1.5 C vs 2 C global warming: New study shows why half a degree matters

http://www.eurekalert.org/pub_releases/2016-04/egu-1cv041816.php

Public Release: 21-Apr-2016
1.5 C vs 2 C global warming: New study shows why half a degree matters
European Geosciences Union

European researchers have found substantially different climate change impacts for a global warming of 1.5°C and 2°C by 2100, the two temperature limits included in the Paris climate agreement. The additional 0.5°C would mean a 10-cm [4 in.]-higher global sea-level rise by 2100, longer heat waves, and would result in virtually all tropical coral reefs being at risk.

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"We found significant differences for all the impacts we considered," says the study's lead author Carl Schleussner, a scientific advisor at Climate Analytics in Germany. "We analysed the climate models us

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We considered 11 different indicators including extreme weather events, water availability, crop yields, coral reef degradation and sea-level rise."

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The team, with researchers from Germany, Switzerland, Austria and the Netherlands, identified a number of hotspots around the globe where projected climate impacts at 2°C are significantly more severe than at 1.5°C. One of these is the Mediterranean region, which is already suffering from climate change-induced drying. With a global temperature increase of 1.5°C, the availability of fresh water in the region would be about 10% lower than in the late 20th century. In a 2°C world, the researchers project this reduction to double to about 20%.

In tropical regions, the half-a-degree difference in global temperature could have detrimental consequences for crop yields, particularly in Central America and West Africa. On average, local tropical maize and wheat yields would reduce twice as much at 2°C compared to a 1.5°C temperature increase.

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On a global scale, the researchers anticipate sea level to rise about 50 cm [20 in.] by 2100 in a 2°C warmer world, 10 cm [4 in.] more than for 1.5°C warming. "Sea level rise will slow down during the 21st century only under a 1.5°C scenario," explains Schleussner.

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