Abstract: |
Forest Service fire suppression expenditures are enormous. Expressed in constant 2002 dollars, annual expenditures from 1970 to 1999 averaged about $265 million. In FYs 2000, 2002, and 2003, FS suppression expenditures broke the billion-dollar mark, nearly four times the annual average. What is the primary causal factor of these increasing expenditures? Cost per acre (in constant dollars), though highly variable, has fallen and leveled off since the 1970s, indicating that cost per acre cannot be blamed for soaring expenditures. Forest Service suppression expenditures, however, are highly correlated with acres burned (r = 0.762 for the period 1971 - 2002), and there has been a dramatic shift in the number of acres burned since 1987. Pre-1987, annual acres burned averaged approximately 284,000. Since 1987, acres burned have averaged over a million.We estimate a statistical forecast model for wildfire area burned and suppression costs as a function of soil moisture anomalies available for the growth and wetting of fuels. Our forecast model is estimated on the USDA Forest Service’s fire history for the western United States for 1987-2000. Despite the fact that this model is estimated after the apparent shift in western fire regimes in the 1980s, it reproduces observed area burned for the preceding years of our record (1970 – 1986) with no reduction in skill. We take this as a strong indication that the greater severity and expense of recent fire seasons over what was experienced in the 1970s and early 1980s is due in large part to climatological factors captured by the Palmer Drought Severity Index (PDSI), our proxy for soil moisture. Based on our forecast models of wildfire area burned and suppression costs, we found a high probability that western wildfire suppression costs in 2003 would exceed the Forest Service’s budget allocation of US$300 million for wildfire suppression. |
