Climate change is wiping out forests on a staggering scale
California’s multiyear drought killed even more trees than previously thought, the U.S. Forest Service announced this week. Aerial and ground surveys show that 26 million trees across six counties in Southern California died, in addition to the 40 million trees that died statewide from 2010 to October 2015. Four years of drought, high temperatures and an outbreak of tree-killing bark beetles all contributed the historic levels of tree die-off, the agency said.
The tree mortality in California is the latest crest in a wave of forest die-offs in the past few decades linked with global warming. In the Southwest, an outbreak of ips beetles after the 2002 drought killed 80 percent of the piñon pine forests in the Four Corners region.
Around the same time, pine beetles started spreading across northern Colorado, parts of Wyoming and North Dakota, ultimately killing millions of acres of forest. And just as the pine beetle infestation waned, a spruce beetle outbreak in southern Colorado started to spread. Since 1996, spruce beetles have killed trees across about 1.5 million acres of forest.
Huge swaths of Colorado aspen forests also died in the early 2000s in a mortality event linked with extreme heat, and forest researchers say hardwood forests in the northern U.S. are also at risk from global warming.
“Tree dies-offs of this magnitude are unprecedented and increase the risk of catastrophic wildfires that puts property and lives at risk,” said Agriculture Secretary Tom Vilsack. “While the fire risk is currently the most extreme in California because of the tree mortality, forests across the country are at risk of wildfire and urgently need restoration requiring a massive effort to remove this tinder and improve their health,” Vilsack said, once again urging Congress to make resources available for forest treatments.
“Unfortunately, unless Congress acts now to address how we pay for firefighting, the Forest Service will not have the resources necessary to address the forest die-off and restore our forests. Forcing the Forest Service to pay for massive wildfire disasters out of its pre-existing fixed budget instead of from an emergency fund like all other natural disasters means there is not enough money left to do the very work that would help restore these high mortality areas. We must fund wildfire suppression like other natural disasters in the country,” Vilsack said.
Forest Service scientists expect to see continued elevated levels of tree mortality during 2016 in dense forest stands, stands impacted by root diseases or other stress agents and in areas with higher levels of bark beetle activity. Additional surveys across the state will be conducted throughout the summer and fall.
With the increasing size and costs of suppressing wildfires due to climate change and other factors, the very efforts that would protect watersheds and restore forests to make them more resilient to fire in the future are being squeezed out of the budget. Last year fire management alone consumed 56 percent of the Forest Service’s budget.
Learn more about tree mortality and the work to restore our forests in California at the Forest Service’s web page Our Changing Forests.