This article is an excerpt from the Shortform book guide to "Unsettled" by Steven E. Koonin. Shortform has the world's best summaries and analyses of books you should be reading.
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What are the projections for climate-related deaths? Will climate change crash the economy?
Climate activists have misled the public into thinking there’s proof that our actions have led to global warming and possible climate catastrophe, according to former energy industry scientist Steven E. Koonin. On the contrary, he argues, the facts about climate change are far from certain.
Continue reading to learn why Koonin believes that we’re not headed for a climate catastrophe.
Climate Catastrophe?
Koonin disputes predictions that climate change will lead to disaster in three areas: increased climate-related deaths, widespread food shortages, and economic turmoil. By appealing to the very models that some use to support dire predictions, Koonin argues that climate catastrophe is not in our future. Let’s take a look at the data in all three areas that Koonin uses to make his case.
Climate-Related Deaths
First, Koonin disputes economist Michael Greenstone’s projection that climate change will cause an additional 85 deaths per 100,000 people by 2100. On the contrary, he argues that Greenstone’s concern about climate-related deaths is overstated.
(Shortform note: Projections of climate-related deaths vary by model. For example, another influential 2021 study found that, under the baseline emissions scenario in which average temperature rises by 4.1°C, there will be 83 million excess deaths by 2100. This amounts to 4.6 million climate-related deaths annually in 2100, making climate change’s mortality rate comparable to those of obesity and air pollution.)
Koonin finds that, to make his projection, Greenstone’s model assumed the IPCC’s worst-case emissions scenario would occur, in which our carbon emissions triple and we’re responsible for 8.5 W/m2 of the energy in the climate system. However, Koonin notes that a recent analysis suggests that this scenario is unlikely because we’re projected to reduce our coal consumption by the end of the century.
Rather, under the more realistic assumption that we’ll be responsible for 4.5 W/m2 of the climate system’s energy by 2100, he observes that Greenstone’s model predicts a climate-related death rate of 14 per 100,000 by 2100—one-sixth of his stated estimate. Hence, according to Greenstone’s own model, climate-related deaths by 2100 will be far fewer than reported.
(Shortform note: Current projections estimate that the world population in 2100 will total 11.2 billion people. Consequently, even if Koonin is correct that climate-related deaths will have a mortality rate of 14 per 100,000 by 2100, that still means that over 1.5 million people will die annually because of climate change by 2100.)
Widespread Food Shortages
Next, Koonin criticizes a 2019 New York Times article reporting that climate change has contributed to global food shortages, according to an IPCC report. In response, Koon argues that the IPCC’s report doesn’t justify claims of food shortages.
Koonin notes that the IPCC’s report itself found that calories per capita have actually increased by about one-third globally since 1961. Moreover, he observes that from 1961 to 2011, our global crop yields have increased dramatically—wheat, rice, and corn yields have more than doubled.
According to Koonin, the IPCC’s report makes a more modest claim than reported by The New York Times: Crops yields are slightly lower than they would have been, because of human-induced climate change. For example, although the wheat yield rose 100% from 1981 to 2010, the IPCC estimated that it would have risen 104% in the absence of human-caused climate change. So, the IPCC’s report only justifies the modest claim that climate change has had a slight impact on global food yields.
(Shortform note: Other recent studies have suggested that the agricultural impact of anthropogenic climate change is greater than the IPCC’s report suggested. For instance, a 2021 study found that, although agricultural research has led to rising crop yields, human-induced climate change has decreased total agricultural output by about 21% since 1961. In other words, anthropogenic climate change has lost an equivalent of seven years of agricultural growth since 1961.)
Economic Turmoil
Finally, Koonin casts doubt on the US’s 2018 National Climate Assessment (NCA), which reported that climate change would substantially harm the US economy by 2100, arguing that climate change will have a nearly undetectable effect on economic growth.
To show as much, he notes that, according to the IPCC’s 2014 report, AR5, the projected warming of 3°C by 2100 would cut the global economy by 3% by 2100, or 0.04% annually. Because the economy is otherwise projected to grow at a rate of 2%, Koonin predicts that climate change will instead slow that growth to 1.96%. In other words, climate change will have a nearly undetectable effect on economic growth.
(Shortform note: Koonin’s claim that climate change will have a negligible economic impact is arguably overstated. In False Alarm, Bjorn Lomborg considers the economic effects of climate change over the next 500 years, rather than the effects by 2100 alone. Using the Dynamic Integrated Climate-Economy Model (DICE), he finds that climate change will cost 3.6% of global GDP by 2500, or $140 trillion—over six times the US GDP in 2021. Thus, by focusing on the yearly economic growth rate rather than the total loss in GDP, Koonin obscures climate change’s actual economic impact.)
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Here's what you'll find in our full Unsettled summary:
- That humans are only partially to blame for the warming climate
- Why the proposed solutions to climate change are unlikely to succeed
- Alternative responses to climate change and how to improve understanding
