which is published as a chapter in the volume Wildfire Policy: Law and Economics Perspectives, Bradshaw and Lueck editors, 2012.
Jason is Henry L. and Grace Doherty Charitable Foundation Professor of Law Nicholas E. Chimicles Research Professor in Business Law and Regulation University of Virginia School of Law in Charlottesville Virginia. Jason’s scholarship has examined subjects ranging from natural resources law to torts and contracts.
Jonathan is Professor of Law at the University of Pennsylvania in Philadelphia Pennsyvania. Jonathan’s work focuses on identifying the causal effects of laws and regulations on individual behavior using cutting-edge econometric tools.
Their guest post, summarizing their research, follows
A number of recent and highly publicized studies have provided evidence that dry and hot summers are strongly correlated with severe fire seasons in the western United States. Among other things, these studies have pointed out a change in western wildfire patterns over roughly the period 1970-2000, with more large fires occurring in relatively high elevation backcountry locations. As this was a period of generally increasing summertime average temperatures, with some years (such as 1988) of extremely unusual heat, drought and wind, there have been increasingly frequent predictions by fire ecologists that global warming will bring a great increase in the frequency of large western wildfires. This is said to be especially of concern in stand-replacing fire regimes such as the Northern Rockies, where historically large, stand-replacing fire regimes have been infrequent.
The problem with studies that correlate the numbers of large western wildfires with summertime weather over recent decades is that such studies ignore several other changes over this period that might be expected to have contributed to an increase in the number of large wildfires. Such variables include a dramatic increase in development near wildland areas and a major shift in firefighting policy by the U.S. Forest and Park Services. Prior to the early 1970’s, Forest and Park Service policy was to strive to put out (suppress) all fires as quickly as possible, even those that were in high elevation, backcountry locations. Work by fire ecologists showed that the suppression of naturally occurring fires was dramatically changing many western forests. In light of this work, the Forest and Park Service changed fire suppression policy during the 1970’s and 80’s and allowed fires in higher elevation backcounty locations to burn within confined areas. However, inevitably, some such fires escaped confinement and became large and very damaging wildfires.
In the paper “Fire Suppression Policy, Weather and Western Wildland Fire Trends: An Empirical Analysis,” (published as a chapter in the volume Wildfire Policy: Law and Economics Perspectives, Bradshaw and Lueck editors, 2012, available at http://www.law.virginia.edu/lawweb/faculty.nsf/FHPbI/3C8E642D085230D685257766006F742A?OpenDocument&ExpandSection=1#_Section1]), Jason Johnston of the University of Virginia and Jonathan Klick of the University of Pennsylvania study the impact of including a measure of fire suppression policy on the estimated statistical relationship between the number of large wildfires in the western U.S. and summertime weather in that region. They find that the change in fire suppression policy toward allowing fires to burn had a significant impact in increasing the frequency of large western wildfires. Perhaps more importantly, Johnston and Klick found that inclusion of the fire suppression policy variable weakened the estimated statistical relationship between summertime weather and large fire frequency. They argue that their results constitute strong evidence that empirical work focusing solely on the relationship between wildfire trends and summertime weather suffers from omitted variables bias. The estimated relationships between wildfire frequency and severity and weather in such studies are not reliable, and may seriously overestimate the significance of climate in explaining wildfire trends. Johnston and Klick’s work implies that the widespread promotion of the results from such studies as conclusively showing that global warming will entail a large increase in the number of western wildland fires is seriously misleading. More fully specified models that control for all potential contributors to wildland fires trends – land development, past timber harvest levels, and fire suppression policy – must be tested before one can assess the relative effectiveness of alternative wildland fire policies. A focus solely on climate change as a cause of wildland fire trends could seriously bias policy by causing too much attention to be focused on greenhouse gas mitigation and too little on changes in fire suppression policy, timber harvest, and land development that might be much more effective in reducing the frequency of large western wildfires.