Via The Guardian: Study reveals greater climate impacts of 2C temperature rise. Excerpt:
A difference of half a degree centigrade may be barely noticeable day to day, but the difference between 1.5C and 2C of global warming is a shift into a new, more dangerous climate regime, according to the first comprehensive analysis of the issue.
The scientists found the additional 0.5C would lead to longer heatwaves, greater droughts and, in the tropics, reduced crop yield and all coral reefs being put in grave danger.
The global climate change deal agreed in Paris in December pledged to “hold the increase in the global average temperature to well below 2C above pre-industrial levels and pursue efforts to limit the temperature increase to 1.5C.” Vulnerable countries, such as low-lying islands, have warned that 2C of climate change would wipe their nations from the map.
Understanding the different impacts from 1.5C or 2C of warming has been made more urgent by the recent run of record temperatures, with 2014 and 2015 breaking long-term records and recent months smashing previous highs. In February, the global temperature was 1.34C above the average from 1951-1980, according to Nasa data.
The new research was published in the journal Earth System Dynamics, and lead author Carl Schleussner, a scientific adviser at Climate Analytics in Germany, said: “We analysed the climate models used by the Intergovernmental Panel on Climate Change [and] considered 11 different indicators including extreme weather events, water availability, crop yields, coral reef degradation and sea-level rise. We found significant differences [between 1.5C and 2C] for all the impacts we considered.”
The researchers found: “For heat-related extremes, the additional 0.5C marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions.”
The analysis found that regional dry spells increased by 7% with 1.5C of warming but by 11% with 2C, while sea level rises by 10cm more in the hotter scenario. Some regions would be more affected than others with, for example, water availability in the Mediterranean falling by 9% under 1.5C of warming but 17% under 2C.
The research found crop yields might rise in some high-latitude regions, but “tropical regions like west Africa, south-east Asia, as well as central and northern South America are projected to face substantial local yield reductions, particularly for wheat and maize.”