Climate-induced variations in global wildfire danger from 1979-2013

Global wildfire activity is strongly linked to climate and recent surges in extreme fire events may signal global pyrogeographic changes in response to increased fire weather severity. Using three daily global climate datasets and three fire danger indices, we used these data to develop a simple metric of fire weather season length and we mapped spatial and temporal trends from 1979 to 2013. Here we show that fire weather seasons have lengthened across 27.8M km2 (23.8%) of the Earth's vegetated land surface, resulting in a 16.3% increase in global mean fire weather season length. We also show a near doubling (90.7%) of global burnable area affected by anomalously long fire weather seasons (>1.0 σ above historical mean) and an increased frequency of long fire weather seasons across 62.4M km2 (53.4%) of the globe's vegetated areas during the second half of the study period. If these fire weather changes are coupled with ignition source and available fuel, they could profoundly alter global pyrogeography and they may have pronounced global socio-economic, ecological and climate impacts.