Forests around the world are being decimated as the planet grows steadily warmer.
Mass die-offs in California, the Southwest and Europe are not only tied to global warming by new studies, they will add to it.
Just a few years after mountain pine beetles killed millions of acres of lodgepole pine forests in the Rocky Mountains, the U.S. Forest Service is reporting widespread tree deaths in drought-hammered Southern California. Even Europe's cool, moist forests have been losing trees at a fast rate. Large-scale simultaneous forest loss on different continents could have an impact on forests' ability to absorb atmospheric carbon, scientists say.
A recent aerial survey by the U.S. Forest Service tallied 26 million more dead trees in Southern and Central California between last October and April. In those six months, evergreen forests across 1,200 square miles—beset by drought and pine beetles—perished, transforming from living, breathing organisms into sticks of dead tinder and providing fuel for wildfires. In total, the agency has counted 66 million dead trees in the state since 2010.
"We're seeing almost an entire species lost, of the predominant species for this area," said Mariposa County Supervisor Kevin Cann, in a May 23 video by the California State Association of Counties. "It's inevitable that you want to deny this reality. You don't want to believe that your entire ponderosa forest can be wiped out. This summer, we're going to hold our breath for a while and try to be really prepared to react as fires happen."
Scientists have increasingly linked forest mortality with climate impacts—and in Southern California, it is most directly tied to a steady increase in droughts that weaken trees, making them more susceptible to pine beetles. A 2015 study in the journal Geophysical Research Letters found that human-caused warming "substantially increased the overall likelihood of extreme California droughts."
Widespread climate impacts to forests have also been documented in other regions, including the Southwest, and in Euro