In a recent commentary for Nature Medicine, the Georgetown University biologist Colin Carlson used a decades-old formula to calculate that warming had already killed four million people globally since 2000 just from malnutrition, floods, diarrhea, malaria and cardiovascular disease. As Carlson notes, this means that, since the turn of the millennium, deaths from climate change have already exceeded those from all World Health Organization global-health emergencies other than Covid-19 combined. “Vanishingly few of these deaths will have been recognized by the victims’ families, or acknowledged by national governments, as the consequence of climate change,” he says.
Going forward, most estimates suggest the impact should grow along with global temperature. According to one 2014 projection by the W.H.O., climate change is most likely to cause 250,000 deaths annually from 2030 to 2050. According to research by the Climate Impact Lab, a moderate emissions trajectory, most likely leading to about two degrees of warming by the end of the century, would produce by that time about 40 million additional deaths.
Other work is even more striking. In a recent paper published in The Proceedings of the National Academy of Sciences, a team led by Drew Shindell of Duke University calculated that heat exposure alone is already killing more than 100,000 Indians and about 150,000 Chinese each year. Not all of these deaths are attributable to warming — people died from heat exposure in the preindustrial past, of course — but the trends for all the examined countries were clear and concerning. By the end of the century, the team calculated, even in a low-emissions, low-warming scenario, annual mortality from heat exposure could reach 500,000 in India and 400,000 in China. This is just from heat, remember, and as Shindell points out, there are plenty of known climate impacts that are so hard to model that they are often simply not modeled. “There’s all kinds of stuff missing, and we still get big numbers,” Shindell says. “That should actually be scary.”
One thing that is almost always left out is air pollution. This is the research area for which Shindell is best known, and his most notorious finding on the subject is that simply burning the additional fossil fuel necessary to bring the planet from 1.5 degrees of warming up to two degrees would produce air pollution that would prematurely kill an estimated 153 million people.
If that number shocks you, consider that, according to the new paper, the present-day figures are more than two and a half million Chinese deaths each year, more than two million in India and about 200,000 annually in Pakistan, Bangladesh and the United States each. Even given rapid decarbonization, Shindell and his co-authors find that, by the end of the century, particulate pollution might be responsible for the annual premature deaths of four million Indians, two million Chinese, 800,000 Pakistanis, 500,000 Bangladeshis and 100,000 Americans.