Note: This was originally submitted to the LA Times and rejected.
Unfortunately, “A wildfire plan that makes things worse” has misrepresented a number of the findings from the scientific community that provide the basis for the Forest Carbon Plan and Governor Brown’s proposal.
Governor Brown’s May 10 proposal represents a forward-looking policy response to the challenges facing California’s forests and communities. The forests of the Sierra Nevada are facing a number of challenges including hotter temperatures, drought, insect outbreaks, and uncharacteristic wildfire. Numerous scientific studies in the Sierra Nevada have documented that mid- and low-elevation forests were historically maintained by frequent surface and mixed-severity fires that killed individual or small groups of trees. The forests we have today are the result of a century of fire suppression. The large wildfires burning today are uncharacteristic for these forests because they kill large patches of trees. Large, hot wildfires negatively impact wildlife habitat for some species like the California spotted owl and Pacific fisher, they kill the vegetation on steep slopes that stabilizes soil and protects water quality, and they decrease the amount of carbon that these forests remove from the atmosphere and store. Large patches of fire-killed trees can be a source of carbon to the atmosphere for decades, contributing to climate change. Studies across the western US show that as global warming has increased, the fire season has gotten longer. More large wildfires are occurring across the west and in California. With continued warming, we expect this trend to continue.
Many studies have demonstrated that we can reduce the risk of large, tree-killing wildfires by using a combination of thinning and prescribed fire. In some locations, such as adjacent to communities thinning prior to burning is required to reduce fire hazard. In other locations, fire alone can do the necessary work to restore these forests. Thinning can in fact remove many trees, but the type of thinning the Governor’s proposal includes is focused on small trees. This is an important point because large trees remove more carbon from the atmosphere and store more carbon than small trees. Further, trees compete for resources and when there is a drought and large trees are competing with small trees for water, they become stressed and more susceptible to insects and death. California’s most recent drought demonstrated this fact, with 102 million dead trees in the Sierra.
Hanson and Miller also misrepresent our scientific understanding of forests, fire, and carbon. While true that only a small fraction of a live tree killed by wildfire is combusted during the fire, they do not acknowledge the basic fact that live trees remove carbon from the atmosphere and dead trees emit carbon to the atmosphere.
My research group has conducted studies at both the watershed scale and for the entire Sierra Nevada to evaluate the influence of these treatment options on the ability of the forest to remove carbon from the atmosphere and store it. Our results show that thinning and burning treatments do reduce the amount of carbon stored in the forest in the near-term. However, over time a more natural forest condition stores much more carbon than the overly-dense forests we currently have. The two determining factors are the proportion of trees killed by wildfire and the size of harvested trees.
When we reduce tree density and restore surface and mixed-severity fire, we significantly reduce the chance of a large, tree-killing wildfire. When wildfire burns through treated forest, many more trees survive the fire and continue helping to regulate the climate by removing carbon from the atmosphere. Our research demonstrates that because we expect more wildfire with more climate change, implementing these treatments over a larger area at a faster pace leads to lower total wildfire emissions and more carbon stored in Sierran forests.
Investing in reducing the risk of large, tree-killing wildfires in the Sierra Nevada carries both ecological and societal benefits. The scientific community has done the research to identify management options that will benefit forests.
Governor Brown’s proposal is based on decades of scientific research. It acknowledges that the climate is changing and that California’s forests will be significantly challenged by continued warming. The proposal also recognizes the role of California’s forests in regulating the climate and that forest management based on scientific evidence can help sustain these forests and the services that they provide to society.