Although I find this a rather uncomfortable topic, I thought it well worth highlighting an article by Piers Sellers in which he discusses his thoughts about climate change, given that he has just been diagnosed with Stage 4 pancreatic cancer. As an aside, Piers Sellers is a graduate of the University at which I now work.
It’s a powerful and poignant essay in which he, after thinking about the position he was in,
….found out that I had no desire to jostle with wealthy tourists on Mount Everest, or fight for some yardage on a beautiful and exclusive beach, or all those other things one toys with on a boring January afternoon. Instead, I concluded that all I really wanted to do was spend more time with the people I know and love, and get back to my office as quickly as possible.
As you might imagine, however, Watts Up With That has a post (archived here) objecting to a scientist using their dire personal health issue to promote their views about climate science; Science is supposed to be about reason, logic and evidence, not desperate appeals for sympathy. In my view, not only is this an entirely unreasonable interpretation of Piers Sellers’s article (although not as bad as some others that I won’t even bother Archiving) since Piers Sellers doesn’t say anything that isn’t widely accepted, by scientists and policy-makers, it’s also a simplistic interpretation of the role of science and scientists.
Researchers should, of course, aim to be objective and unbiased when doing their research and when presenting it in a formal setting. However, they have no obligation to do so when engaging with the public in their personal capacity. Not only are they both scientists and members of the public, what’s the point of investing in research, if those who understand it best are discouraged from publicly discussing the implications of what it suggests. As I’ve said before, I’m – of course – not suggesting that scientists/researchers should have some kind of special place when it comes to making decisions, I’m simply suggesting that the public benefits from experts expressing their views as to the significance of their research.
I won’t, however, say more about this aspect of the article (although feel free to express your views in the comments), but there was one thing in the article that I thought I would highlight. Piers Sellers says:
It’s doubtful that we’ll hold the line at 2 degrees Celsius, but we need to give it our best shot. With scenarios that exceed that target, we are talking about enormous changes in global precipitation and temperature patterns, huge impacts on water and food security, and significant sea level rise. As the predicted temperature rises, model uncertainty grows, increasing the likelihood of unforeseen, disastrous events.
It’s really this last sentence that I think is interesting and is maybe an under-appreciated point; although it is related to the uncertainty isn’t your friend point that both Victor Venema and Michael Tobis have discussed before.
We can think of what we’re doing as perturbing the natural greenhouse effect. The natural greenhouse effect essentially warms the planet by 33K. Our actions over the last 150 years, or so, has warmed it by about another 1K. Although our climate is clearly a very complex, non-linear, system, if the perturbation is reasonably small, we can have some confidence that the response will be linear, and that we can predict what will probably happen. Our confidence, however, decreases as the perturbation grows. As a rule of thumb, we might expect the response to become increasingly non-linear for perturbations of about 10%, or larger; i.e., warming of about 3K, or more.
So, one might reasonably argue that the closer we get to a perturbation of 3K, or higher, the harder it will be to confidently predict the response, and – hence – the more likely it becomes that we will encounter unforeseen, disastrous outcomes. That’s not to say that less than 3K will be fine, but simply that the larger the perturbation, the greater the risk of outcomes that we didn’t expect and that may have extremely damaging consequences. I think this is something that we should be taking into account, and it reminded me of the video below, which I’ve mentioned before, but which is worth posting again. The reason is mainly to highlight what Richard Alley says at 6:05
so when we look at climate change; best estimate; a little better; a little worse; a lot worse….the uncertainties are mostly on the bad side
...and Then There's Physics 
Thank you. 😉
Piers Sellers: As the predicted temperature rises, model uncertainty grows, increasing the likelihood of unforeseen, disastrous events.
I had missed that sentence. Thanks. A very important truth.
ATTP: Although our climate is clearly a very complex, non-linear, system, if the perturbation is reasonably small, we can have some confidence that the response will be linear, and that we can predict what will probably happen. Our confidence, however, decreases as the perturbation grows. As a rule of thumb, we might expect the response to become increasingly non-linear for perturbations of about 10%, or larger; i.e., warming of about 3K, or more.
I think I would have written this after my physics studies. 10% of the mean.
As an atmospheric scientist I would now tend to say: 2 times of the variability. What the relevant variability is depends on the problem at hand. For sea level rise it is the temperature on time scales of centuries and longer, which has not much variability. For changes in ecosystems the time scale is years to centuries. For agriculture it is days to a season.
Victor,
That’s a good point. I was thinking in terms of the response of the physical system, but you’re right that the magnitude of the impact likely depends on the magnitude of the change relative to the variability, which will vary depending on the system we’re considering.
You can insert a time in a YT video, like this:
1, Click on Share:
2. Click on Start
3. Enter the time:
You get this:
Piers Sellers’ article is also a good illustration of the fact that the moral concerns of climate scientists -just like the general population- are really quite mainstream.
There are no Earth-first radical ideologies to be found in Sellers’ piece, no partisan postures. Just the kinds of concerns for the next generation that pretty much all of us have -with the exception of the noisy fringe of activists who we know well.
Well are giving it our best shot via the Paris Agreement and when we have our first 5 yearly meeting regarding what we have managed to achive we will see how close we are to avoiding 3-4C as 1.5 to 2C is ver very unlikely to be achieved.
Come to think of it, and in the news today is China swamping Europe with a whole load of Steel that they did not need because their economy is slowing down and it is not longer needed by them. So due to all of this sort of thing going on it is difficult to know on short times scales if global CO2 emissions are slowing and even if they are will china’s economy pick up again and hence emit more co2 or will it grow and emit moe of something else entirely.
No short terms answers to any of these questions.
“As the predicted temperature rises, model uncertainty grows, increasing the likelihood of unforeseen, disastrous events.
That is unsubstantiated assertion and illogical at that.
If one actually knew that unforeseen events were likely, they would be neither uncertain nor unforeseen.
TE,
No. Did you think before you wrote that?
““As the predicted temperature rises, model uncertainty grows, increasing the likelihood of unforeseen, disastrous events.”
This tends to happen when a bunny heats things up. More thermal energy and it goes where it wants to. Basic physics.
This tends to happen when a bunny heats things up. More thermal energy and it goes where it wants to. Basic physics.
If you turn your oven on to 500F but leave the door closed, you can stare in through the window all day, but not much happens – no weather or climate. That’s because climate isn’t determined by molecular motion, but rather by the motion of ‘parcels’ of air.
Now, if you open the oven door, the relatively much colder kitchen air is displaced by the newly escaped oven air rising above.
The effect of doubling or even of quadrupling of CO2 just doesn’t significantly change the distribution of energy imbalance which is the main determinant of climate.
Temperature rise will occur with more CO2, but probably not much climate change.
Basic physics.
If you turn the oven on at 500 C with a dead duck in it what you get is an oil fire and the emergency services on your doorstep.
TE,
I’m going to just start deleting your comments. They’re really getting silly. Quadrupoling CO2 could increase average global temperatures by 6oC. If you think that won’t produce much climate change then you really should stick to sites that encourage such suggestions.
TE,
Just to clarify, by your definition, the climate during a glacial is essentially the same as during an inter-glacial?
Temperature is part of climate. If temperature changes, climate changes.
Temperature is not the only part of climate, however. And average global temperature does feed back into other parts of climate: cloudiness & types of clouds present, precipitation patterns, the temperature disparity between poles and equator, etc.
Windchaser,
Indeed. Something I hadn’t appreciated is that the average precipitation is expected to increase at something like 2%/K. However, this paper suggests that extreme precipitation events might increase by as much as 7%/K. If so, this would imply more of our precipitation is in the form of what – today – we’d regard as extreme events.
TE –
Take a pan of water. Bring it to the boil. See how it boils on low, medium, and high.
You’ll find it a lot more locally variable on high. Turbulent convection in fluids ‘n’ all.
Look, TE seems absolutely convinced that we can make a change similar in magnitude to the change between a glacial and an inter-glacial without producing much in the way of climate change. I don’t think we really need to discuss this further. I suspect we all have much better things to do.
For a sobering fictional portrayal of one of the coming catastrophes of climate change, take a look at: https://robertscribbler.com/2016/07/29/hothouse-2090-category-6-hurricane-a-grey-swansong-for-tampa/
We should be devoting most of our time to resilience, with an effort equal to or greater than that for World War II.
Pingback: 2016: A year in blogging | …and Then There's Physics