As important as the Westerling et al. report is (see 2 previous posts), it is weak in clarifying the implications of the report for policy.
First, some background. Discussion of fire activity usually focuses on land-use history, and particularly on the legacy of fire suppression. That is, in some western forests, eighty years of suppressing wildfires has produced denser forest growth with more closed canopies and shifts in the predominant tree species. Before the 20th century, some of these forests experienced natural (or intentionally set) fires every ten years or less. Frequent fires produced an open, park-like forest that supported grass fires which didn't kill most mature trees. Dense, closed-canopy forests with heavy litter, on the other hand, burn dramatically and unpredictably. Some forests, especially in the subalpine regions of the Rocky Mountains, are naturally dense and have supported severe fire regimes for centuries.
Westerling et al. conclude that the largest fires—and the greatest rise in wildfires—in the past three decades have mostly occurred in such naturally dense sub-alpine forests. These fires are apparently correlated with changes in hydroclimate, but they are in forests which are relatively unaffected by land use history and by the legacy of fire suppression.
But this is not surprising. Unlike Ponderosa pine forests of the Southwest and California, subalpine Rocky Mt. forests do burn big, when they burn. So, it is not surprising that if there is an increase in fire size, it would be in those areas. And it is also well-accepted that past large fire events in these areas have been associated with drought.
It is not clear what the authors hope to gain by playing the two causes of increased fire activity (climate change and land-use history) off of one another. They demonstrate a relationship between large fires in subalpine forests and climate change that is more significant than we had previously recognized. But this does nothing to diminish the importance of the causal role of land-use history in areas of the Southwest and West Coast where the impacts of grazing, timbering, and fire suppression are more profound.
Although some careful distinctions are made in the body of the report, there are also generalized, misleading statements. The authors imply that forest restoration and fuels treatments will be “ineffective.” A more contextual stance is required for three reasons:
1.) Advocates of forest restoration do not hold that a return to pre-(Euro-)settlement forest structure is a panacea, nor that restoration should be used to alter natural fire regimes. If the climate-caused increase in wildfires is seen in regions with natural stand-replacement fire regimes, then there is no conflict with the policy of restorationists to use fuel treatment and prescribed burning where appropriate in order to reproduce the forest structure of understory fire regimes.
2.) Some advocates of fuels treatments are concerned exclusively with using cutting and burning techniques and silviculture to restore altered fire regimes (especially in Ponderosa pine forests). Others have advocated more radical and expensive measures with the primary goal of limiting the spread of massive wildfires. This latter position should be distinguished from a restorationist approach because it advocates changing historical fire regimes. The real debate in this case is over feasibility: can preventive tactics control fire spread in subalpine forests, and would they be more cost-effective than current firefighting techniques? This is a policy question. It does not hang off of discovering the cause of wildfire activity. Such radical fuel treatments may actually be more necessary in the face of increased fire activity, especially since large fires feed global warming significantly. Whether fuels treatments are “ineffective” has not been analyzed one way or the other by this research.
3.) The authors motivate concern about wildfires by referring to the hundreds of homes that are burned annually. This raises yet another policy issue, and one that is again unrelated to the substance of the paper. Implying an association between an increase in large fires and the loss of homes is disingenuous because most of such damage occurs at the urban-wildland interface, and mostly in California. Areas such as the recent fires in San Diego and in Texas and Oklahoma are not the primary concern of this report, which focuses on subalpine areas like those in sparsely populated Idaho and Montana.
The authors have tried to draw implications for policy. Unlike their scientific reasoning, their expression of policy implications is muddled and misleading. Why indulge in such rhetoric? Especially since substantive statements about the urgency of controlling global warming are conspicuously absent. Global warming is the real issue here, not fire policy. Perhaps this shift in rhetorical emphasis away from the real implications of the study should not be surprising, given the political environment.