I think I need another break!

I think I probably need to take another short break from all of this online nonsense. I’ve recently been commenting on Bishop-Hill and had been quite enjoying it. I’d been accused by other commenters of being patronising and condescending, but that was somewhat intentional. I knew that if I took it seriously, the responses would just wind me up too much. Then, I made the mistake of taking it seriously, and the wheels fell off.

It related to a lengthy discussion about the significance of chaos. It’s clear that our ability to forecast weather events more than a few days in advance is very difficult, if not impossible. This is a consequence of the system being non-linear and, essentially, chaotic. The precise evolution is very sensitive to the initial conditions and since our models can never set the initial conditions with infinite precision, our ability to forecast specific events decreases with increasing time. If you want to know more, you can read the Realclimate post by James Annan and William Connolley, which says,

Although ultimately chaos will kill a weather forecast, this does not necessarily prevent long-term prediction of the climate. By climate, we mean the statistics of weather, averaged over suitable time and perhaps space scales (more on this below). We cannot hope to accurately predict the temperature in Swindon at 9am on the 23rd July 2050, but we can be highly confident that the average temperature in the UK in that year will be substantially higher in July than in January. …… models based on physical principles also reproduce the response to seasonal and spatial changes in radiative forcing fairly well, which is one of the many lines of evidence that supports their use in their prediction of the response to anthropogenic forcing.

This is really all I was trying to point out in the discussion. I was also trying to stress the importance of the boundary conditions. Our climate’s boundary conditions are essentially the albedo, the solar insolation, and the composition of our atmosphere (the greenhouse effect). These boundary conditions broadly set the overall of state of our climate, which is essentially a consequence of energy conservation (these boundary conditions will set the equilibrium temperature at which we are losing as much energy as we gain).

It is possible for internal variability to influence some of these boundary conditions, but we have little evidence to suggest that it can have a significant impact in our current climate state. There’s a suggestion that it can have a small impact that may last a decade or so (see this post) and there is some evidence to suggest that some of our past climate changes were internally forced. However, we don’t expect (at the moment) internal variability to play a significant role (it might, but the evidence for this is weak). So, even though the system is inherently chaotic doesn’t mean that it can simply shift into an entirely new state – the overall state of our climate (the conditions averaged over a suitable time interval) are largely constrained by the boundary conditions.

Well, this discussion didn’t go well. Apparently the boundary conditions are irrelevant in a chaotic system, and why was I so focused on energy conservation anyway (because it’s a fundamental law of physics, maybe). My tolerance – which had already been strained – disappeared when someone (who shall remain nameless) popped along to point out that I was an idiot because it is indeed possible for non-linear dynamical systems without boundary conditions to simply shift into an entirely different state. Well, yes, because it’s a non-linear, dynamical system WITHOUT BOUNDARY CONDITIONS! Telling me I’m an idiot because a system that is not really comparable to our climate can do something our climate probably can’t do, is a remarkably poor rebuttal.

Anyway, I need to finish working through some lecture notes, finish working on a paper (which happens to be on a non-linear, dynamical system – I hope I know what I’m doing) and take a few deep breaths. I think I’m now being moderated on Bishop-Hill as my comments weren’t appearing. I haven’t gone back to check recently, so they may have appeared now. I’m kind of hoping Andrew Montford will ban me. Not so that I can then complain about it, but so that I can stop wasting my time there. I’m well aware that I don’t have much self-control, so Andrew would be doing me a favour if he were to do so.

Posted in Climate change, Climate sensitivity, Global warming, Personal, Science | Tagged , , , , , , , | 97 Comments

What does Judith mean by natural?

Gavin Schmidt recently addressed Judith Curry’s 50:50 argument in a Realclimate post. In Judith’s response (which doesn’t really say much) she finishes with,

I do regard the emerging realization of the importance of natural variability to be an existential threat to the mainstream theory of climate variations on decadal to century time scales. The mainstream theory views climate change as externally forced, e.g. the CO2 control knob theory. My take is that external forcing explains general variations on very long time scales, and equilibrium differences in planetary climates of relevance to comparative planetology. But it does not explain the dominant variations of climate on decadal to century timescales, which are the time scales of relevance to policy makers and governments that are paying all this money for climate research.

So, unless I’m misunderstanding Judith she really is suggesting that natural variability could significantly influence warming on timescales as long as a century. Although Judith doesn’t specify, I’ll assume that the implication is that it could provide as much as half of the warming over the course of the instrumental temperature record – since 1880, so longer than a century but let’s just work from there.

So, I thought I’d try to put some numbers to this to see how plausible it is that natural variability could play a significant role in the warming since 1880. Let’s set down some basic numbers. We’ve warmed by 0.9oC since 1880. In the absence of any other changes, this would increase the outgoing flux by 3 Wm-2 (\epsilon 4 \sigma T^3 dT). However, we still have an energy imbalance of about 0.5 Wm-2, so that suggests – assuming that the energy imbalance in 1880 was small – that we’ve seen an increase in radiative forcing of 3.5 Wm-2 (well forcings plus feedbacks). The change in anthropogenic forcing over the same time interval is between 1 and 3 Wm-2, with the uncertainty largely a consequence of uncertainties in the aerosol forcings.

So, when Judith suggests that a large part of the warming on century timescales could be natural, what does she really mean? There are two possibilities that I can think of and I’ll try to explain them below.

  1. Half of the change in radiative forcing is natural and half anthropogenic – i.e., about 1.75 Wm-2 each.
    • This would suggest that the aerosol forcing has to be on the high side.
    • If we assume that half the warming is natural and half anthropogenic, then it suggests that the feedback response to natural warming is significantly higher than that due to anthropogenic warming (since the anthropogenic forcing is unlikely to be less than 1 Wm-2).
    • If half the warming is natural and half anthropogenic, then in fact the TCR would be between 1 and 2oC and the ECS would be between 1.25 and 2.5oC (since the anthropogenic forcing is between 1 and 1.75 Wm-2 and the planetary imbalance would be 0.25 Wm-2).
    • In some sense, this possibility doesn’t really make much difference as it would simply imply that a large part of the anthropogenic warming has been masked by a potentially large negative aerosol forcing.
  2. The alternative is that Judith means that half the warming is natural and half anthropogenic and, consequently, that half the feedback response is natural and half anthropogenic [i.e., f = (3.7 Wm^2 - x)/2 where x is the anthropogenic forcing]. Let’s consider 3 different possibilities, low, high, and medium anthropogenic forcing.
    • The anthropogenic forcing is around 1 Wm-2 (very large aerosol effect), and the feedback to natural and anthropogenic warming is around 1.25 Wm-2 in each case.
      • This would suggest that the feedback is quite high since the natural and anthropogenic warming contributions are around 0.5oC each.
      • In this scenario the TCR would be around 1.9oC and the ECS would be around 2.5oC. Again, it would seem to be a scenario in which aerosol forcing is masking a lot of anthropogenic warming and the long-term warming would be in line with IPCC scenarios.
    • The anthropogenic forcing is around 3 Wm-2 (very small aerosol effect), and the feedback to natural and anthropogenic warming is around 0.25 Wm-2 in each case.
      • The feedback is very small. This would appear to make it difficult to explain long-term natural warming since this would seem to require that the feedback exceed the Planck response.
      • The TCR would be around 0.6oC and the ECS would be around 0.7oC which would suggest that the equilibrium response to the doubling of CO2 would lead to less warming than CO2 alone (overall feedbacks would have to be negative).
    • The anthropogenic forcing is around 2 Wm-2 (average aerosol effect), and the feedback response to natural and anthropogenic warming is around 0.75 Wm-2 in each case.
      • The TCR would be just less than 1oC and the ECS just about 1oC, so suggests that a doubling of CO2 would, in equilibrium, be associated with no feedbacks. This seems odd, since the initial assumption results in the feedback response being positive.
      • The feedback response to the natural warming is quite a bit smaller than the Planck response due to the natural warming. This would seem to make long-term natural warming quite difficult. Presumably natural warming can only be long-term if the feedback response exceeds the Planck response.

So, I’ve thrown this together a little fast and when I was thinking of this there were other factors that I’d thought of, but have now forgotten. From what I can see, there isn’t an easy way to construct a plausible scenario in which natural variability can have played a significant role in the warming over the last century or so. Again, this isn’t me saying that it can never do so, just that given the information we have for the last 100 years or so, and the state we’re in today, there doesn’t seem to be an easy way to construct a plausible scenario. If others can think of one, or can add other reasons why it’s implausible, feel free to do so.

Posted in Climate change, Climate sensitivity, ENSO, Global warming, IPCC, Judith Curry, Science | Tagged , , , , , | 133 Comments

Oh no, now I need to eat my words!

Okay, not really, but I might need to change them. Something that I’ve been stressing here is that internal (natural) variability can’t produce long-term warming. The reason being that it just moves energy around the climate system. If it’s not associated with some kind of change in radiative forcing, then if it heats the surface, the extra energy will be lost quickly, and if it cools the surface, the energy will be recovered quickly. For a system already in equilibrium, internal variability will simply cause the temperatures to vary about the externally determined equilibrium temperature.

I have, however, been made aware of a recent paper (thanks Victor; some people just don’t know how to stick to the script) that shows that it may be more complex than this. The paper (Top-of-atmosphere radiative contribution to unforced decadal global temperature variability in climate models by Brown, Li, Li & Ming) uses 36 pre-industrial control runs from the CMIP5 ensemble, to investigate how decadal variability in the top-of-the-atmosphere (TOA) flux influences surface temperatures. As I understand it, all these runs are unforced, so all the variability is internal (natural) and not forced.

The main figure is probably the one below. The two largest-magnitude warming decades and the two largest-magnitude cooling decades were selected from each of the 36 controls runs. In each case, they also determined the TOA flux for each of the decades that were selected. What they found was that warming decades were associated with a mean net TOA flux of -0.06 Wm-2 (upward orientated, so negative means gaining energy), and the cooling decades were associated with a mean net TOA flux of +0.06 Wm-2. So, even though this variation is internal, the warming is not simply associated with a movement of energy around the climate system, but is also associated with a net TOA flux that increases the total energy in the system. Similarly – but in reverse – for cooling decades. The paper also illustrates that about half the warming (cooling) in each of these decades was associated with the net TOA flux.

Figure showing temperature trends and TOA fluxes from unfroced control runs (Brown et al. 2014).

Figure showing temperature trends and TOA fluxes from unfroced control runs (Brown et al. 2014).


So, this seems to be an interesting result : internal variability isn’t necessarily simply associated with energy moving around the climate system, it could also associated with a net TOA flux. The paper indicates that this is mainly a consequence of small changes (0.1%) in the albedo that temporarily counteracts the change in the outgoing long-wavelength radiation.

The one question, though, is how significant this is with respect to recent warming. The paper addresses this, saying,

From the years 1955 to 2010, 0–2000 m ocean heat content accumulation suggested that the mean QTOA over this period was ~0.27 W/m2 (due mostly to external radiative forcings, F) [Levitus et al., 2012]. This study has shown that in extreme episodes of decadal scale unforced T change, mean TOA imbalances were on the order of ± ~0.06 W/m2 averaged across all GCMs (the most extreme imbalances observed were ± ~0.2 W/m2, Figure S4). This would imply that in certain circumstances, unforced variability in QTOA may have been able to modulate the long-term forced imbalance by ~22% (~74% in the most extreme circumstances) over the course of a given decade. Currently, however, measurements indicate that the energy imbalance at the TOA is between 0.5 and 1.0 W/m2 [Abraham et al., 2013; Trenberth et al., 2014]. At this magnitude, unforced QTOA variability would only be able to modulate the background forced imbalance by ~6–12% (~20–40% in the most extreme circumstances) over the entirety of a given decade.

So, over the course of a given decade it could modulate the forced imbalance by more than 50% when the imbalance is less than 0.5 Wm-2. However, given that the imbalance today is probably around 0.5 Wm-2 or greater, even in the most extreme scenario, internal variability will probably only be able to modulate the imbalance, today, by about 40%, at most. Of course, one should remember that this could both increase and decrease the imbalance, and – if I understand the paper correctly – is unlikely to extend beyond about a decade.

Even though this paper indicates that internal variability may not be only associated with moving energy around the climate system, I don’t think this means that internal variability can – by itself – be associated with long-term (multi-decade) warming, or cooling. I thought I might lay out some reasons why. Of course, these are just how I understand it, so if others disagree or want to elaborate or clarify, please do so.

  • Unforced, climate model control runs do not show evidence for multi-decade trends associated with internal variability.
  • Even though internal variability may not be only associated with moving energy around the climate system, this is still the process that triggers the warming or cooling. Since the available energy is finite, the process is self-limiting.
  • There is little evidence to suggest that internal variability played a significant role in past climate variability. Maybe, more correctly, in most cases we can associate past changes to our climate with external triggers or changes in external forcings.
  • As I understand it, the main reason for the change in the TOA flux is because of changes in albedo, presumably driven by changes in cloud cover. One might think that this could feedback on itself and consequently produce longer-term warming or cooling. Water vapour is, however, quite sensitive to temperature changes and so when the cycle reverses, the changes in water vapour and clouds should reverse and the system should evolve back towards to its pre-warming/cooling state (I may not have explained this all that well, so if someone can do a better job, go ahead).
  • The annual variation in global temperature is actually greater than the kind of variations being considered here. If this kind of variability could produce long-term warming, then that would suggest that the same should apply to the annual variations.
  • If internal variability can drive long-term warming, it would suggest that our climate is quite sensitive to small changes. This should then apply to changes in external forcings too (increased CO2 concentrations, for example), but might also imply that if it were that sensitive to small changes, we wouldn’t be here to have this discussion.

Given the recent interest in the role of internal variability, I thought this might be something interesting to post about. I don’t, however, think it really changes anything with respect to the significance of internal variability (and it is only one paper) and have laid out some ideas why, above. Of course, if others disagree or have other thoughts, feel free to make them through the comments.

Posted in Climate change, Climate sensitivity, ENSO, Global warming, Science | Tagged , , , , | 133 Comments

A thought experiment

To follow up on my – possibly poorly titled – post from a couple of days ago, I thought I would pose a thought experiment. This is entirely unrealistic and is just intended to, maybe, illustrate what I was trying to get at in the earlier post. Of course, it may fail dismally, or may just be too unrealistic to make any sense, but I’ll give it a try.

Consider the following scenario. We start with the planet in energy balance and then we emit, in a short space of time, a large amount of CO2 that increases atmospheric CO2 concentrations. Afterwards, we fix our emissions to maintain, but not increase, this higher atmospheric CO2 concentration. This increase will produce a change in anthropogenic forcing. Consider also that at the same time the Solar forcing increases by an amount greater than the increase in anthropogenic forcing. Given these two increases in external forcing, we will warm and – one might argue – that we will be mostly warming because of the change in solar forcing.

Now imagine that at some point in the future, the Solar forcing drops back down to what it was at the beginning, so that there is now no net change in solar forcing. Also, imagine that this happens at a time when the increase in temperature exactly compensates for the increase in anthropogenic forcing (and associated feedbacks), so that the system is again in energy balance.

So, we have a situation where the only change in forcing is anthropogenic and in which the system has warmed so as to retain energy balance. Is the warming :

  1. Mostly – or all – natural.
  2. Mostly – or all – anthropogenic.
  3. Both natural and anthropogenic.
  4. Neither.
  5. It’s just too complex to really describe in such a simple way.
  6. Stop writing posts that don’t make any sense and just confuse everyone.

Okay, there’s my thought experiment. Remember, it’s not meant to be realistic and is just an attempt to maybe illustrate what I was trying to get at in my earlier post. It may not succeed in doing so and – just to avoid confusion – I’m really not trying to argue that changes in solar forcing can’t warm us (i.e., if you think that the point I’m trying to make is that there is no such thing as natural warming, you’d be wrong).

Posted in Climate change, Global warming, Science | Tagged , , , | 88 Comments

There’s no such thing as natural warming!

Okay, not quite, but bear with me. This post is really just a response to those who seem to be suggesting that half of the warming between 1970 and 2000 could be natural, rather than anthropogenic. See my earlier post or Nic Lewis on Bishop-Hill. I’m going, here, to assume that those who suggest that half the warming in the last few decades of the 20th century could be natural, mean that it was due to some process internal to the climate system (as it can’t have been the Sun and can’t have been volcanoes). It’s this that I would argue doesn’t make sense and that, therefore, in our current situation, there is essentially no such thing as natural warming : it is all anthropogenic. I’ll try to explain why – some may disagree, but this could be an interesting discussion nonetheless.

So, here’s my reasoning. What we’ve done through burning fossil fuels over the last 100 – 200 years is to add so much CO2 to our atmosphere that we’ve produced a radiative forcing of about 2 Wm-2. A consequence of this is that it has taken our planet out of energy balance, so that we are receiving more energy than we’re losing. We are therefore gaining energy, some of which will heat the surface and raise the surface temperature. The increase in surface temperature increases the amount of outgoing energy and reduces the energy imbalance, and this rise in temperature will continue until we return to energy equilibrium.

Therefore, the fact that we are warming is entirely a consequence of our actions. If it wasn’t for us burning fossil fuels and increasing the atmospheric CO2 concentrations, we would not be warming (or, at least, not by much). So, that we are warmer today than we were in the past is entirely a consequence of anthropogenic influences and anyone who claims that half of the recent warming could be natural, should go and learn – or brush up on – their basic physics.

Okay, so the above is clearly quite a strong statement and there are some caveats. The Sun can clearly play a role, but it’s relatively small. Volcanoes can too, but they tend to produce cooling. Additionally, natural variability can also play in role in our warming, but what it does is change the rate at which we warm, but can’t really warm in its own right. In other words, this variability means that sometimes we will warm faster than at others. This doesn’t change, however, that the reason that we’re warming is entirely anthropogenic. Given this, however, one could define the long-term trend as the anthropogenic component, and variations about this trend as the influence of natural variations.

So, let’s then consider the possibility that natural variability doubled the rate at which we warmed during the period 1970 – 2000 : i.e., that half of the warming was natural, and not anthropogenic. If you go to the Skeptical Science Trend Calculator you’ll discover that the trend for this period was about 0.16 degrees per decade. If half is natural, the anthropogenic warming trend is then about 0.08 degrees per decade. If you then consider the period 1970 – 2014, the trend is still 0.16 degrees per decade. We’ve, therefore, now had 44 years with a trend of 0.16 degrees per decade, so if the long-term trend is actually 0.08 degrees per decade, we will very soon need to have a multi-decade period (almost 50 years) with no warming.

However, if we continue to increase our emissions, we’ll continue to move the planet further and further out of energy balance. So, those who are arguing that half of the warming between 1970 and 2000 was natural are essentially suggesting that we will have about 50 years of no warming, despite the planet moving further and further from energy balance. I think that’s physically implausible, even impossible. However – and here’s a challenge – if anyone can give a physically plausible explanation for how half the warming between 1970 and 2000 was natural, they’re welcome to try.

I’ve actually been thinking about a post like this all day, but it was a comment from Fred Moolten that motivated me to go ahead and write this. Fred says,

confusion on the part of the authors between the capacity of natural variability to affect the rate of warming from anthropogenic forcing and the role of natural variability as a source of warming in its own right.

I think this is the crucial point. There is a difference between natural variability being able to influence the rate at which we warm (it can) and its ability to warm in its own right (it can’t, or not by much). If people could understand this distinction, I think it would resolve much of the confusion.

Posted in Climate change, Climate sensitivity, Global warming, Judith Curry, Science | Tagged , , , , , , | 106 Comments

A “hiatus” in some people’s “skepticism”?

There’s a new paper doing the rounds of the blogosphere, called Varying planetary heat sink led to global-warming slowdown and acceleration. Judith Curry has a post about it. The basic result of the paper is that the “missing heat” is going into the deep parts of the Atlantic because a salinity variation is allowing warm water to sink rapidly. That sounds plausible, but I don’t really know enough to judge. The reason it’s generated some interest seems to be because it suggests that the “hiatus” will last another decade or so, and because it suggests (although this appears to only be in the press release) that only half the warming between 1970-2000 was anthropogenic (or due to global warming).

The paper concludes with

The next El Niño, when it occurs in a year or so, may temporarily interrupt the hiatus, but, because the planetary heat sinks in the Atlantic and the Southern Oceans remain intact, the hiatus should continue on a decadal time scale. When the internal variability that is responsible for the current hiatus switches sign, as it inevitably will, another episode of accelerated global warming should ensue.

Many seem to ignore the very end of that sentence and focus only on the part that says the hiatus should continue on a decadal time scale. Now, the paper seems to have gone through the historical records (including the Central England record) and found some kind of 60-70 year pattern of warm and cool phases, and is then arguing that we’re in some kind of cool phase now and that it will last another decade or so, since it has existed for about 15 years already.

One issue I have is that it is very likely that none of the cool phases in the past were coincident with the planet being significantly out of energy balance – as we are now. Even though we are in this supposed cool phase, we are still warming at something like 0.1 degrees per decade (which is something else the paper rather failed to point out). It’s possible that we could sustain this slowdown for another decade or so, but if we continue increasing our emissions, that would imply that we could remain in a cool phase with slow surface warming even when the energy imbalance is > 1 Wm-2. I find that somewhat implausible, but I may well turn out to be wrong.

Although I find the possibility that the “hiatus” could continue for more than another decade, or longer, a little unlikely, there is a claim in the press release that I find rather strange. It says

Rapid warming in the last two and a half decades of the 20th century, they proposed in an earlier study, was roughly half due to global warming and half to the natural Atlantic Ocean cycle that kept more heat near the surface.

When people say things like this, it makes me think that they don’t really understand anthropogenic global warming (AGW). AGW is simply the fact that we are increasing atmospheric greenhouse gas concentrations (GHGs) which then act to trap outgoing radiation, producing an energy imbalance, and increasing the energy in the climate system. There isn’t really some special anthropogenic mechanism that simply heats the surface. The surface warms because some of this extra energy heats the surface, increasing the surface temperature, which then reduces the energy imbalance.

On the other hand, its very likely that variability means that sometimes the surface will warm faster than at other times. Therefore one could define the anthropogenic (global warming) contribution as the mean long-term trend, and the natural contribution as being variations from this mean. If we consider the period 1970-2000, the Skeptical Science Trend Calculator suggests that we were warming at 0.16 degrees per decade. If half of this is global warming and half is natural, that would suggest that the global warming contribution was 0.08 degrees per decade. If so, that would suggest that over about a 60 year period, the trend should be 0.08 degrees per decade. However, this would imply that the trend since 2000 would have to be about 0 degrees per decade, which it isn’t. In fact, if you go back to the Skeptical Science Trend Calculator, the trend from 1970-2014 is also about 0.16 degrees per decade. So, if half the warming between 1970 and 2000 was natural, and we’ve been in a cooling phase since 2000, how can the 1970-2014 trend be the same as the 1970-2000 trend. It doesn’t really make sense.

So, as far as I can tell, the press release has a claim that isn’t in the paper and that doesn’t really make much sense, and the conclusion about the hiatus continuing for another decade or so is really just based on identifying some kind of 60-70 year cycle in the historical records – none of which contain periods really comparable to what we’re going through today. If I remember correctly, there was a massive outcry when the press release for the Marcott et al. Holocene temperature reconstruction paper rather overplayed the significance of part of their reconstruction. I wonder if the same people will be similarly shocked by the, apparently, unsupported claims in this press release? Don’t bother answering that question. I suspect we all know the answer. And, to be honest, I don’t really care. I do wish people wouldn’t overplay the significance of their papers in press releases, but they do and it’s really a systemic problem, rather than just a few individuals.

Posted in Climate change, Climate sensitivity, ENSO, Global warming, Judith Curry, Science | Tagged , , , | 100 Comments

Salby again!

After my last encounter on Bishop-Hill, I had a thought that I might simply avoid commenting there. However, when someone suggested that Rupert Darwall was a perceptive chap, I couldn’t resist pointing out that this was only true if regarding complete nonsense as having merit, qualified as perceptive. For context, Rupert Darwall recently wrote an article defending the – unpublished – work of Murry Salby, who happens to think that the rise in atmospheric CO2 is natural, and not anthropogenic. Well, he is very obviously wrong. My comment, however, lead to a new Discussion thread where I was challenged to show why Darwall and Salby are wrong. I tried, but I don’t think I managed to convince anyone there.

The problem I have is that showing that Murry Salby’s ideas are wrong is extremely easy. Consider the figure below. It shows how much CO2 we emit through burning fossil fuels, how much is absorbed and emitted by the oceans, and how much is absorbed and emitted by the biosphere (of which we’re also part). What’s fairly clear is that both the oceans and the biosphere absorb more than they emit (we don’t really absorb any as we’re not currently creating fossils, or – at least – not nearly fast enough). If the oceans and biosphere are absorbing more than they emit, then they very clearly cannot be the source of the increase in atmospheric CO2 and – in fact – are absorbing almost half of what we emit. The rise in atmospheric CO2 is, therefore, all us. To illustrate how well Bishop-Hill gets this trivial concept, there is a Bishop-Hill post that attempts to mock Bob Bindschadler by pointing out that the oceans and biosphere emit much more than we do, while failing to point out that they then absorb more than they emit.

Source : Fig 7.3, IPCC AR4

Source : Fig 7.3, IPCC AR4


You can even do more. The isotope ratios (C14, C13, and C12) tell us that the source must be old biological organisms (fossils). The reduction in atmospheric oxygen tells us the source is something being burned. There are multiple lines of evidence that show that Murry Salby’s suggestion that the rise in atmospheric CO2 is natural, is complete and utter nonsense.

So, here’s the conundrum I have. Bishop-Hill is just a blog and it’s also a free world. People can say whatever they like and if they want to promote silly ideas, that’s fine. Under normal circumstances I would simply ignore it – there are plenty of blogs spouting nonsense about climate science that I happily ignore. However, this is not just any old blog, it is run by someone (Andrew Montford) who has quite a high-profile, in the UK at least. He appears on the radio, on television, writes articles for magazine, and is quoted in newspaper articles. Yet, he appears not to understand, or accept, what is a trivial – but crucial – aspect of this topic. If he were honest, the next time he’s asked to talk about this topic in the media, he might respond with : “Sorry, maybe you should find someone else. I don’t understand this very well.” Maybe, also, the next time he writes a post mocking Julia Slingo – the Met Office’s Chief Scientist – he should consider the possibility that the reason he doesn’t get mocked more often is that decent people don’t mock those who have trouble understanding really simple concepts. I really do think we need a better class of climate “skeptic”.

Posted in Climate change, ClimateBall, Global warming, IPCC, Science | Tagged , , , , , | 74 Comments