trust vs science (yet another global warming catfight)

[Sam_Stone]

@wolfpup

I must say, Sam, that was one of the worst misrepresentations of IPCC statements that I’ve yet seen from you. I’m disappointed. I’m not going to go through every single misrepresented item in that long diatribe but I’ll address the major ones.

For starters, you state that “the biggest ‘positive feedback’ posited for large values of climate sensitivity is water vapor. What’s the consensus on what has actually happened with water vapor?” and then you provide a quote from the IPCC about large uncertainties regarding stratospheric water vapor.

The overwhelming proportion of water vapor effect is in the troposphere, not the stratosphere. Here, the operative factor is basic physics – the Clausius Clapeyron relation – that says absolute water vapor will increase in direct proportion to temperature. This constitutes the most powerful single feedback in the climate system, and there is no uncertainty about it whatsoever. Yet for some reason you chose to provide a quote from the IPCC about water vapor in the stratosphere, which is an entirely different beast, and then go on a page-long rant about how we apparently don’t know anything about water vapor!

Mea Culpa on that one. I missed that it was referencing stratospheric water vapor. You’re absolutely correct.

You make several statements about uncertainties regarding cloud cover. Yes, but this is not – and has never been regarded as – a major influence in the climate change balance and there’s been no systematic trend; clouds have both positive and negative feedbacks depending on altitude, and on balance are expected to continue to be a relatively small (and probably consistent) negative feedback.

According to the IPCC, cloud feedbacks are not one of the larger components of global climate sensitivity, but they have a major effect on the latitudinal distribution of warming, and therefore have a major effect when trying to calculate the impact of global warming. They could make the difference between climate change mostly warming the high latitudes, which might actually be beneficial for moderate warming, or for warming to mostly affect tropical climates, which could be very bad. And there is still low confidence in our ability to model and predict cloud response to warming.

From here:

It is beyond question that the increased cloudiness prevailing over the warmer portions of the Pacific has a strong effect on the surface energy budget, which is fully competitive with the importance of evaporation. Determination of SST, however, requires a consistent treatment of the top-of-atmosphere energy budget, and cannot be effected with reference to the surface budget alone. This does not preclude the possibility that other cloud feedback mechanisms could have a profound effect on tropical SST, and in no way implies that cloud representation is inconsequential in the tropics. Meehl et al. (2000) illustrate this point when they show how a change from a diagnostic prescription of clouds in the NCAR atmospheric GCM to a prognostic cloud liquid water formulation changes the sign of net cloud forcing in the eastern tropical Pacific and completely alters the nature of the coupled model response to increased greenhouse gases.

Bolding mine. It seems to me it’s pretty hard to model the impact of warming in the tropics when one of your major uncertainties could ‘completely alter the nature of the coupled model response to increased greenhouse gases’.

Don’t forget where I’m coming from on this. I’m not using any of this to claim that global warming isn’t happening. The whole point to my message was to show areas where there was still no consensus on what the science says, to break the myth that the entire global warming debate is one that has ‘the consensus of over 90% of scientists’ on one side and ‘deniers’ on the other. What I am trying to show is that the issue is very complicated, with varying degrees of consensus over various parts of it - some small, some large. And also that there is still much uncertainty remaining in the model responses, as is shown by the wide spread in projected warming values that the IPCC is willing to commit to.

You claim the predictions of drought got it all backwards because California should be getting more rain, not less. Completely wrong. The IPCC statement is about central North America, not the west, and it’s not a prediction, it’s an observational statement about what has actually occurred since 1950.

My assumption was that ‘Central North America’ meant mid-latitudes, as opposed to southern or northern regions.

You somehow see fit to characterize the summary statements on the urgency of climate change mitigation issued by the US National Academy of Sciences, the national science academies of the United Kingdom, Brazil, Canada, China, France, Germany, Italy, India, Japan, Mexico, Russia, and South Africa, along with the American Association for the Advancement of Science and virtually every major science body on the planet as being politically motivated. This is nothing short of the worst of the denialist conspiracy theories and I’m pretty sure you don’t really believe that, but if you do, our conversation here is done.

I went to some length to say that it is NOT a conspiracy. My point was that when 90% of your members are liberals, you are likely to discount or even deny the cost of higher taxes, giving up national sovereignty to international organizations, etc. It’s bias, not conspiracy.

I happen to believe that political leaning is a big factor in the climate debate. The fact is, the proposed solutions to climate change are all policies that tend to align with what the left prefers anyway. Or do you think it’s a coincidence that the global warming debate seems to have polarized people down political lines and not scientific ones?

This is not conspiracy, it’s a real and valid consideration. If I believe that high energy taxes are dangerous, and you believe that higher energy taxes will, at worst redistribute wealth from oil barons to the common people, then clearly we are going to weight the cost of those tax increases very differently. If you believe that strengthening extra-national institutions will help the cause of social justice and I believe they are a serious threat to liberty, then obviously we are going to weight the cost of those differently.

So even if both of us agreed completely on the science, we could still completely disagree on what should be done about it due to our political differences. And in fact I think that’s what’s really going on in the climate change debate. The debate over the science has been polarized and obfuscated by activists on both sides because it’s become a proxy war in the endless political struggle between the right and left. And that’s a shame, because it’s an issue that is complex enough on its own without being distorted by politics.

And yes, both sides do it. On your side, when the global temperature doesn’t rise as much, or if there’s a quiet period in storm activity, your side is very quick to remind everyone that short-term weather is not indicative of long-term climate changes. But every time there is a drought or a hurricane, activists on ‘your’ side run out and start yelling that this is obviously a result of global warming. And people on the other side do the same thing in reverse.

Now, I’m not claiming that you specifically are doing this, or even that the global climate science community is doing it. I’m talking about the advocates on both sides who are not scientists (and a few scientists who are also activists).

[quote]
You seem to try to refute the greatly improving accuracy of global climate models by claiming “[the scenarios] aren’t science. The IPCC calls them ‘storylines’.” Like “storylines” was supposed to imply “fairy tale”, or something. The concept of RCPs is that one of the major uncertainties in climate change projection is what our future emissions will be. The science can only operate based on specific GHG levels. The RCPs are intended to offer a range of projections based on different mitigation scenarios which helps establish danger levels and mitigation targets. The “storylines” are a holistic view of the entire socioeconomic pictures in the different scenarios, and you’re right, that’s not hard science, and no one said it was. But the underlying models are.

I am fully aware of that. You are conflating the models with the scenarios. The scenarios are things like “In this scenario, the world moves to an information economy, and there is less cross-border migration”, or “In this scenario high economic growth causes X and Y”. They are ‘pictures’ of the future world, and they are highly speculative. The IPCC ameliorates this by having many different scenarios to cover a number of possible outcomes, then modelling the climate response to the CO2 emissions predicted under each scenario.

This type of activity falls into the category of, “Hey, it’s the best we can do.” No one can predict the future, so you predict multiple futures and hope that you’ve covered all your bases. But there’s no reason to believe that any of these scenarios are even remotely correct. Our history of being able to predict the future past a couple of years in the future is dismal.

As I said, where’s the ‘peak oil’ model? Or are we pretending that peak oil is no longer an issue at all? If so, when did that happen?

And no, coming up with scenarios for how society might evolve is not science. It’s not remotely science, even if scientists are doing it. It’s simple prognostication and extrapolation based on the opinions of experts. It’s a set of assumptions to be used to come up with some numbers that can be input into models to predict the future.

You claim the IPCC AR4 predicted beneficial effects. Absolute garbage. What has been said on occasion is that warming itself, disregarding all the extreme weather and biosystem consequences, may temporarily increase some crop yields in some northern latitude regions, but that these isolated effects will not be sustainable before lack of adaptation to climatic and ecological effects reverses them. Most other areas, especially Africa and tropical regions notably the most vulnerable to the consequences of crop failures, will see only negative impacts.

Sorry, it looks like that info was in AR3. I searched AR4, and they reference a graph from AR3 and contrasted it with the Stern Report’s impact assessment, which does not show the net benefit. You can see that here: https://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch20s20-6-1.html

Note that the graph marked IPCC 2001(b) which definitely shows net benefits for moderate warming, although only one study on that graph extends it to 2.5 degrees.

While I was searching for the info in AR4 and AR3, I also found this meta-study:

http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.23.2.29

Figure one shows a graph of estimates impacts from 14 different studies. All but one shows net global economic benefits for warming up to 2.3 degrees.

Does this look like it will be beneficial?

Those are overall impacts include environment. I was referring to the estimates of human economic benefits and costs, which aren’t referenced on that graph at all.

An example of some of the possible benefits: Opening the Northwest Passage would substantially lower the cost and energy requirements of shipping between many countries. One of the reasons why you can have net economic benefits is that the countries that are hurt the most have lower economic contributions globally, while the countries that might see net benefits have a disproportionate effect on the global economy. A slight inccrease in crop yields in the northern ‘food belt’ would have a large economic impact, even if more people in the tropics might be hurt by global warming.

This was not an argument saying moderate global warming is a net good - just that it might result in net positive economic benefits. A very different thing.

Also, I should admit that the latest assessment is more pessimistic about the effect of global warming on crop yields than earlier assessments. But this is yet another area where there is a lot of uncertainty.

My rebuttal to your “complex adaptive system” argument stands – your argument is irrelevant when there is a long-term consistent forcing that drives the system in a particular direction.

We have no idea if it will drive it in a particular direction over anything but the short term. The transient response is certainly positive, but we have no idea what the result will be after various feedbacks kick in - especially after a period of multiple iterations. Complex systems can respond to shocks by over-correcting, by collapsing into a new state, or by having a series of complex responses. We could see warming, followed by climate responses that ultimately result in cooling, followed by further responses that cause warming again. Or we could see the rise of CO2 sequestration mechanisms (plant growth, algae blooms, etc) that begin to scrub CO2 from the atmosphere at a faster rate. If we stop adding to CO2, those mechanisms could wind up driving CO2 below recent historical levels.

After all, CO2 in the atmosphere has fluctuated substantially in the past, without any human contribution. CO2 is part of the complex climate system and does not exist in a fixed steady state in the atmosphere.

Of course, these responses could be a long time coming and not be useful to humans. Or maybe they’ll happen over a generation or two. Or maybe the long term response will be to correct, but the short and medium term response could be a positive feedback that makes things worse for the next couple of hundred years. This stuff is frustratingly hard to understand and predict, and scientists have a history of underestimating the difficulty of dealing with complex systems. This is a chronic problem in macroeconomics, for example.

Now, I’m not saying that this is going to happen, just that we don’t know enough to validate your claim that a forcing must always push a complex system in one direction.

In this case, the constantly increasing thermal energy being accumulated by the planet. You seem to find contradictions in the fact that specific regional changes and specific timings are hard to predict yet we have confidence about long-term global impacts. There is no contradiction – this is a lot like the weather vs. climate argument. As in that argument, a lot of the misunderstanding stems from the failure to recognize that, for instance, global climate models can make reliable global projections despite having relatively poor spatial granularity, or otherwise treating spatial and temporal details statistically.

What it looks like to me is that the very short term is unpredictable (weather), the medium term is more predictable (annual and decadal climate), but the long term becomes less predictable as the long-term global feedbacks enter the mix.

If there was some specific point that you feel I didn’t address let me know. If you just want to rant and promote denialism then I’m not likely to participate. After the way you distorted the statements of the IPCC I honestly don’t know any more how interested you are in a factual debate.

I’m not trying to distort anything. I wasn’t trying to provide a comprehensive assessment of what the IPCC is saying. I was specifically addressing the argument that ‘the science is settled’ or that there is a strong scientific consensus over every aspect of the global warming debate. There is not. There are still serious uncertainties in the climate models, and future projections of human impact require projections of human economy, population migration, technology breakthroughs and other social factors that are totally outside the expertise of climate scientists and for which the track record of prediction is quite dismal.