2°C or 1,5°C: Why half a degree matters

27.04.2016 - Climate change impacts differ substantially for the two temperature limits included in the Paris agreement, a team of European researchers found. Published in the journal Earth System Dynamics, the analysis considers 11 different indicators including extreme weather events, water availability, crop yields, coral reef degradation and sea-level rise for a global warming of 1,5°C and 2°C by the end of the century. The additional half degree would mean a 10-cm-higher global sea-level rise by 2100, longer heat waves, and would result in virtually all tropical coral reefs being at risk, the researchers found.
2°C or 1,5°C: Why half a degree matters
Tropical coral reefs are at risk - half a degree could make the difference. Photo: NOAA

“We found significant differences for all the impacts we considered,” says lead author Carl Schleussner of Climate Analytics and the Potsdam Institute for Climate Impact Research (PIK). The team of 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. However, tropical regions and mostly developing countries would bear the brunt of the impacts of half a degree difference in global temperature.

 “Some researchers have argued that there is little difference in climate change impacts between 1.5°C and 2°C,” says Co-author Jacob Schewe of PIK. “Indeed, it is necessary to account for natural variability, model uncertainties, and other factors that can obscure the picture. We did that in our study, and by focusing on key indicators at the regional level, we clearly show that there are significant differences in impacts between 1.5°C and 2°C.”

Article: Schleussner, C.-F., Lissner, T. K., Fischer, E. M., Wohland, J., Perrette, M., Golly, A., Rogelj, J., Childers, K., Schewe, J., Frieler, K., Mengel, M., Hare, W., and Schaeffer, M. (2016): Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C, Earth Syst. Dynam., 7, 327-351, [doi:10.5194/esd-7-327-2016]

Weblink to the article: http://www.earth-syst-dynam.net/7/327/2016/


Weblink to the Press Release of the European Geosciences Union:

Weblink to the press briefing on "Historical responsibilities and climate impacts of the Paris agreement": http://client.cntv.at/egu2016/press-conference-8