Impact of climate change on the fire weather in Indian forests

Forest fires strongly depend on local weather conditions. Weather conditions conducive for occurrence and growth of fires is known as "fire weather". This work investigates how climate change can affect the future fire weather in Indian forests using the Canadian Forest Fire Danger Rating System (CFFDRS), a well-known fire risk assessment system. This model is driven by high-resolution daily data of fire-relevant meteorological variables like temperature, relative humidity, wind speed, and accumulated precipitation to compute the Fire Weather Index (FWI) as an indicator of fire danger for current (2006-2015) and end-century (2091-2100) periods over 5 Indian forest zones, viz., deciduous, Himalayan, Northeast, Thorn, and Western Ghats. The meteorological data is obtained by dynamically downscaling the CMIP5 climate projections from the CESM model to a 10 km grid. The baseline current period simulated FWI is calibrated and validated with the pixel-wise fire count data retrieved from MODIS active fire data.

The FWI projections indicate that FWI and its related metrics like Daily/Seasonal Severity Rating (DSR/SSR) show a consistent increase in most of the forest regions of the country. The pre-monsoon shows a notably high increase in the spatial SSR by the end century. Despite a moderate increase of about 5% in climatological FWI values, the days exceeding severe FWI are estimated to rise by an average of 30-40 days over some forest clusters. Our findings strongly suggest that by the end of the century, 3 out of 5 years could have longer and more severe fire seasons in some forest clusters. In particular, fire hazard is likely to strongly increase in the Cachar semi-evergreen and mixed moist deciduous forests in the Northeast, Chir pine and Sal forests in the Himalayan foothills, northern moist evergreen forests in the Western Ghats, and southern mixed deciduous forests in a few states in central India.

This study is one of the first attempts to quantify the effects of climate change on forest fire hazard in India. It can be a valuable asset for fire management organizations and policymakers for designing appropriate mitigating measures.