A UC Berkeley study published online this week in the journal Science purports to quantify the current harmful impacts of anthropogenic climate change. According to the study’s abstract, global warming already depresses U.S. corn yields by 48%, slows global economic growth by 0.25% annually, and elevates conflict risk in Africa by 11% compared to 1980.
A review article in Bloomberg lists several other troubling impacts supposedly brought to light by the Berkeley researchers, who applied “novel statistical approaches” to some 200 previous studies on how climate affects agriculture, labor productivity, human behavior, and health. Higher temperatures correlate with lower birth rates, an “uptick in profanity” (supposedly evidence of a decline in the “happiness index”), higher crime rates, and poorer scores on children’s math tests.
Further, as reported in ClimateWire ($), the researchers claim higher temperatures have increased U.S. energy consumption by 29%, U.S. sexual assault rates by 6%, and overall U.S. mortality by 11%.
A major conclusion of the study is that “current climatic conditions impose economic and social burdens on populations today that rival in magnitude the projected end-of-century impacts of climate change.” Translation: It’s worse than we thought!
No, it’s not. If the Berkeley study is correct, the horrors we have been told await us in 2100 unless the world unites to combat climate change are actually no big deal. The formerly future but now supposedly present impacts are either so minor in the scheme of things, or so confounded by the myriad other factors affecting social conditions, that we—or, at any rate, Berkeley researchers—would not even “observe” those harms without the aid of complex modeling and statistical manipulation.
The study is paywall protected, and so I have only read the “structured abstract” and have neither the time nor expertise to audit the 200 previous studies from which the Berkeley researchers draw their “data.” The following observations may nonetheless be pertinent.
Many factors far more important than gradual increases in average global temperature affect crime rates, children’s academic performance, sexual assaults, and the like. Only eggheads need computer models to know that during hot weather children learn better and employees are more productive if the school or work space is air conditioned.
The most important variable affecting economic conditions is economic policy, especially the presence or absence of economic liberty. The Heritage Foundation posts an Annual Index of Economic Freedom that allows you to monitor changes in ten different indicators (e.g. investment freedom, property rights, labor freedom) for every country in the world from 1995 to 2016. Did the Berkeley researchers include those data in their calculations? Doubtful!
U.S. energy consumption increased 21% from 1980 to 2015, but during the same period U.S. population grew by 43% and U.S. real GDP increased by 153%. Thus, despite any potential adverse climate change impact, U.S. per capita energy consumption decreased while the energy efficiency of the U.S. economy increased. Things are improving, not getting worse.
The Berkeley researchers claim U.S. corn yields would be 48% higher but for climate change. Guanter et al. (2014), a satellite imaging study published in Proceedings of the National Academy of Sciences, found that the U.S. corn belt has the highest gross primary production from photosynthesis of any region in the world, including the tropical rainforests. So if global average temperatures were just a little cooler, our corn belt would be almost half again more productive than it is now? Astonishing!
What we do know is that despite any potential adverse climate change impacts, U.S. corn yields have been increasing, decade-by-decade, since the 1960s. And despite projections that 2016 will be the warmest year in the instrumental record, U.S. farmers are on track to produce record amounts of corn and soybeans and Russia is expected to achieve its biggest grain harvest since the fall of the USSR.
As for the putative 11% increase in U.S. mortality, the U.S. age-adjusted risk of mortality dropped by 60% from 1930 to 2010—a period during which atmospheric carbon dioxide concentrations increased by 26.5%. Moreover, U.S. heat-related mortality rates have been declining, decade-by-decade, since the 1960s.
A final point. The Berkeley study is agenda-driven. Co-author Solomon Hsiang told ClimateWire the study shows climate change impacts are “like a tax.” In other words, “the study could provide a more robust foundation for designing policies, like pricing carbon dioxide emissions.”