warmer component faster than the cooler component cools and then take both to the extreme of absolute zero and see what you get then. At some point the fluctuations have to decrease in the opposite direction. That is a general rule from thermal physics.

    They are thus arguing for an artificial sweet-spot,. So the fact that something artificial will need to be introduced to keep the warmer part from warming too much kind of violates the notion of a natural phenomenon. Or they are arguing for an inflection point.

  131. Michael 2 says:

    ATTP says “Given that 70% of the planet is ocean and an increase in temperature, without an increase in RH, would lead to enhanced avaporation, it’s hard to see how we can avoid specific humidity increasing. At the moment, it appears that we would expect RH to remain roughly constant. As I understand it, the only way we can avoid increased evaporation is for RH to go up.”

    Since sea surface temperature rise lags atmosphere temperature rise by a large amount, the average relative humidity of the Earth must go down during periods where the trend of atmospheric temperature is rising. Should it go the other way, where atmosphere is cooling while SST remains warm or continues warming because of mixing and inertia, the RH of the atmosphere will increase and quite a lot of precipitation everywhere ought to be expected.

    This in an important factor since a step increase in air temperature isn’t matched by a step increase in SST. As it has been observed by others, the boundary layer of air/water will always be 100 percent RH but by the time that air passes over land and the temperature rises, without additional water sources to feed it (California for instance), RH goes down.

    But I see your point, because so much of the Earth is ocean, even an unchanged RATE of evaporation (regulated by as-yet unchanged, or slowly changing, SST) will eventually saturate the warmer air with more water vapor even if it takes a little longer to do so.

    Even so, over land the air will warm abruptly and RH goes down.

  132. Michael 2 says:

    dhogaza commented “Have you ever heard of convection?”

    Yes. It has something to do with the little ovens called “convection ovens”. I don’t know any ovens that aren’t convection ovens so I’m not sure what makes them special. Perhaps your comment explains it, but perhaps you just ask some questions.

    “or noticed that Arizona’s monsoon season is late July-August when it is hottest and when warm, humid air from the Gulf flows over the state?”

    So what disturbs the Hadley cell to make this possible? Downflowing dry air cannot “monsoon”. And yet, clearly it does monsoon. Plain to see the boundary of the Hadley cell moves north allowing tropical weather patterns to intrude into southern Arizona. Why does it do that? Beyond my paygrade but I suspect seasonal changes in the jet stream distort the boundary, perhaps something to do with permanent cold in the Pacific Northwest and permanent hot in southern California, Mexico, Arizona and Texas.

  133. Michael 2 says:

    Pekka says “M2, Evaporation is expected to increase both directly as consequence of increased CO2 and as consequence of higher temperatures.”

    Well of course it is expected at least here 🙂

    I cannot think of any other place, except maybe SkS, that would list CO2 as a cause of evaporation (rather than heat).

    “Increased CO2 reduces net IR energy transfer out of oceans by making the atmosphere more opaque.”

    I consider the word “opaque” to be a poor descriptor since it is inherently binary; a thing cannot be more opaque or less opaque. It would be better to say more CO2 causes more infrared to be re-radiated back to the ocean almost immediately upon leaving the ocean, reducing net radiation, but not eliminating it, which is implied by “opaque”.

    “Increased temperature increases absolute humidity. That makes also the atmosphere more opaque”

    A positive feedback.

    “Increased humidity means also that the same net flow of air moves more latent heat, and that moving a fixed amount of energy requires less mass flow.”

    A negative feedback.

    “less net IR means that slightly more heat has to be transferred by convection.”

    Convection appears to be the primary transport. Since it has become more effective, the net feedback appears to be negative.

    “Some important weather phenomena like tropical cyclones get their violent energy from condensation of moisture.”

    Precisely my point all along — you need a heat sink otherwise you cannot have condensation (not for long anyway).

    “Thus it’s surely natural to expect that they get stronger with more moisture.”

    Yes, many people arrive at this conclusion. I am less sure of it. To be sure, you’ve added more “fuel” to the atmosphere but like any heat engine, if you don’t have a cold side, it doesn’t really do much for the engine just to have more fuel.

    “Their whole existence requires warm ocean water.”

    But that’s just the fuel. You need a temperature difference and you also need some sort of constraint like exists in a Stirling cycle engine. In the case of cyclones, the rotating air mass is self-constrained; centrifugal force helps keep a low pressure in the center of the cyclone or tornado, a fact that also triggers condensation keeping the engine going.

  134. John Hartz says:

    Micahel 2: You state:

    I cannot think of any other place, except maybe SkS, that would list CO2 as a cause of evaporation (rather than heat).

    If you find any instance of where CO2 is listed as a cause of evaporation rather than heat in an article posted on SkS, please let us know.

  135. John Hartz says:

    Here’s another well written macro-explanation of what’s causing extreme snowstorms such as Juno in the Notheastern Atlantic seaborad.

    Some of our readers out there may have friends, family members, office workers or political representatives who like to use winter weather as “proof” that global warming is a sham. Planet Experts has covered this before. Make no mistake, the planet is definitely getting warmer, but this is why “climate change” and “global warming” are two related but separate phenomena.

    Snowmageddon 2015: Why Global Warming Causes Blizzards by Pierce Nahigyan, Planet Experts, Jan 29, 2015

  136. John Hartz says:

    Here’s another well written macro-explanation of what’s causing extreme snowstorms such as Juno in the Notheastern Atlantic seaborad.

    Some of our readers out there may have friends, family members, office workers or political representatives who like to use winter weather as “proof” that global warming is a sham. Planet Experts has covered this before. Make no mistake, the planet is definitely getting warmer, but this is why “climate change” and “global warming” are two related but separate phenomena.

    Snowmageddon 2015: Why Global Warming Causes Blizzards by Pierce Nahigyan, Planet Experts, Jan 29, 2015

  137. John Hartz says:

    Here’s yet another factor to throw into the mix…

    Toxic smog billowing from China’s coal-fired power plants is making snowstorms in the US worse.

    How China’s Filthy Air Is Screwing With Our Weather by James West, Mother Jones, Jan 30, 2015

  138. Michael 2 says:

    John Hartz asks “If you find any instance of where CO2 is listed as a cause of evaporation rather than heat in an article posted on SkS, please let us know.”

    How many of you are in there? Why can you not simply write “let ME know?”

    Anyway, for that I’d have to spend more time there than I’m willing. It is not a scientific authority but it *is* the Vatican of global warming dogma. I name it because of its preeminent standing among warmists combined with what seems to be nearly perfect ineptitude at addressing skeptical concerns.

    What time I have available I’d much rather spend HERE where some arguments are scientific and persuasive. This site has members in the bubble but the site itself isn’t.

    I’m reminded of a Star Trek (STNG) episode where the universe is collapsing and at one point the starship Enterprise is larger than the known universe. It turns out to be a “bubble” that is shrinking. Strange that of all the STNG episides, this is one of the few that I remember reasonably well.

    http://en.wikipedia.org/wiki/Remember_Me_%28Star_Trek:_The_Next_Generation%29

    So what does the Bubble say? Increasing frequency and severity of storms.

    Observation? Maybe increased severity of storms, increased frequency is not observed, and good theoretical reasons exist for this.

    Consider a normal thermal plume. As it rises, at some point RH goes over 100 percent. Condensation takes place. But with that, heat is released which immediately increases air temperature and reduces RH and condensation stops. You need a method to quickly remove heat as it is released so that condensation can continue. A dramatic example is a tornado where heat goes up the tube (which is clear and non-condensing) while condensation surrounds the tube.

    A “more extreme” storm will scrape up more latent heat, discharging more energy into space than a “normal” storm. The result is that it takes longer to recharge — but the rate of recharge may be higher. The result of these factors is that the frequency of storm probably won’t change much.

    This item which relates to this discussion. I wonder why the authors chose a Carnot cycle engine rather than Stirling cycle engine.

    Abstract: Incoming and outgoing solar radiation couple with heat exchange at Earth’s surface to drive weather patterns that redistribute heat and moisture around the globe, creating an atmospheric heat engine. Here, we investigate the engine’s work output using thermodynamic diagrams computed from reanalyzed observations and from a climate model simulation with anthropogenic forcing. We show that the work output is always less than that of an equivalent Carnot cycle and that it is constrained by the power necessary to maintain the hydrological cycle. In the climate simulation, the hydrological cycle increases more rapidly than the equivalent Carnot cycle. We conclude that the intensification of the hydrological cycle in warmer climates might limit the heat engine’s ability to generate work.

    http://www.sciencemag.org/content/347/6221/540

  139. John Hartz says:

    Michael 2: You ask:

    How many of you are in there? Why can you not simply write “let ME know?”

    “We” are the people reading this thread.

  140. John Hartz says:

    Michael 2: You state:

    I name it [Skeptical Scince] because of its preeminent standing among warmists combined with what seems to be nearly perfect ineptitude at addressing skeptical concerns.

    Pelase cite an example of where Skeptical Science has not adequately addressed a “skeptical concern.”

  141. Michael 2 says:

    John Hartz writes “We are the people reading this thread.”

    Ah, okay, the Borg Collective. You have been assimilated. Resistance is futile. 😉

    http://en.wikipedia.org/wiki/Borg_%28Star_Trek%29

  142. Gator says:

    M2: Carnot cycle refers to a theoretical limit of conversion between heat and work.
    http://en.wikipedia.org/wiki/Carnot_cycle
    They are comparing the atmosphere to a theoretical limit; not surprisingly, the atmosphere is not a perfect heat engine.

  143. Michael 2 says:

    Thank you for the correction. I was probably thinking Otto cycle and did not realize until now that Carnot cycle is a theoretical engine.

    I learned something! It is a great day to be here.

    http://physics.stackexchange.com/questions/98966/maximum-theoretical-efficiency-of-internal-combustion-engine

  144. John Hartz says:

    Michael 2:

    Don’t count your chickens before they are hatched. You have only been partially assimilated. 🙂

  145. Pingback: Atmospheric Heat Engine | …and Then There's Physics

  146. Tom Andersen says:

    The best storm data on the planet seems to be the cyclone data set.

  147. Pingback: Matt Ridley on fossil fuels | …and Then There's Physics

  148. Pingback: Matt Ridley is wrong again on fossil fuels

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