Future summers could be hotter than any on record

http://www.eurekalert.org/pub_releases/2016-06/nsf-fsc061316.php

Public Release: 13-Jun-2016
Future summers could be hotter than any on record
Reducing carbon emissions could cut risk of record-breaking summertime heat in half
National Science Foundation

In 50 years, summers across most of the globe could be hotter than any summer experienced by people to date, according to a study by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colo.

If climate change continues on its current trajectory, the probability that summers between 2061 and 2080 [45 to 64 years from now] will be warmer than the hottest on record stands at 80 percent across the world's land areas, excluding Antarctica, which was not studied. [So they will affect many people living today, and certainly their children and grandchildren.]

If greenhouse gas emissions are reduced, however, that probability drops to 41 percent.

"Extremely hot summers always pose a challenge to society," said NCAR scientist Flavio Lehner, lead author of the study. "They can increase the risk for health issues, and can also damage crops and deepen droughts. Such summers are a true test of our adaptability to rising temperatures."

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"Instead of just comparing the future to 95 summers from the past, the models give us the opportunity to create more than 1,400 possible past summers," Lehner said. "The result is a more comprehensive look at what should be considered natural variability and what can be attributed to climate change."

Emissions cuts could yield big benefits

The results show that between 2061 and 2080, summers in large parts of North and South America, central Europe, Asia, and Africa have a greater than 90 percent chance of being warmer than any summer in the historic record if emissions continue unabated.

That means virtually every summer would be as warm as the hottest to date.

In some regions, the likelihood of summers being warmer than any in the historical record remained less than 50 percent, but in those places -- including Alaska, the central U.S., Scandinavia, Siberia and continental Australia -- summer temperatures naturally vary greatly, making it more difficult to detect effects of climate change.

Reducing emissions would lower the global probability of future summers that are hotter than any in the past, but would not result in uniformly spread benefits. In some regions, including the U.S. East Coast and large parts of the tropics, the probability would remain above 90 percent, even if emissions were reduced.

But reduced emissions would result in a sizable boon for other regions of the world.

Parts of Brazil, central Europe, and eastern China would see a reduction of more than 50 percent in the chance that future summers would be hotter than the historic range. Since these areas are densely inhabited, a large part of the global population would benefit significantly from climate change mitigation.

"It's often overlooked that the majority of the world's population lives in regions that will see a comparably fast rise in temperatures," Lehner said.




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