Have you heard of Unsettled, the new book about the climate by Steven Koonin? If you follow climate issues you soon will. Koonin is under attack by climate activists as a “climate denier” (which he isn’t) and is being cheered by climate deniers as a scientist who has shown that human-caused climate change is a hoax (which isn’t accurate either).

So what, exactly, is Unsettled about? Having read it carefully, here is how I would describe its thesis: the science on climate change has been distorted and cherry-picked by the media and by groups with a reason to sensationalize the issues and make our climate knowledge seem more certain than it actually is. The book is meant as an antidote, demonstrating how tentative our knowledge of the workings of climate is, and how important factors besides human activities probably are. In Koonin’s view, we don’t yet know enough to know whether there is any real urgency around reducing greenhouse gas emissions.

Koonin is careful to cite his sources, and I think his science is sound, but I don’t accept his conclusions. Koonin looks at the scientific evidence and sees slow, inevitable change, with little urgency for action now. I look at the same evidence and see the potential for a catastrophe unless we take immediate action. In what follows, I will summarize Koonin’s arguments and then explain where we differ.

Koonin is a cheerleader for the scientific process, and he wants more emphasis put on the uncertainties in our scientific knowledge. He is a PhD physicist who has done a lot of work with computer modeling. His own modeling work has mostly involved the interactions of subatomic particles, but he has taken a strong interest in atmospheric modeling as well. In any case, he is well aware of the weaknesses inherent in complex computer models (such as the ones that are the basis for our understanding of the future of our climate). He devotes a whole chapter to the workings of the climate models and their limitations.

I feel a certain kinship with Koonin, who, like me, is interested in exploring the interesting details revealed when you dig into big sets of data. While my efforts have involved much more limited issues than the climate, some of my previous blog posts have reflected this interest in data. Examples include my coverage of Covid cases at Kendal relative to other retirement communities, my exploration of voter demographics here and elsewhere, and my analysis of energy usage on “peak alert” days.

So I appreciate what Koonin is doing but, at the end of the day, I come out with different conclusions than he does.

Unquestionably, the world is warming, and human-generated CO2 is involved. Koonin has no problem with some of the basic premises of those who worry about climate change. Yes, humans are adding C02 to the atmosphere; and yes, the globe is warming. Sea levels are rising. Koonin accepts all of that, and he clearly presents the data that shows it.

Koonin also accepts the science behind the reports of the International Panel on Climate Change (IPCC), which constitute the main scientific basis for the Paris Agreement and the “COP” series of international meetings, including COP 26, which is happening in Scotland as I write this.

Koonin’s complaint is that the media (and, to some extent, the scientific community as well) has presented climate issues as well understood, when in fact they are full of uncertainties. Here are some examples.

Global warming: “The real question is not whether the globe has warmed recently, but rather to what extent this warming is being caused by humans.” (p. 44) Huge amounts of energy arrive at the earth from the sun every day, and an almost equal amount is sent back into space. If the amount arriving exceeds the amount leaving, the earth warms. The changes in trapped energy due to greenhouse gases affect only about 1% of this vast energy flow. Are our atmospheric models sufficiently good to accurately show the impact of human actions, given this low level of effect? Koonin thinks they aren’t, and that means we just don’t know the degree to which humans are causing global warming.

Curbing greenhouse gas emissions: Koonin emphasizes that CO2 levels will continue growing “in any scenario short of ceasing all emissions”. He doesn’t think zero emissions can be achieved, and he doesn’t think carbon capture can be implemented on a large enough scale to make a difference. He calls zero emissions “a practical impossibility”. (p. 75) Given those assumptions, Koonin concludes that atmospheric CO2 can only increase.

Sea level rise: Koonin accepts that sea levels are rising, but the rate of rise varies from year to year (globally, it has been over 2mm in some years and under 1mm in others). It’s unclear, Koonin argues, whether the rate of rise has been affected by human activities or not, since rising levels with similar variability have been occurring for many decades. We don’t fully understand what drives these variations. And the mechanisms of local variations in sea level rise (as opposed to those affecting the entire planet) are even harder to understand. Koonin lists many factors that contribute to these levels, such as changes in ocean currents, erosion of nearby land, weather patterns, and so on. He calls for “clear and unbiased communication of these nuances” so that we can be prepared if sea level rise becomes a serious threat; and we won’t be prepared “if we insist we already know all the answers.” (p. 166)

Why isn’t the public hearing about the uncertainties? A major theme in Unsettled is the lack of public awareness of how uncertain the science around climate change actually is. It’s not that it is being covered up: Koonin points to dozens of places in the IPCC reports (and others) where significant uncertainty is acknowledged. But, he complains, the public is barely aware of this.

In Koonin’s view, this situation has arisen because many of the actors involved in informing the public have ulterior motives. Koonin devotes a chapter to this issue. He faults the media for its focus on the sensational and the lack of scientific background of many reporters. He faults politicians, who try to stir up the emotions of their constituents by exaggerating either the urgency of the climate situation or the possibility that it is a “hoax”. He faults scientific institutions, such as the National Academy of Sciences, for overstating the certainty of our understanding of climate change. He faults individual scientists, who are trying to secure grants and tenure by creating misleading publicity around their work. He faults climate-oriented organizations and activists who need to create a sense of urgency in order to raise funds and exert political pressure.

What should be done? The last section of Unsettled describes the actions currently being discussed at the IPCC meetings and elsewhere, and whether these are the right actions to focus on. The IPCC’s approach is based on the Paris Agreement goal of limiting warming to 1.5 to 2 degrees C by eliminating greenhouse gas emissions by 2050. Koonin criticizes the IPCC approach on three main counts: it doesn’t clearly specify the baseline from which emissions are to be reduced, it assumes we know that greenhouse gases are the main factor in warming, and it assumes that warming beyond 2 degrees will be detrimental. Koonin has problems with all three, and he argues that eliminating greenhouse gases will be impossible in an era of global growth of both population and per capita GDP, since both of those factors increase the demand for energy.

Koonin considers two approaches besides greenhouse-gas reduction that could help control global warming. One is “geoengineering”, in which a haze (analogous to that created by a large volcanic eruption) is introduced into the atmosphere to reduce the amount of incoming sunlight. The other is removing CO2 from the atmosphere, either via plant and forest growth or via carbon-capturing technology. Koonin concludes that neither one is likely to be practical and acceptable, but because “extreme weather events show little sign of an imminent climate catastrophe, there’s time to figure all that out.” (p. 242)

Ultimately, Koonin thinks the most likely path forward is for us to simply adapt to climate change. Koonin uses the analogy of adapting to earthquakes in California. People know earthquakes will happen at some point in the future, and they take precautions: building houses in ways that make them safer in an earthquake, keeping an emergency stock of food and water on hand, and so on. If we know the world will be hotter in the future, we can prepare for that situation.

To summarize, Koonin’s general view of climate change seems to be that we need to be much more aware of how much uncertainty there is in the science; until we have better data, we won’t know to what degree human activities are contributing to the warming. We don’t need to view climate change as a “crisis” because it will probably happen very gradually and we will be able to adapt.

Where I part company with Koonin. I think Unsettled does a good job of exposing the uncertainties in our knowledge of the climate, but I feel it is flawed in its treatment of some of the science, and in its overall conclusions.

First, it fails to address some of the important scientific ideas involved in thinking about climate change. One is the idea of temperature-sensitive “tipping points”—such possibilities as methane release from permafrost, sudden dislodging of Antarctic ice sheets, or permanent changes to ocean currents due to warming. To the extent that these have a reasonable basis in science, don’t they create urgency around stopping global warming?

Another area of climate science that Koonin dismisses is “attribution studies”—the attempt to assess how much of a role human-caused climate change plays in extreme weather events. I have already mentioned Koonin’s skepticism around climate models, and he assumes that since climate models have flaws, attribution studies (which are based in part on those models) are equally flawed. It seems to me, however, that attribution centered on a specific weather event is a much simpler problem that modeling the climate as a whole. A previous blog post reviews a book on this topic.  

A final aspect of the science that Koonin doesn’t discuss is how to assess multiple weak lines of evidence that all point in the same direction. Koonin stresses the uncertainty around many different lines of evidence reported by the IPCC and others, and that makes sense. But although each is somewhat uncertain on its own, isn’t it appropriate to look at the overall picture that they paint?

Action is urgently needed. What troubles me most is Koonin’s conclusion: that we should wait for better science before deciding that eliminating greenhouse-gas emissions is necessary, and that meanwhile we should prepare to adapt to a warming world.

Here, we are getting into an area of personal opinion, not hard science. Koonin looks at the evidence and does not see that action on greenhouse gases is urgently needed. He also views reducing emissions to net zero as impractical. I look at the same evidence and feel a strong sense of urgency. I feel that we must get to net zero, even though I recognize that it will be very difficult and some of the necessary technology and infrastructure is still being developed.

As for the main theme of the book—the lack of public knowledge about the uncertainties in climate science—I do not see that as a critical issue. There are corresponding uncertainties in many other important areas of science, and people are often unaware of them. To that extent, we’re all forming opinions based on partial information, and some of it will turn out to be wrong. In an ideal world, we would act only when we have good information based on a solid scientific understanding of the processes involved.

In the real world, we don’t have that luxury. We have to act based on the information we have now, flawed though it may turn out to be. To me, the information we now have is enough to require urgent action. If we wait, it may be too late to make a difference.

Some other climate books that might interest you:

We can solve the climate crisis if we act now. Six new books tell how and provide lessons for Kendal.