Global Emergence of Anthropogenic Climate Change in Fire Weather Indices

TLDR

Global fire activity is driven by land‑cover change, policy, and climate, among other factors. The study aims to determine when fire weather changes, measured by the Fire Weather Index, become distinguishable from internal variability due to anthropogenic climate change. The authors use 17 climate models and the time‑of‑emergence framework to evaluate this. The analysis shows that anthropogenic increases in extreme Fire Weather Index days emerged over 22 % of burnable land by 2019, rising to 33–62 % by the mid‑21st century, with emergence expanding as global temperature rises and covering half the area at 2 °C versus 3 °C above preindustrial levels, underscoring the need for local adaptation to mitigate fire impacts.

Abstract

Abstract Changes in global fire activity are influenced by a multitude of factors including land‐cover change, policies, and climatic conditions. This study uses 17 climate models to evaluate when changes in fire weather, as realized through the Fire Weather Index, emerge from the expected range of internal variability due to anthropogenic climate change using the time of emergence framework. Anthropogenic increases in extreme Fire Weather Index days emerge for 22% of burnable land area globally by 2019, including much of the Mediterranean and the Amazon. By the midtwenty‐first century, emergence among the different Fire Weather Index metrics occurs for 33–62% of burnable lands. Emergence of heightened fire weather becomes more widespread as a function of global temperature change. At 2 °C above preindustrial levels, the area of emergence is half that for 3 °C. These results highlight increases in fire weather conditions with human‐caused climate change and incentivize local adaptation efforts to limit detrimental fire impacts.