Jun 27, 2012

Satellite-based assessment of climate controls on US burned area

by
D. C. Morton, G. J. Collatz, D. Wang, J. T. Randerson, L. Giglio, and Y. Chen
,
Biogeosciences Discussions
  • Conducts the first national assessment of climate controls on US fire activity using two satellite-based estimates of monthly burned area (BA), the Global Fire Emissions Database (GFED, 1997–2010) and Monitoring Trends in Burn Severity (MTBS, 1984–2009) BA products
  • Analyzes the relationships between monthly BA and potential evaporation (PE) derived from reanalysis climate data at 0.5° resolution for each US National Climate Assessment (NCA) region
  • Finds that US fire activity increased over the past 25 yr, with statistically significant increases in MTBS BA for entire US and the Southeast and Southwest NCA regions
  • Finds that monthly PE was strongly correlated with US fire activity, yet the climate driver of PE varied regionally
  • Finds that fire season temperature and shortwave 15 radiation were the primary controls on PE and fire activity in the Alaska, while water deficit (precipitation – PE) was strongly correlated with fire activity in the Plains regions and Northwest US
  • Finds that BA and precipitation anomalies were negatively correlated in all regions, although fuel-limited ecosystems in the Southern Plains and Southwest exhibited positive correlations with longer lead times (6–12 months)
  • Finds that fire season PE increased from the 1980s–2000s, enhancing climate-driven fire risk in the southern and western US where PE-BA correlations were strongest
  • Finds that spatial and temporal patterns of increasing fire season PE and BA during the 1990s–2000s highlight the potential sensitivity of US fire activity to climate change in coming decades
  • Finds, however, that climate- fire relationships at the national scale are complex, based on the diversity of fire types, ecosystems, and ignition sources within each NCA region
  • Concludes that changes in the seasonality or magnitude of climate anomalies are therefore unlikely to result in uniform changes in US fire activity