Many of us realize climate change is a threat to our well being. But what we have not yet grasped is that the devastation wreaked by climate change is often just as much about headline-grabbing catastrophes as it is about the subtler accumulation of innumerable slow and unequal burns that are already underway — the nearly invisible costs that may not raise the same alarm but that, in their pervasiveness and inequality, may be much more harmful than commonly realized. Recognizing these hidden costs will be essential as we prepare ourselves for the warming that we have ahead of us.
Responsibility for mitigating climate change on the local level lies in part with public institutions — not only in encouraging emissions reductions, but also in facilitating adaptation. Public discourse around climate change too often misses the central role that local institutions play in this latter function, how much of the realized pain locally depends not simply on the physical phenomena of climate change per se but also how they interact with human systems — economic, educational, legal and political.
Let’s start with heat, which is killing more people than most other natural disasters combined. Research shows that record-breaking heat waves are only part of the story. Instead, it may be the far more numerous unremarkably hot days that cause the bulk of societal destruction, including through their complex and often unnoticed effects on human health and productivity. In the United States, even moderately elevated temperatures — days in the 80s or 90s — are responsible for just as many excess deaths as the record triple-digit heat waves, if not more, according to my calculations based on a recent analysis of Medicare records.
In some highly exposed and physically demanding industries, like mining, a day in the 90s can increase injury risk by over 65 percent relative to a day in the 60s. While some of these incidents involve clear cases of heat illness, my colleagues and I have found that a vast majority appear to come from ostensibly unrelated accidents, like a construction worker falling off a ladder, or a manufacturing worker mishandling hazardous machinery. In California, our research shows that heat may have routinely caused 20,000 workplace injuries per year, only a tiny fraction of which were officially recorded as heat-related.
A growing body of literature links temperature to cognitive performance and decision-making. Research shows that hotter days lead to more mistakes, including among professional athletes; more local crime; and more violence in prisons, according to working papers. They also correspond with more use of profanity on social media, suggesting that even an incrementally hotter world is likely to be a nontrivially more irritable, error-prone and conflictual one.
Children are not immune. In research using over four million student test scores from New York City, I found that, from 1999 to 2011, students who took their high school Regents exams on a 90-degree day were 10 percent less likely to pass their subjects relative to a day in the 60s. In other research, my colleagues Joshua Goodman, Michael Hurwitz, Jonathan Smith and I found that across the country, hotter school years led to slower gains on standardized exams like the Preliminary SAT exams. It may not seem a huge effect on average: roughly 1 percent of learning lost per one-degree-hotter school year temperatures. Probably hardly noticeable in any given year. But because these learning effects are cumulative, they may have significant consequences.
