Within a few decades even the coldest years will be warm by historical standards. After 2047, the mean air temperature worldwide will exceed even the highest annual temperature from 1860 to 2005 if countries continue to emit carbon dioxide at the rates they do now. That “new abnormal” will begin even sooner than 2047 in certain locations, with the earliest occurrences (dark red) being across the tropics. That is precisely where species are least able to adapt to even small variations “because they are so used to a constant climate,” says Camilo Mora of the University of Hawaii at Manoa, who led the study. Many biodiversity hotspots (yellow)—the places richest in species—lie in the tropics, so temperature rise could threaten a large number of land and ocean animals as soon as the late 2020s.
SCIENTIFIC AMERICAN ONLINE
Specific hotspots for birds, fishes and other taxa can be seen at ScientificAmerican.com/aug2014/graphic-science