Oren Cass argues that the worrying predictions of mainstream climate science are overblown (“The Problem With Climate Catastrophizing,” March 21). But rather than assessing the legitimate range of views regarding climate change, Cass marshals a series of fallacies in an apparent effort to justify a fossil fuel-friendly agenda of inaction.  

The clearest signs of trouble in Cass’ essay are rhetorical. By referring to mainstream climate scientists as “catastrophists,” Cass suggests that he is more interested in scoring political points than in engaging with the science surrounding climate change. It is true that the projected effects of unmitigated warming might objectively be characterized as catastrophic. If anything, however, scientists have been overly conservative in their assessments, tending to understate the actual threat posed by climate change—the very opposite of catastrophism. What’s more, the label creates a straw man: in Cass’ argument, “the catastrophist” is an amalgamation of perspectives set up for the purpose of being knocked down.

Cass’ suggestion that advocates who worry about future generations and choose to have children are hypocrites is another red flag. His singling out of Dave Bry, Travis Rieder, and Eric Holthaus is an ad hominem argument, and what's more, it often fails at a mathematical level. After all, when couples elect to have a single child, it leads to a decreasing population. Cass also misses the larger point: what most advocates for climate action seek is a way for their descendants to live on this planet sustainably.   

Cass correctly cites a quote I gave to Esquire in 2015 to describe the uncertainty surrounding the speed with which the Greenland Ice Sheet will melt. But this is where the usefulness of his characterization of mainstream climate science ends, since he proceeds to dismiss ice-sheet collapse and the other legitimate concerns of climate scientists as exaggerated. “Perhaps,” Cass notes, the dire risks that climate scientists foresee will materialize. But people shouldn’t take scientists’ predictions too seriously, he suggests, because “if nothing else, they are unfalsifiable.” This is an empty tautology. Predictions can never be “falsifiable” in the present: we must ultimately wait to see whether they come true.

The uncertainty that Cass cites as a reason for calm about climate change actually cuts both ways.

When it comes to making predictions about climate change, however, the sober reality is that the scientific community’s record has been strong. Consider, for example, the climate scientist James Hansen’s 1988 predictions about the warming that would result from increases in greenhouse-gas emissions over the decades that followed. The globe has continued to warm at about 0.2 degrees Celsius per decade (a rate of two degrees per century), as Hansen predicted. The melting of glaciers and sea ice, the warming of the oceans, and the rise in sea level have met or exceeded predictions made decades ago.

As scientists have improved the models, in fact, the predictions have often become more worrying. In 2013, the Intergovernmental Panel on Climate Change estimated that ice loss from the West Antarctic Ice Sheet would raise sea levels by up to three feet by 2100. The latest studies now project double that rise, thanks in part to scientists’ greater understanding of the physics of ice sheets. Indeed, the best available science suggests that the West Antarctic Ice Sheet is already losing ice, decades ahead of what climate models had predicted in the past.

This example points to a fatal flaw in Cass’ argument. The uncertainty that he cites as a reason for calm about climate change actually cuts both ways. When it comes to ice sheet collapse, uncertainty is working against us, exposing grave risks in humanity’s future. This is what scholars term the “fat tail” of climate risk, and it has clear implications for how governments, businesses, and individuals should deal with climate change. As the Harvard economist Martin Weitzman has argued, the possibility that the damage caused by climate change will be far greater than scientists currently estimate is a reason for tougher action. The world should hedge against extreme levels of risk by cutting greenhouse-gas emissions now.

In this context, reducing global carbon emissions should be understood as an extremely well-advised planetary insurance policy. Indeed, Americans take out fire insurance on their homes for levels of risk that pale in comparison to those associated with dangerous and irreversible climate change.

Flooding in Staten Island, New York, after Hurricane Sandy, November 2012.
Lucas Jackson / REUTERS


Consider next Cass’ characterization of climate risk. “A climate change worst-case scenario,” he writes, “differs from others in its speed. Although genuinely existential threats to civilization might circle the globe in months, days, or even minutes, total climate catastrophe unfolds over decades or centuries.”

Cass raises this apparent distinction to suggest that risks such as nuclear war or pandemic disease should be higher priorities for policymakers than climate change, since climate change plays out over a longer timeframe. But there is no reason why the world should not try to deal with climate change and other dangers simultaneously, regardless of the speed or likelihood with which those other dangers might materialize. To argue otherwise is to formalize the silly notion that one cannot walk and chew gum at the same time.

In any case, the effects of climate change are neither subtle nor far off: they are causing damage in the present. According to some estimates, climate change is already costing the global economy more than one trillion dollars each year. More broadly, the fact that inaction on climate change costs far more than action does betrays Cass’ claim that economic growth will more than compensate for the harms of environmental damage.

The effects of climate change are neither subtle nor far off.

Those harms are many. There is a rapidly growing body of scientific literature showing clear connections between climate change and damaging extreme weather events, such as Hurricane Sandy-like superstorms and unprecedented droughts like the one that recently struck California. Last month, five coauthors and I published an article demonstrating an additional linkage between climate change and a variety of recent extreme weather events. We showed that climate change is altering the jet stream in a way that favors persistent weather extremes, such as the heat wave and drought that hit Texas and Oklahoma in 2011 and the wildfires that affected California in 2015.

To make matters worse, Cass seriously downplays the fact that climate change exacerbates other problems, acting as what security experts call a threat multiplier. Because climate change increases the stress on food, water, and habitable land, it is intensifying competition for those resources among the world’s growing population. This is a recipe for more conflict, and it’s why U.S. military officials have declared climate change one of the greatest security threats that the United States will face in the decades ahead. Syria’s civil war—and the terrorist groups, such as ISIS, that have thrived in the chaos it has produced—has, among its root causes, an unprecedented drought that climate change almost certainly worsened.

Workers in an industrial zone in Surat, India, November 2009.
Arko Datta / REUTERS


Cass dismisses some scientists’ concerns about climate change as instances of “motivated reasoning.” But science represents the opposite of that process: as the physicist and science communicator Neil deGrasse Tyson has put it, science is true whether or not you believe in it.”

What is clear is that motivated reasoning has shaped the attitudes of those who have rejected or obscured the science of climate change, often when its implications threaten their bottom lines. James Inhofe, a U.S. senator who has called climate change a hoax and has received campaign funding from fossil-fuel companies, provided an unusually candid example of motivated reasoning in 2012. “I thought it must be true,” Inhofe told MSNBC in an interview about climate change, “until I found out what it cost.” The demands of responding to climate change, in other words, led Inhofe to reject the problem’s existence. Cass’ organization, the Manhattan Institute, has historically been funded by foundations associated with the billionaires Charles and David Koch, who have large holdings in the oil sector and advocate against regulations aimed at reducing carbon emissions.  

Cass’ essay closes with an attempt to draw a link between the work of biologist Paul Ehrlich, who in 1968 predicted that unchecked population growth and consumption would lead to mass starvation, and that of today’s climate scientists, who argue that unchecked carbon emissions will devastate the global environment. “Ehrlich was…wrong in 1968,” Cass writes, “for the same reasons his intellectual heirs are likely wrong about climate change today”—namely, thanks to an apparent eagerness to forecast doom. What’s more, Cass argues, today’s climate scientists have failed to reckon with the reasons, such as agricultural innovation, for which Ehrlich’s predictions have not yet materialized. To illustrate that point, he cites the Harvard environmental scientist Daniel Schrag (a friend of mine), who said in 2013 that “Ehrlich wasn’t wrong in ’68; he’s just wrong today.” But Schrag has acknowledged the extent to which technological innovation has so far prevented Ehrlich’s predictions from materializing. He was pointing out that the only thing Ehrlich got wrong was the timeframe during which his predictions would play out, and that the connections Ehrlich identified between unhindered consumption and environmental damage still hold. Schrag was right to do so. As I noted in my book The Hockey Stick and the Climate Wars:

Ehrlich’s early warning has ultimately proven prophetic. In the 1990s, a group of more than fifteen hundred of the world’s leading scientists, including half of the living Nobel Prize winners at the time, concluded that “Human beings and the natural world are on a collision course,” inflicting “harsh and often irreversible damage on the environment and on critical resources.” The major national academies of the world have issued similar joint statements.

There is a valuable debate to be had about how to address human-caused climate change. But the fact that the problem exists—and that it is a serious one—is no longer worth debating.

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