Global Emergence of Anthropogenic Climate Change in Fire Weather Indices

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.

Fine‐scale fire patterns mediate forest structure in frequent‐fire ecosystems

“…Forest restoration through the use of fire is an important management tool given the reality that mechanical treatments alone cannot achieve forest restoration goals across the vast areas in need of treatment (North et al 2012, 2015, Schoennagel et al 2017). Although our results indicate several ways in which managers can utilize low to moderate severity fire to maintain and create forest structures and pattern‐process relationships that mimic historical conditions, more extreme burning conditions, which are expected to increase under a changing climate (Abatzoglou et al 2019), may significantly reduce the likelihood that isolated trees and small tree groups survive future fires and can act as refugia.…”

Fire as a fundamental ecological process: Research advances and frontiers

“…An example is in the western United States, where the fire‐season length has increased by 34% (from 166 to 222 days), ultimately leading to increased annual area burned (Westerling, 2016). Globally, anthropogenic climate change has emerged as a significant driver of increased fire danger, independent of natural climate variability (Abatzoglou, Williams, & Barbero, 2019). These factors have relevance to ecological interactions as humans introduce and remove fire from landscapes (Moritz et al., 2014).…”

Attributing Increases in Fire Weather to Anthropogenic Climate Change Over France

“…Climate change projections suggest widespread increase in fire danger and fire weather extremes across much of the globe over the twenty-first century (Abatzoglou et al, 2019). These trends are already evident globally in the observational record (Jolly et al, 2015), including across parts of France (Dupire et al, 2017;Fréjaville and Curt, 2017;Curt and Fréjaville, 2018).…”

“…Additional challenges arise when attributing long-term changes in a multivariable phenomenon such as fire weather conditions (Abatzoglou et al, 2019). Fire weather indices integrate variables such as maximum temperature, precipitation, minimum relative humidity, and wind speed (Van Wagner, 1987) and the response to each of these inputs is often non-linear.…”

“…Fire weather indices can thus reflect the combined influence of weather and climate extremes occurring simultaneously, such as a prolonged drought period intersecting with a heatwave (Barbero et al, 2015). Some of these inputs may be strongly influenced by anthropogenic climate forcing, some not influenced at all, and some changes may offset one another (Flannigan et al, 2016;Abatzoglou et al, 2019). In this regard, the confluence of the background warming trend with dry years across Mediterranean regions is thought to have altered the likelihood of such compound events, as seen during 2003.…”