The questions of Mr. Beyer to Dr. Curry on the Committee Hearing of The President’s UN Climate Pledge were interesting. As seen in previous post both used the same word, but with a different meaning. I ended with Dr. Curry’s reaction. For completeness I repeat it below:
Okay, the confusion is this: scientifically the term “climate change” means a “change in climate”. And it changed for the past four billion year or so. This whole issue of human caused climate change is a relatively recent notion. So climate is always changing and it is going to change in the future. The issue is how much of the change is caused by humans. We don’t know. We don’t know what the 21th century holds. Climate change may be really unpleasant and that may happen independently of anything that humans do. My point is that we don’t know how much humans are influencing climate and whether it is going to dominate in the 21th century. Given that we don’t know this, we are still going to see extreme weather events, whether or not humans are influencing the climate. This is what I am talking about, that we really don’t know how the 21th century climate is going to play out and that we should figure out how to reduce our vulnerabilities whatever might happen and that includes extreme weather events that are going to happen regardless whether humans are influencing climate change.
This gave rise to following reaction from Mr. Beyer:
All sciences are contentious. We continue to learn and must be humble all time about what we know. But it seems to me very much sticking your head in the sand, to look at all the evidence of what has happened with global warming in the last 30 years. By the way, the debate whether 2004, 2009 or 2014 is the warmest year seems silly when we know when 10 of the last …
So he seems to think that admitting we don’t know and not indisputably blaming climate change on humans, equals sticking our head in the sand. It seemed a bit strange when I heard it, but when looking back at my own past, it is definitely something that I can understand. This probably comes from his perception of the science. No room for uncertainty and science is getting better and better. But we are talking about a science with huge (unreported) intrinsic uncertainties from studying a unique, chaotic system with limited high quality data available.
The debate over whether 2014 is or isn’t the warmest year on record is wrongly framing the issue. It shows a simplistic view of the situation. There is not one, but several temperature data sets that try to estimate the average temperature of the Earth. “Estimate”, because nobody is able to set an exact average temperature of the Earth and there are many efforts. The alarm he is raising comes from focusing on that specific dataset (in my eyes the least reliable one).
But as I said, I can understand his position. I have been there. When I was a believer I thought there was only one temperature of the Earth and that scientists were able to measure that correctly and accurately. How could I ever think otherwise, the media tells about the temperature of the Earth and that the scientists are sure that something is wrong with it. It never occurred to me that the average temperature of the Earth is notoriously hard to determine, especially with surface measurements. I never could imagine how much issues could influence the result or how some of the records change after the measurements. I had no idea about UHI, incomplete spatial coverage, changing stations, only few thermometers further you go in the past,…
How many years had the highest temperatures in last decades is in fact not the question. The question is whether these are caused by human emissions and by how much. And whether that is dangerous or not. A temperature increase is not proof of it being caused by humans. It is even a more interesting question politically: if this warming is predominantly natural, then slashing CO2 emissions will not help much and it would be better to reduce vulnerabilities for extreme events that will, without a doubt, will keep happening in the future. With our without our influence.
As pointed out in previous post, the apparent contradiction between the two views is imho merely a nuance. Dr. Curry is talking about a changing climate, whether caused natural or by humans or both. Mr. Beyer is talking about (dangerous) human caused climate change. A simple statement like “climate change is real” will get confusion in the conversation and leads to perceiving that the testimony is “just full of internally conflicting facts and opinions”.
Then Dr. Curry delivered the bombshell:
Okay, the climate has been warming since the 1700s, since we came out the ice-age. We don’t know what caused that warming in the 18th and the 19th century. It is not attributed to humans, so there are other things going on in the climate system that has been contributing to a warming over several centuries. We can’t blame all of this on humans. And we don’t know how all it is going to play out in the 21th century. We just don’t know.
This, I think, is a strong argument against a dominant influence of anthropogenic greenhouse gases. When temperatures are increasing since the the depth of the Little Ice Age, then there is a trend before the 1980s-1990s temperature increase that is not explained by the influence of human emissions and “there are other things going on in the climate system”. Indeed, when looking at the current trend from the 1850s we see temperature risings of about 30 years, alternated with decreasing/stabilizing trends of 30 years. It would be strange to attribute human influences on temperatures in the 1980s-1990s, yet forgetting about the rise since the 1700s.
Mr. Beyer on the other hand was not impressed:
We had a a vice president who is willing to argue for enhanced interrogation and torture on the 1% chance that Al Queda might some day get a nuclear weapon. And we do nothing because there is a greater than 1% that climate change …
Which is beautifully countered by Dr. Curry:
There is nothing in my testimony that says we do nothing. What is proposed is ineffective, it isn’t going to do anything. Even if the US is successful at meeting 80% reductions by 2050, this is going to reduce warming by about a tenth of a degree centigrade. It is not going to do anything. I am saying, we need to acknowledge that and rethink how we are going to deal with the risk from future climate change whether it is caused by humans or natural processes. That is what I am saying.
Remarkable that, even after reading out loud the actions Dr. Curry think should be taken, he still believes that she is pleading to do nothing?!?!? It shows me he deeply believes in the theory and solely focused on this specific solution, in order to consider other actions as doing nothing.
Trust, yet verify 
It seems that Dr Bayer does not distinguish between what “is” and what “ought to be”. That is the positive and the normative. He rejects an experts understanding of the “is” due to trying to justify the “ought”.
But Dr Curry is not clear on policy justification – and might not have been invited to give testimony if she was more explicit. If climate change is highly uncertain AND we know that mitigation policies will be ineffective (as few, if any, countries will achieve the required emissions reduction policies AND mitigation policies are largely useless, so most targets will not be achieved) then the resources expended on mitigation will be wasted.
I suggest we should follow the lead of others. The medical profession realize a need to separate diagnosis from treatment. Identifying the ailment (and the extent of that ailment) from the symptoms does not usually give the cure. They also realize that medicines have risks, are not always effective and getting the dosage right can be difficult.
That suggests that before policy is enacted, we should obtain a more accurate diagnosis of the nature, extent and likelihood of climate change before doing anything. Like in medicine, to start treatment without first having some expectation of it being of net benefit to the patient is immoral. In other words, the pressure should be on the climatologists to refine the accuracy of their models. But that would mean learning from past predictive failures, whether of the hiatus in warming, or the signals of a big problem.
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Thanks Kevin. Nicely put.
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