.5 C warming boosted extreme weather; impacts well outside bounds of natural variability

June 30, 2017  see full article at phys.org here

Half a degree Celsius [.5C] of global warming has been enough to increase heat waves and heavy rains in many regions of the planet, researchers reported Friday. Comparing two 20-year periods—1960-79 and 1991-2010—between which average jumped 0.5 C (0.9 F), scientists found that several kinds of extreme weather gained in duration and intensity.

The hottest summer temperatures increased by more than 1 C (1.8 F) across a quarter of Earth’s , while the coldest winter temperatures warmed by more then 2.5 C (4.5 F). The intensity of extreme precipitation grew nearly 10 percent across a quarter of all land masses, and the duration of hot spells—which can fuel devastating forest fires—lengthened by a week in half of land areas.

These changes were well outside the bounds of natural variability, according to the study, published in the journal Nature Climate Change….

….”With the warming the world has already experienced, we can see very clearly that a difference of 0.5 C really does matter,” said co-author Erich Fischer, a scientist at ETH Zurich in Switzerland. Earlier research based on computer models, also led by Schleussner, concluded that 2 C of would—compared to 1.5 C—double the severity of crop failures, water shortages and heatwaves in many regions of the world. It also found that holding the rise in temperature to 1.5 C would give coral reefs—the cornerstone of ecosystems that sustain half-a-billion people and a quarter of marine wildlife—a fighting chance of adapting to warmer and more acidic seas….

Carl-Friedrich Schleussner et al. In the observational record half a degree matters, Nature Climate Change (2017). DOI: 10.1038/nclimate3320