Projected Changes in the Energy Release Component Under Climate Change in Northwest Predictive Services Areas

Résumé du livre

Fire management agencies in the United States (US) use fire danger indices from National Fire Danger Rating Systems as decision-support tools. A widely used index tracking seasonal dryness in the western US is the Energy Release Component (ERC). Historically, ERC percentile thresholds provide information on the potential for large and uncontrollable fires, but climate change may alter the utility of specific percentiles in identifying large fire potential in the future. We investigated two management-focused questions: 1) how has seasonal ERC and percentile values changed, and 2) how will ERC and the number of high fire danger days change under projected future climatic conditions. We calculated historical and future ERC for Predictive Service Areas in Oregon and Washington using station observations and downscaled climate models, respectively. ERC and frequency of high fire danger days during the fire season increased for most PSAs over the 1981-2010 period. These increases were consistent with projected increases in ERC and high fire danger days using climate projections, with the most acute increases projected east of the Cascades and during the peak of the fire season. Irrespective of changes in vegetation and fire management, these changes in fire danger have and will continue to increase wildfire exposure across the region.