Despite the modern advances of central air and cooling centers, record-hot weather still regularly kills people all over the world. A 2010 heat wave in Russia was blamed for killing about 55,000 people. An earlier one, in 2003, claimed 70,000 across Europe. And an infamously scorching stretch of the summer of 1995 in Chicago killed about 750.
Climate change brings with it the threat that such natural disasters could happen more often, with higher death tolls, as late spring and early fall start to feel more like summer, and as summer itself gets worse. Cities are particularly vulnerable, given the urban heat island effect (we also know that certain neighborhoods within most cities are at particularly grave risk). Temperatures around New York City, for example, increased by about 2 degrees Celsius between 1901 and 2000 – a rate that was higher than the national average.
Exactly how bad the heat waves will get will depend on some uncertain factors, like how fast global populations rise and how successful we are at curbing greenhouse gasses. But researchers at Columbia University's Earth Institute and the Mailman School of Public Health have at least attempted to come up with some estimates. In new research published in the journal Nature Climate Change, they downscale future temperature projections for the island of Manhattan using 16 climate models under two scenarios (one assumes rapid global population growth and scant attempts to limit emissions; the other assumes slower growth and technological advances that slow emissions by 2040).
In all 32 scenarios, compared to a baseline set in the 1980s, heat-related deaths in Manhattan go up, in some cases by as much as 90 percent by the year 2080. And these projections take into account that there will be fewer cold-related deaths from climate change. The net effect, though, still looks gruesome.
The biggest jump in deaths, these models suggest, will come from "the months surrounding summer," those stretches of May and September that we seldom associate today with heat waves. The chart at left, from the paper, shows the percent change in heat-related deaths, averaged across 16 models, in the 2080s relative to the 1980s. All of those summertime deaths also clearly wipe out any any positive changes in the wintertime death toll.
The reality in the future may be even worse than these researchers are projecting. This study doesn't take into account changes in demographics, and New York City (along with the rest of the country) will age in the coming decades. The study also doesn't consider how air quality may worsen with climate change.
But then again, we never know what technology (and health care) may bring us in the next 70 years. These early projections, though, should be enough to get us thinking now about how to get ready.