President Obama, er, slipped into hot water when The Atlantic reported that he frequently suggests to his staff that fear of terrorism is overblown, with Americans more likely to die from falls in tubs than from attacks by terrorists. The timing was awkward, coming right before the Brussels bombings, but Obama is roughly right on his facts: 464 people drowned in America in tubs, sometimes after falls, in 2013, while 17 were killed here by terrorists in 2014 (the most recent years for which I could get figures). Of course, that’s not an argument for relaxing vigilance, for at some point terrorists will graduate from explosives to nuclear, chemical or biological weapons that could be far more devastating than even 9/11. But it is an argument for addressing global challenges a little more rationally. The basic problem is this: The human brain evolved so that we systematically misjudge risks and how to respond to them. Our visceral fear of terrorism has repeatedly led us to adopt policies that are expensive and counterproductive, such as the invasion of Iraq. We have ramped up the intelligence community so much that there are now seven times as many Americans with security clearances (4.5 million) as live in Washington, D.C. Meanwhile, Donald Trump responded to the Brussels attacks with crowd-pleasing calls for torture or barring Muslims that even Republican security experts agree are preposterous. On the same day as the attacks, a paper by James E. Hansen and other climate experts was released arguing that carbon emissions are transforming our world far more quickly than expected, in ways that may inundate coastal cities and cause storms more horrendous than any in modern history. The response? A yawn. Hansen is an eminent former NASA scientist, but he’s also an outlier in his timing forecasts, and I’m not qualified to judge whether he’s correct. Yet whatever the disagreement about the timeline, there is scientific consensus that emissions on our watch are transforming our globe for 10,000 years to come. As an important analysis in Nature Climate Change put it, “The next few decades offer a brief window of opportunity to minimise large-scale and potentially catastrophic climate change that will extend longer than the entire history of human civilisation thus far.” To put it another way, this year’s election choices may shape coastlines 10,000 years from now. Donald Trump and Ted Cruz have both mocked the idea of human-caused climate change, with Trump suggesting that it is a hoax invented by China to harm the American economy (he now says that last point was a joke). The upshot is that Brussels survived this week’s terrorist attacks, but it may not survive climate change (much of the city is less than 100 feet above sea level). Doesn’t it seem prudent to invest in efforts to avert not only shoe bombers but also the drowning of the world’s low-lying countries? “We have a political system that engages quickly and powerfully in response to terrorism and security risks,” notes Daniel Esty, an environment expert at Yale Law School, “but doesn’t seem capable of galvanising action on climate change and other risks that are less visible and spread over time and space.” The reason seems to be — how do I put this politely? — that we evolved in ways that leave us irrational. When we spot a harmless garter snake, our brains light up with activity as we process the “threat.” That’s because as primate brains evolved over tens of millions of years, poisonous snakes were a threat that we are highly adapted to address, with special brain cells that are extremely sensitive to snake images. Unfortunately, our brains are not well adapted to most of the biggest threats we actually face in the 21st century. Warn us that climate change is destroying our planet, and only a small part of our prefrontal cortex (which worries about the future) will glimmer; then we’ll go back to worrying about snakes or their modern equivalent — terrorists. Daniel Gilbert, a professor of psychology at Harvard, says that the kind of threats that we evolved to deal with are those that are imminent rather than gradual, and those that involve a deliberate bad actor, especially one transgressing our moral code. Explaining our lack of concern for global warming, he noted, “Climate change is caused by the burning of fossil fuels, not flags.” In short, our brains are perfectly evolved for the Pleistocene, but are not as well suited for the risks we face today. If only climate change caused sharp increases in snake populations, then we’d be on top of the problem! Yet even if our brains sometimes mislead us, they also crown us with the capacity to recognise our flaws and rectify mistakes. So maybe we can adjust for our weaknesses in risk assessment — so that we confront the possible destruction of our planet as if it were every bit as ominous and urgent a threat as, say, a passing garter snake. (A version of this op-ed appeared in print in The New York Times on March 24, 2016). The writer is a New York Times columnist, and co-author of Half the Sky & A Path Appears