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

TLDR

Climate strongly influences global wildfire activity, and recent surges may signal fire weather–induced pyrogeographic shifts that, if coupled with ignition sources and available fuel, could markedly impact global ecosystems, societies, economies, and climate. The study develops a simple annual metric of fire weather season length using three daily global climate datasets and three fire danger indices, and maps its spatio‑temporal trends from 1979 to 2013. The authors combine the three daily global climate datasets with the three fire danger indices to compute an annual fire weather season length metric and map its spatio‑temporal evolution. Fire weather seasons have lengthened across 29.6 million km² (25.3 %) of vegetated Earth, raising the global mean season length by 18.7 %; burnable area affected by long seasons doubled (108.1 % increase), and the frequency of long seasons rose across 62.4 million km² (53.4 %) during the study’s second half.

Abstract

Abstract Climate strongly influences global wildfire activity, and recent wildfire surges may signal fire weather-induced pyrogeographic shifts. Here we use three daily global climate data sets and three fire danger indices to develop a simple annual metric of fire weather season length, and map spatio-temporal trends from 1979 to 2013. We show that fire weather seasons have lengthened across 29.6 million km 2 (25.3%) of the Earth’s vegetated surface, resulting in an 18.7% increase in global mean fire weather season length. We also show a doubling (108.1% increase) of global burnable area affected by long fire weather seasons (>1.0 σ above the historical mean) and an increased global frequency of long fire weather seasons across 62.4 million km 2 (53.4%) during the second half of the study period. If these fire weather changes are coupled with ignition sources and available fuel, they could markedly impact global ecosystems, societies, economies and climate.