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SOURCE: Cosmos

DATE: August 7, 2019

SNIP: Two months ago, climate scientists studying US cities found that global warming could produce killer heat waves causing thousands of excess deaths during unusually hot summers like the one now affecting the eastern US and much of Europe.

Now, researchers have found that China faces an even worse problem – not just a few thousand extra deaths in unusually hot summers, but tens of thousands of additional deaths each year. And the problem, they say, will kick in at much lower rates of global warming than those predicted to endanger US cities.

Part of the problem, write Yanjun Wang of Nanjing University of Information Science & Technology and colleagues, in the journal Nature Communications, is that temperatures in China have been increasing faster than the global average.

But it isn’t the rise in average temperature that is the true problem, Wang’s team writes, so much as the fact that this rise is accompanied by an increase in the number of dangerously hot days.

In Chinese cities, they say, global warming of 1.5° degrees Celsius from pre-industrial levels (the Paris Agreement’s most ambitious not-to-exceed goal) could produce a 32.6% increase in the number of dangerously hot days.

An increase of 2.0 degrees (the Paris Agreement’s less-ambitious back-up goal) could produce a 45.8% increase.

Combining that with heat-fatality data from 27 large Chinese cities, the researchers calculated heat-death rates per year under each warming scenario, then extrapolated them to the rest of China’s 831 million city dwellers.

Their conclusion was that the difference between 1.5° degrees and 2.0° degrees matters – a lot. Even at 1.5° degrees, they found, China would experience a substantial increase in the number of annual deaths from heat. But at 2.0 degrees it would be substantially worse, with at least 27,900 extra deaths per year due simply to that extra 0.5 degree.