Yes, it’s getting hotter in the U.S. — but the humidity will kill you

http://grist.org/list/yes-its-getting-hotter-in-the-u-s-but-the-humidity-will-kill-you/

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It’s difficult to find a silver lining in our climate-changed future. Yes, the heat is expected to surpass unhealthy levels and get into lethal territory by the end of the century. And true, hotter temperatures mixed with humidity compounds the problem, making it extremely difficult for our bodies to regulate temperatures. On the other hand, according to Rutgers climatologist Robert Kopp, you will still have nearly an hour a day to engage in light outdoor physical activity in the shade before heat stroke sets in.

The recent Risky Business report on the economic impacts of climate change took a look at some of the physical repercussions of increasing heat and humidity. Sharon Begley at Reuters had this to say:

The body’s capacity to cool down in hot weather depends on the evaporation of sweat. That keeps skin temperature below 95 degrees Fahrenheit (35 Celsius). Above that, core temperature rises past 98.6F. But if humidity is also high, sweat cannot evaporate, and core temperature can increase until the person collapses from heat stroke. “If it’s humid you can’t sweat, and if you can’t sweat you can’t maintain core body temperature in the heat, and you die,” said Dr Al Sommer, dean emeritus of the Bloomberg School of Public Health at Johns Hopkins University and author of a chapter on health effects in the new report.

We know where the effects will be the worst, so we could just avoid those places, right?

The highest heat-plus-humidity reading in the United States was in 1995 in Appleton, Wisconsin, when the outside temperature was 101F. While the Upper Midwest is not known for tropical conditions, climate research shows that it will experience more warming than lower latitudes as well as more humidity. As a result, the deadliest heat-and-humidity combinations are expected to center around that region, with threads reaching to the Eastern Seaboard and islands of dangerous conditions along the northwest Pacific coast.