Drylands face potential threat under 2 °C global warming target

The Paris Agreement aims to limit global mean surface warming to less than 2 degrees C relative to pre-industrial levels(1-3). However, we show this target is acceptable only for humid lands, whereas drylands will bear greaterwarming risks. Over the past century, surface warming over global drylands (1.2-1.3 degrees C) has been 20-40% higher than that over humid lands (0.8-1.0 degrees C), while anthropogenic CO2 emissions generated from drylands (similar to 230 Gt) have been only similar to 30% of those generated from humid lands (similar to 750 Gt). For the twenty-first century, warming of 3.2-4.0 degrees C (2.4-2.6 degrees C) over drylands (humid lands) could occur when global warming reaches 2.0 degrees C, indicating similar to 44% more warming over drylands than humid lands. Decreased maize yields and runoff, increased long-lasting drought and more favourable conditions for malaria transmission are greatest over drylands if global warming were to rise from 1.5 degrees C to 2.0 degrees C. Our analyses indicate that similar to 38% of theworld's population living in drylandswould suffer the effects of climate change due to emissions primarily from humid lands. If the 1.5 degrees C warming limit were attained, the mean warming over drylands could be within 3.0 degrees C; therefore it is necessary to keep globalwarming within 1.5 degrees C to prevent disastrous effects over drylands.