Inconvenient Climate Truths: From Extinction Theatre To Rational Debate
I published this post first on JuST THINK. To stay up to date, come tohttps://justthink.substack.com/ and subscribe for free!
In case you’d forgotten, we are all going to die.
Not in the obvious sense that each and everyone of us will eventually succumb to our mortal nature (after all, Silicon Valley keeps seeking an immortality pill or a way to upload our consciousness to the cloud). No, I’m talking about the extinction of the entire human species.
In case you had forgotten, the COP 27 climate change summit underway in Egypt will make sure to remind you that human extinction due to global warming is fast approaching. This, unsurprisingly, creates some hysteria: in Europe activists are blocking traffic and gluing themselves to masterpieces in art museums.
The motto of JuST THINK is that whenever you want to understand something, you should look at the numbers and … well .. just think; don’t take anyone’s word for granted, not even the experts’. Especially when they tell you that a consensus has been reached, and the science is settled.
So let’s try to make sense of the clash between the “consensus” that claims the science on climate change is settled, and some highly qualified scientists who insist that it is not. Let’s listen to both sides of the debate. This post summarizes my findings, many of which will surprise you. It builds on a series of blogs I published a year ago. It’s going to be a lot less comfortable than repeating the same litany as everybody else — but a lot more satisfying.
Let me say this up front: The climate is changing — it has been changing since earth was born. The evidence is all around us, and almost nobody claims otherwise. But the science is not settled, and the term “climate change denier” is thrown around too liberally to suppress debate on a number of uncomfortable questions.
Climate change: what we know and what we don’t
One of the contrarian voices is Steven Koonin. When I told friends I was reading his book “Unsettled”, they warned me Koonin is an untrustworthy hack with a hidden agenda and a poor grasp of the issues, in the pocket of fossil fuel industries. A dangerous denier.
Another denier! Except that Koonin is a theoretical physicist who served as Undersecretary for Science in President Obama’s Department of Energy and has extensive experience on climate science. So it’s worth reading the book, comparing his views to those of notable “believers”, and assessing the arguments. The first takeaway is that it’s important to recognize what we know about climate change and what we do not:
- The planet is getting warmer, and greenhouse gas emissions due to human activity are contributing. That much we know. We do not know, however, how much of the change in climate is attributable to human activity, because:
- Human emissions play a smaller role compared to other determinants of the climate, such as variations in solar activity, volcanic activity and fluctuations in the height and density of cloud coverage;
- Climate models are unable to capture these other factors with sufficient precision; hence forecasts of how the climate will change — including due to human emissions — are subject to a very high degree of uncertainty;
But while these uncertainties are recognized in the body of the official climate reports (which run into thousands of pages), they are ignored in the executive summaries in favor of simpler messages that get further simplified and dramatized by the media. In his book Koonin documents this with plentiful quotes from the climate reports.
Climate scientists do it with models
The climate debate is based on model estimates and forecasts. So, how good are these models?
Like economists, models disagree. Koonin notes that the global average temperature forecasts coming from the many models used by the IPCC (Intergovernmental Panel on Climate Change) can differ by as much as 3 degrees centigrade; in other words, the margin of uncertainty is as large as the temperature increase these models are forecasting.
The chart below, from the Summary for Policymakers of the latest IPCC report, shows the projected increase in global surface temperature compared to the 1850–1900 average. You see that even just the “very likely range” is quite large. Notice also that the chart starts in 1950 — rather convenient, as it turns out.
Source: IPCC Report: Climate Change 2022: Impacts, Adaptation and Vulnerability
Even more troubling: Climate models can’t explain the 1910–1940 global warming episode, which was of a similar magnitude to what we have experienced since 1970, as you can see from this second chart, taken from NASA. This is quite a shocking indictment of the models: If they can’t replicate the past, why should we think they can predict the future?
What do you mean by “data”?
The data here are not hard facts, they are model estimates. In 2013, the data showed that global temperatures had remained flat over the previous 15 years. The Economist, which printed the chart below, called it “among the biggest puzzles in climate science just now.” How do you solve the biggest puzzle? Well, two years later that same data were revised to show that temperatures had been rising all along.
Source: The Economist, March 2013
Think about it for a moment. This is not uncertainty on how to estimate global temperatures in the 1500s. This means that just a few years ago we did not really know what the recent global temperature actually was. At the same time we are asked to believe that precise temperature estimates for the past 2000 years and decimal-point forecasts for the next 200 are indisputable, settled science.
There is nothing wrong with using model estimates. Gauging the planet’s temperature is hard — you can’t just stick a thermometer under its tongue. But we should acknowledge the significant degree of uncertainty in the debate and in decision-making.
Extreme views on extreme weather
“Climate change is causing more frequent and more severe extreme weather events and natural disasters.” Countless media reports, UN pronouncements and even scientific papers routinely open with a statement along these lines, presenting it as an unchallenged fact.
But is it true?
To contrast Koonin’s skepticism I turned to a podcast by Professor Adam Sobel, a Columbia University climate science expert who specializes in extreme weather attribution — figuring out whether hurricanes, heat waves etc. are caused by climate change. Sobel and Koonin are at opposite ends of the spectrum. Sobel is very critical of Koonin, and Koonin has very little confidence in weather attribution studies. Comparing their views, here is what I found:
- Both agree that our understanding of the link to climate change varies considerably depending on the type of extreme weather event. We are more confident that climate change is causing more heat waves and contributing to more severe forest fires, but we do not really understand whether climate change is likely to lead to more or fewer hurricanes, tornadoes, and winter storms.
- Koonin stresses that there is no significant trend in the global number of cyclones or in the number of US hurricanes; and no scientific evidence that global warming causes more hurricanes. He adds that we do not know whether floods and droughts have been increasing, decreasing or remained stable. We simply do not know.
- Have heat waves become more frequent? Probably. Sobel however notes that when we get a heat wave that pushes the maximum temperature to say 45°C, we cannot reject the idea that without climate change we would anyway have gotten a heat wave of 44°C: since the globe has warmed by 1°C, this has raised the baseline, but heat waves would happen anyway.
- Koonin provides very interesting data showing that high temperatures have not become more extreme, at least in the US: since 1900 the lowest temperatures in the US have gotten less cold, but the highest have not gotten hotter. You can see this in the chart below, from from Chapter 6 of the USGCRP (US Global Change Research Program) Climate Science Special Report (2017), part of the Fourth National Climate Assessment. The panel on the left shows the coldest temperatures have increased; the panel on the right shows the warmest temperatures have been broadly stable since 1950, at the same level as 1900 and markedly lower than in 1930–40.
Source: USGCRP Climate Science Special Report (2017)
But wait a second: if the highest temperatures have not increased, why does the IPCC say heat waves have become more frequent? It turns out there are various definitions of a heat wave. The Environmental Protection Agency for example defines it as a period of two or more days when the daily minimum temperature adjusted for humidity is higher than the historical average. Ok, maybe this squares the circle: we are not experiencing more frequent bouts of hotter-than-ever temperatures, but we do get more heat waves because the coldest temperatures have risen.
These two scientists from opposite ends of the climate debate show more agreement than disagreement on what we actually know — which makes the stark difference in their positions quite remarkable. Keep this in mind as you read further.
My conclusion: as the planet has gotten warmer, the risk of weather events directly linked to higher temperatures, like heat waves and forest fires, has probably increased; blaming every hurricane and flood on climate change has no scientific basis; the risk of catastrophic weather events might be increasing, or it might not — science does not yet have an answer.
Uncertainty and risk
Given that climate science is subject to enormous uncertainty, what should we do? Here we see a fundamental disagreement.
Sobel argues that uncertainty should not be an excuse for inaction. We know temperatures have been rising and we know human activity has contributed. True, we do not understand everything that is going on, and the models leave a margin of uncertainty; but that means things could get even worse than the models predict, and therefore we should err on the side of caution and take rapid action.
Koonin counters that uncertainty counsels a more cautious approach. Yes, temperatures have been rising and human activity has contributed. But our understanding is so limited that we don’t actually know how much human activity has contributed, nor whether the corrective actions we plan will have any meaningful impact compared to the underlying natural changes.
There is no objective right or wrong here, it’s a legitimate disagreement on how to deal with uncertainty.
Costs and benefits
How we factor in uncertainty matters because reducing emissions quickly carries significant costs. A 2020 study estimates that keeping the global temperature increase below 1.5°C would leave 80 million more people in poverty by 2030 (Figure 2). The energy crisis triggered by Russia’s invasion of Ukraine shows that reducing reliance on fossil fuels before we make further progress on renewables implies slower growth and lower incomes.
I am optimistic about technological innovation. But here is a reality check: with all the advances in renewable energy technologies, for the last 30 years the share of fossil fuels in total global energy consumption has remained stubbornly above 80%. (Meanwhile global energy consumption has risen by over two-thirds.) In the next 30 years, it must drop to less than 30% to meet the targets of the International Energy Agency’s ‘Net Zero’ scenario. At the current pace of energy transition, we are going nowhere fast.
We need to be realistic and admit that a rapid transition away from fossil fuels would involve substantial costs. Advanced economies would have to downsize their lifestyle, and emerging markets would have to accept a much slower improvement in living standards — and a slower reduction in global poverty means more people will die. Given the substantial costs involved, we need a cost-benefit analysis; and in this analysis, the uncertainty on our climate change forecasts does matter.
Moreover, a cost-benefit analysis should consider the full range of consequences of global warming. Stanford’s Bjorn Lomborg has recently pointed out that the reduction in the number of deaths due to extreme cold far outnumbers the higher deaths due to extreme heat. Cold kills way more people than heat; hence the rise in global temperatures is saving lives. It might kill us all in the long run — but scientific reports and media headlines focusing exclusively on more heat deaths are dishonest.
The role of scientists
This is a crucial issue, and the one I find most disturbing. Contrarians like Koonin and Lomborg excoriate the majority of climate scientists for encouraging the dogmatic apocalyptic pronouncements of media and policymakers, even though they are full aware of the enormous uncertainty underlying the science. The thousands of pages of the IPCC reports recognize all the uncertainties; the summary for policymakers sweeps them away and sounds very definite; media and policymakers predict an impending apocalypse and most scientists nod in agreement.
In the podcast, Sobel explains why in a surprisingly candid way. He argues that scientists should play down the uncertainty when they communicate to policymakers and the public. He worries that disclosing too much uncertainty would lead to inaction. He thinks scientists know enough to conclude that early and decisive action against climate change is necessary, and have a responsibility to convince the public and politicians to go forward — and this requires simplifying the message.
I find this attitude troubling. If there are important trade offs to be made in a situation of uncertainty, the responsibility for the decision rests with the public and policymakers; it should not be pre-empted by scientists.
Instead, the scientists’ attitude is: if we give them full information, people cannot be trusted to make the right decision; therefore we should convey only the information that will push society onto what we believe is the right path.
Inconveniently revealed preferences
This attitude is not only unethical but also counterproductive. It undermines the public’s trust in science and experts; and by stifling the scientific debate it hinders the discovery of better solutions and the diffusion of best practices. Today young scientists know that if they want to push a line of research not fully aligned with the accepted climate change “consensus”, they will face enormous difficulties in obtaining research grants and academic jobs. The science is “settled” the way elections in North Korea are settled. This makes it much harder to advance our scientific understanding of the climate, which is still woefully inadequate.
Moreover, this attitude inevitably backfires:
- Policymakers keep telling us we are heading for extinction; but they have barely managed to agree on emission targets that they themselves recognize are insufficient to “save the planet”, and can’t meet even those perfunctory benchmarks;
- Most people keep driving, flying and running heating and air conditioning the way they always did;
- When an energy crisis comes around, Germany fires up its coal plants and the US administration begs Saudi Arabia and Venezuela to pump more oil.
In economics we call this revealed preferences: it’s your actions that show what you really want. Here they suggest that nobody really believes we face extinction — or at least nobody really wants to pay the price to avoid it.
Here is my conclusion — and I know many of you will disagree. The climate is changing, and this poses a challenge. There is a lot we don’t understand, and the uncertainty might well hide apocalyptic risks. Or it might not.
We should reduce emissions because they warm the globe and they pollute. We should keep improving renewable energy technologies; it’s the smart thing to do, and eventually we’ll run out of fossil fuels. But reducing emissions is not costless — particularly for the large share of the world population that still lives in poverty. We need a transparent debate in terms of cost-benefits and risk management.
Instead, media and policymakers have adopted a strategy of scaremongering, playing up apocalyptic predictions while hiding the uncertainty of data and forecasts and downplaying the cost of the proposed actions. Too many scientists have become willfully complicit. This is backfiring: people are unwilling to make serious sacrifices and governments are unwilling to adopt the measures they claim are necessary. It makes it harder to identify the best response to the climate challenge and it further undermines the public’s trust in science and institutions. If we truly want to address climate change, we need a far more honest approach.
Now unglue yourself from that Chagall and let’s make some progress.