Freeman Dyson: Well, this was about 40 years ago. At that time before the climate became a fashionable problem, before it became political, I used to go to Oakridge, which is the national laboratory which specialised in an ecological approach to climate. The head of the project there was Alvin Weinberg. He collected a group of experts there who were not just experts in fluid dynamics but experts in plants and soil and in the chemistry as well as physics, biology, all branches of science. They worked together putting a picture of the future of energy. It was called the Institute for Energy Analysis.
So I worked there for several summers and became reasonably well informed. At that time there was a competing group of experts working I think in Colorado who were experts in the narrow field of fluid dynamics who were doing climate models on computers. They were competing with us for public attention, and they clearly won the battle. They became the public spokesmen for the whole subject of climate with this very narrow point of view, working out numerical models of climate in great detail, paying no attention to the real world of snow and ice and all the complications of life and vegetation.
Freeman Dyson: What I see is the evidence is going very much in the other direction. Only the problem is that the public only hears one side of the discussion. For political reasons…I mean, it’s political effectiveness of this green lobby, the green political movement which has captured the whole discussion. The problem is not whether the climate is warming, we all know the climate is warming, the problem is: is that good or bad?
Sharon Carleton: What would it take to change your mind?
Freeman Dyson: Well, I think it would take a very serious program of investigating the beneficial effects of carbon dioxide, with the same sort of political push that has been devoted to the harmful effects. In fact carbon dioxide is making the world greener, and the public just doesn’t understand it.
Judith Curry: I’m talking about uncertainty, I’m saying we don’t know. I’m not saying I have any answers, I’m saying the other people, if they tell you they have an answer, don’t believe them. There’s massive uncertainty in this very complex subject that is not adequately accounted for when these people are spouting off their highly confident conclusions. I see more and more evidence that leads me to question the conclusions. The models are tuned to match preconceived ideas of how sensitive the climate is to increasing carbon dioxide. You can get whatever answer you want.
Garth Paltridge: The reviewer might have input but doesn’t necessarily get his way, and putting his name publicly on a document, especially on a politically sensitive document, raises the extreme likelihood that the public will assume he agrees with the thing in its entirety. There was much about that final report with which I disagreed, basically because it did as much as possible to ignore or hide the extreme uncertainty about the science of the business. The bottom line was that the whole thing smelt like a setup simply to make the political point that all those academicians, including a known sceptic, one of those horrible people, agreed with the document, so it must be correct and deserve reading.
Steve Sherwood: There wasn’t any evidence that we didn’t include, unless we thought it was not relevant or misleading. ……………
Don Aitkin: I see no reason why humanity should be worried by the increase in carbon dioxide. There is no good evidence to show that this is going to be bad.
Sharon Carleton: Do you think there’s any risk?
Don Aitkin: I think it’s about the same order of a big asteroid hitting the Earth.
Judith Curry: There is a potential for something bad to happen from greenhouse gases, but there are many possible dangers and you have to decide how you’re going to deal with it. Trying to prevent a possible danger, trying to prevent an asteroid strike or whatever, you have to pick your battles. And when you have a great deal of uncertainty, like we do with the climate change issue and a question of whether the cure is worse than the disease, the appropriate response is really try to increase the resilience of our societies. I think it’s a good thing for humans to tread lightly on the environment where they can, but there’s a lot of trade-offs.
So what we should be doing in terms of policy, I have no idea. If you go back to the 1950s or 1930s or even back to the 19th century, weather extremes were at least as bad, if not worse than current. And even the IPCC, they acknowledge this, there is no observational evidence of worsening extreme weather events. Sea level rise: it’s been rising for 10,000 years, get over it. The Arctic sea ice decline is unusual on the timescale of 60 years or so where we have good records, but on longer timescales, no, it’s not all that unusual. In terms of the Antarctic, two years ago there was record high Antarctic ice extent, and now there is a record low. This isn’t human-caused climate change, this is natural variability.
Andy Pitman: Judith Curry has been talking at length about the need to build resilience in human systems to make them as non-vulnerable or as resilient to climate change as possible, and I fully agree. It is absolutely clearly the case that extreme events are becoming more frequent and worse.
Sharon Carleton: But I thought the IPCC had actually said that there was no evidence that we were seeing more extreme weather events.
Freeman Dyson: Of course there are risks on both sides. It is certainly a question of risk management. But it’s very dangerous to only look at the risks on one side and not on the other. I think global warming is one of the minor questions compared with the destruction of the environment from other things like overfishing and the destruction of forests, all kinds of much worse things we should be worrying about.
Judith Curry: Okay, humans are contributing something to climate change. How much we don’t know. But even if you believe the climate models, all of the commitments made as part of the Paris agreement wouldn’t change the climate by more than one or two tenths of a degree by the end of the 20th century. If you think CO2 has less of an impact on the climate, then it would even be a smaller amount. So what is the point of thinking that if we do all this emissions reduction at great cost to the global economies and tell the Africans, ‘no, you don’t get grid electricity because we are worried about carbon dioxide’, at great cost to human development and economics, so that we can maybe prevent two-tenths of a degree by the end of the 21st century? What is the point of that?
Sharon Carleton: So is it worth risking? Do we just roll with the dice?
Judith Curry: Yes, it’s a values question. Whenever there is a warm period, they call it a climate optimum. The cold periods is when societies have struggled. So why are we assuming that the current warm period or a future period that’s even warmer is going to be somehow bad? Deciding and declaring that a warmer climate is somehow dangerous to me is totally unjustified. And then you have the solutions that are put forward to fix this so-called problem, they are completely inadequate for making any kind of a dent. So who’s in denial?
Andy Pitman: At the moment the planet is heading towards warming of, let’s say, four degrees. It might be 3.8 degrees, but it’s about four degrees, as business as usual. What Judith Curry is talking about is how much would we reduce that four degrees of warming if just the US cut its emissions, and that may well be about two-tenths of a degree. But there is no such model on the agenda. No one has ever suggested only the US would cut its emissions.
Just a short interuption …
USA have cut their emissions, while China and India are increasing hem at a greater rate than USA is cutting them.
As part of the Paris agreement, all countries are required to cut emissions, and if all those countries did cut emissions you would reduce the business-as-usual warming of about four degrees to about 2.8 degrees, which is a huge difference. It also shows that the level of commitment to reduce greenhouse gas emissions in the Paris agreement is not enough to reduce it from that four degrees down to below two degrees, which is what Paris aims to achieve.
Andy Pitman: I’m not an economist, but the things I’ve read in that area point to those countries that have taken significant steps to reduce CO2 emissions, like some European countries for instance, and also some US states like California, have absolutely not seen a negative impact on their economies, that a number of the European countries that have deeply cut CO2 emissions have seen economic benefit as a consequence. I think it’s just a total myth that you can’t re-engineer your economy to be much less carbon intensive and not get a significant benefit on your economy.
So how come industry is moving to areas which are increasing their contribution to atmospheric CO2?