Cal Forests and climate change

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Impacts of Climate Change on California Forests
Scientists around the world agree that the phenomenon of global climate change is happening now, and most agree that it is chiefly caused by human actions. There has been less certainty about the effects of climate change on particular regions, however, due to the many variables that must be accounted for in computer models. Quite a few articles and reports have focused on what changes California can expect to see as a result of global warming. (See Selected Resources.)	View over the mountains at dusk, Klamath National Forest. Photograph courtesy USDA Forest Service.
In an article published in the Proceedings of the National Academy of Sciences on Aug. 16, 2004, "Emissions pathways, climate change, and impacts on California," scientists used two computer models to forecast the possible effects of climate change on the state. "By the end of the century [according to one model] heatwaves and extreme heat in Los Angeles quadruple in frequency while heat-related mortality increases two to three times; alpine/subalpine forests are reduced by 50-75%; and Sierra snowpack is reduced 30-70%. [In another scenario], heatwaves in Los Angeles are six to eight times more frequent, with heat-related excess mortality increasing five to seven times; alpine/subalpine forests are reduced by 75-90%; and snowpack declines 73-90%, with cascading impacts on runoff and streamflow that, combined with projected modest declines in winter precipitation, could fundamentally disrupt California's water rights system."
Water Water is key in California. Even without the many other disruptions from climate change, the state’s water resources have been stretched to the limit. Changes in the amount of precipitation the state receives, and, crucially, the amount it can use, will affect agriculture, urban populations, wildlife and forests. Confronting Climate Change in California, a report put out by the Union of Concerned Scientists and The Ecological Society of America, predicts that Californians will see much warmer, wetter winters and only slightly warmer but much drier summers as the most likely result of continued global warming. With warmer winters, more precipitation will fall as rain than as snow, and this will affect the flow of rivers and streams in the state. Since the soil quickly becomes saturated in winter, the additional rainfall will mean more runoff. And since there will be less snow, there will be less snowmelt in spring and summer, leading to lowered river and stream flows and drier conditions downstream. Shifting ecosystems An important effect of increasing temperatures will be the changes in ecosystems as plant and animal species succeed or fail in migrating to stay within suitable climate. "Climate change will inevitably shift the suitable range for each type of ecosystem, as well as the mix of plants and animals at the vital focus of energy and nutrients that occur within them."—Confronting Climate Change in California. But some species may not be able to migrate if suitable habitat no longer exists. Species adapted to an alpine climate, for instance, might not be able to find comparable conditions in a warmer world. "…5 percent to 10 percent of California native plant species would no longer find suitable temperature conditions within the state if average temperatures warmed 5 to 6 degrees F." —Confronting Climate Change in California And in the most populated state in the country, a considerable amount of habitat has been fragmented by development—urban sprawl, ranches, vineyards, farms, highways. So even if suitable habitat exists somewhere, species may be blocked in their attempts to migrate to it.
Forest fire. Photo by Bob Nichols, USDA.	More fires Another consequence of hotter drier summers could be a rise in the frequency and severity of forest fires in California. As the state heats up, forests will tend to shift northward and uphill to cooler climes. Many scientists fear the forests may not be able to migrate rapidly enough, leaving large areas of dry, dying trees susceptible to intense blazes. A hotter, drier climate, with more Santa Ana winds and drier summers, might well lead to more fires in Southern California forests. "In dying forests, the threat of fire becomes much greater, and intense wildfires may become more frequent, widespread and destructive," says a report by the National Center for Ecological Analysis and Synthesis titled "Climate Change and Variability in California." Changes in rainfall and water flow could cause drought conditions in some parts of the state. Without sufficient water, forests would also be stressed and more vulnerable to damaging insects such as pine bark beetles.
El Niño A rise in "El Niño-like" storms, and consequent increased flooding in coastal and delta areas, is predicted by several studies. It is also possible (though by no means certain) that changes in surface ocean temperature could affect the frequency and density of coastal fog. If this scenario came to pass, coastal redwoods, which get a good deal of their annual ration of moisture from fog, could eventually disappear from the coast ranges. In the case of long-lived trees such as the redwoods, the damage might not be immediately apparent.	Ocean temperatures during an El Niño event. Graphic courtesy National Oceanic and Atmospherics Administration.
Ponderosa pines damaged by pine bark beetles. Photo by Kenneth E. Gibson, USDA Forest Service.	"Individual redwoods may survive for centuries, even millennia," according to Confronting Climate Change in California, "long past the point where climate changes make growth of new seedlings impossible." These doomed forests are known as "museum" populations, wherein individual trees seem healthy, but are no longer able to reproduce. Gains and losses The increase in carbon dioxide, and the increased average temperatures, could actually increase forest productivity, at least in the short run. But drier climate, changes in water flow, increased frequency and severity of forest fires, and increased vulernability to pest outbreaks could cancel out these gains. Forest Impacts According to Global Climate Change and California: Potential Impacts and Responses (ed. Joseph B. Knox, University of California Press, 1991), some possible impacts of climate change on California’s forests include: elimination of Douglas-fir from lowlands due to loss of winter chill conditions needed for germination and growth;
increased fuel loading due to Douglas-fir mortality; widespread movement of forests upslope from their present locations; increased productivity of redwood in northern areas, but reduction of redwood range in southern areas if precipitation decreases; increased rates of decomposition and nutrient release from litter; succession in forest gaps by shrub species such as ceanothus and alder, leading to an increase in spatial vegetation diversity; wildlife habitat changes favoring species that take advantage of gaps and dead wood; likely deterioration of stream water quality due to increased rates of decomposition, weathering and erosion caused by tree mortality. Early responders Scientists, land managers, and others who will be on the front lines of global climate change in coming years have begun to think about ways to respond to these changes. Many state government agencies that deal with the environment are beginning to incorporate responses to the threat of global warming in their planning. The California Energy Commission is responsible for coordinating climate change issues in the stare. Their webpage lists the various state agencies that are attempting to respond to global climate change. The California Department of Forestry, for instance, has announced its intention to preserve the carbon storage capabilities of woodlands under its control. The agency says it plans to retain older, larger trees, since these have the greatest carbon storage capacity. (How this will play out in light of the CDF's historical propensity to cater to the timber industry, and to pad its own budget through logging projects on state forests, is yet to be seen. Industrial logging could be given cover by "fuels management" and "thinning " projects undertaken as part of a global-warming response.) The agency also is involved in urban forestry, and works with private landowners, advising them on how to maximize carbon storage capacity in their woodlands. The Department of Fish and Game, anticipating the dislocation of habitat that will be caused by global warming, is taking an ecosystem approach in its conservation planning, trying to protect large areas containing a diversity of habitats to allow for migration of species faced with habitat change. The State of California has devoted a website (http://www.energy.ca.gov/global_climate_change/index.html) to global climate change and the state's response.

What You Can Do

Global climate change is happening now. The international community is still not unified in its response, but given the serious long-term consequences of inaction, we should do whatever we can, as soon as we can.

The shrinking of the ozone hole that has followed adoption of the Montreal Protocol's limits on CFC emissions shows that human actions can reverse large-scale environmental problems.

What actions can we take to help avert global warming? What strategies should be put in place to mitigate the effects of sudden climate change?

The first thing we all can do is to make sure our government representatives understand the importance of global warming. Support pubic officials who demonstrate an awareness of the problem. Let your representatives know that you are concerned, and are willing to vote that concern.

Actions against climate change:

Limit fossil fuels: Use fuel-efficient vehicles. Promote mass transit alternatives. Promote alternative energy sources (solar, wind, fuel-cell).

Limit development: We need to preserve as much forest as we can, both as a carbon sink, and to provide habitat corridors for species migrating in response to global warming. Fighting sprawl development can both help preserve wild lands and cut down on the use of fossil fuels.

Plan for the future: Design nature reserves to accommodate future climate change, provide wildlife migration corridors. Restore degraded habitat.

Educate yourself: Learn all you can about the causes and potential effects of global climate change.

Global Climate Change

Forests and Climate Change

Selected Resources

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Impacts of Climate Change on California Forests