On climate science, the New York Times blows it

Bret Stephens is a right-wing journalist and climate-science denier who spent most of his career writing for the Wall Street Journal. He was hired as an opinion writer by the New York Times in early 2017, and wrote his first column on April 28.

I first learned about Mr. Stephens’s new job at the New York Times from a blog posting by Joe Romm, a physicist who writes extensively about climate science and energy economics. Romm pointed out an inconsistency between the current advertising campaign of the Times – “Truth. It’s more important now than ever” – and Stephens’s history of writing about climate change and other issues. The Times received more than 1500 comments and 550 letters to the editor about Stephens’s first column within 48 hours of its appearance on April 29. Romm, Susan Matthews, David Roberts, and others wrote thorough rebuttals of Stephens’s argument, such as it was. I won’t reiterate these rebuttals, but wish to make a few additional points about denial of climate science in Stephens’s New York times column.

Mr. Stephens claims to accept the fact that the average temperature on Earth has increased in the last 150 years due in part to human activity. This gives his column a patina of plausibility compared to the claims of others who deny climate science. But this apparent plausibility is really only a pretense. He ignores all of the other evidence of recent, rapid climate change – melting glaciers, shrinking ice caps on Greenland, decreased ice in the Arctic Ocean, melting permafrost, rising sea levels, more extreme weather events. He fails to acknowledge that our addition of greenhouse gases to the atmosphere is the primary cause of recent climate change.

Stephens’s biggest problem is with the mathematical models that are used to project future climate conditions under various scenarios. He incorrectly implies that climatologists claim certainty about these projections, and constructs an analogy between this purported certainty of climatologists and the supposed certainty of the Hillary Clinton presidential campaign that she would win the election last November. According to Stephens, the Clinton campaign was wrong, so the climatologists might also be wrong. This analogy is phony at several levels. The politicians weren’t as certain as Stephens implies. The climatologists include uncertainty in all of their model projections. And the climate models are based on detailed knowledge of atmospheric chemistry and physics, unlike the statistical models of polling data that politicians and the news media use, which depend on extrapolating from surveys of a small number of voters to the voting population as a whole. In addition, there are various ways of testing global climate models by comparing observed data to predictions of the models. The figure below shows one example illustrating that these models can account for measured average temperature of Earth’s surface between 1860 and 2000 only if models include both emission of greenhouse gases by burning fossil fuels and natural factors such as variation in solar radiation and volcanic activity.

Average annual temperature of Earth’s surface from 1860 to 2000 (red lines) compared to projections of three sets of global climate models: models with only natural forcings such as changes in solar radiation and sunspot activity (a), models with only anthropogenic forcings such as release of greenhouse gases into the atmosphere (b). and models with both natural and anthropogenic forcings (c). The gray bands show the range of projections for four models in case. The temperature anomaly shown on the vertical axes of these graphs is the deviation from the average temperature between 1880 and 1920 in degrees Celsius (multiply these values by 1.8 for degrees Fahrenheit). Projections shown in these graphs are hindcasts, tests of how well models fit existing data, rather than forecasts, or predictions of future data.

For Stephens, the uncertainty surrounding predictions of climate models appears to justify a wait-and-see approach to dealing with climate change. This ignores three fundamental principles of climate change that I discuss in my book “Tools for Critical Thinking in Biology”: inertia, positive feedback, and tipping points. About 20% of the carbon dioxide that we add to the atmosphere by burning fossil fuels today will remain in the atmosphere for 1000 years (inertia). Increased temperatures in the arctic cause less ice in the Arctic Ocean, making the surface darker, meaning more heat is absorbed, warming the arctic region further, melting more ice, and so forth (positive feedback). Finally, some effects of anthropogenic climate change may cause transitions to dramatically different conditions (tipping points) that will be irreversible fur hundreds of human generations. For example, sea level was 23 feet higher during the Eemian interglacial period that ended, 125,000 years ago, but temperature was only a fraction of 1oF higher than today. As global temperatures continue to increase in response to continued addition of greenhouse gases to the atmosphere, with arctic temperatures rising much faster than those at lower latitudes, we may reach a tipping point in which the Greenland ice cap melts, causing sea levels similar to those in the Eemian that will remain elevated for many generations. Inertia, positive feedback, and tipping points in the global climate mean that Stephens’s wait-and-see approach is indefensible.

Stephens seems to be fixated on trying to undermine the overwhelming consensus among climate scientists in the basic facts of climate change and the resulting projections of what we face if we continue business as usual in our use of fossil fuels. Contrary to his claim, this consensus doesn’t mean that the science is settled. Far from it: I’m not a climatologist, but climatology is one of the most active and exciting areas of research today, with new findings reported almost weekly (most of which should make us even more worried about the future).

The heroes of Stephens’s story are ordinary citizens, who may be “indifferent to … the prospect of planetary calamity”, but “have a right to be skeptical of an overweening scientism.” Stephens implies that climate scientists are often villains, but I see climate scientists who forge ahead with their research in the face of abuse from politicians beholden to fossil fuel interests as heroic. Ordinary citizens can also be heroic if they nurture their curiosity about science, develop real skepticism instead of the faux skepticism of science deniers, and above all demand honesty in themselves and others.

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