Historical and future anthropogenic warming effects on the year 2015 droughts, fires and fire emissions of CO2 and PM2.5 in equatorial Asia.

In 2015, El Niño caused severe droughts in equatorial Asia (EA). The severe droughts enhanced fire activities in the dry seasons, leading to massive fire emissions of CO2 and aerosols. Using large event attribution ensembles of the MIROC5 atmospheric global climate model, we suggest that historical anthropogenic warming increased the chances of meteorological droughts exceeding the 2015 observations in the EA area. Large probability increases in stronger droughts than the 2015 event are found in the ensemble simulations of 1.5 °C and 2.0 °C global warming according to the Paris Agreement goals. Further drying is projected in the 3.0 °C ensemble. We combine these experiments and empirical functions between precipitation, burned area, and fire emissions of CO2 and PM2.5. Increases in the chances of the burned area and the emissions of CO2 and PM2.5 exceeding the 2015 observations due to anthropogenic climate change in the past are not significant. In contrast, there are significant increases in the burned area and CO2 and PM2.5 emissions even if the 1.5 °C and 2.0 °C goals are achieved. If global warming reaches 3.0 °C, as is expected from the current mitigation policies of nations, the chances of the burned area, CO2 and PM2.5 emissions exceeding the 2015 observed values become approximately 100 %, at least in the single model ensembles. We also compare changes in fire CO2 emissions due to climate changes and the land-use CO2 emission scenarios of five shared socio-economic pathways, where the climate change effects on fire are not considered. There are two main implications. First, in a national policy context, future EA climate policy will need to consider these climate change effects regarding both mitigation and adaptation aspects. Second, the consideration of fire increases would change global CO2 emissions and the mitigation strategy, which suggests that future climate change mitigation studies should take these factors into account. [ABSTRACT FROM AUTHOR]