Coral with Leaves: Millions of Trees Joining the List of Climate Change Casualties

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 Europe.  Global forest mortality has potentially profound ecological and societal implications, given the importance of forests to everything from water supplies, wildlife habitat and food to the global carbon cycle.  Collectively, the world's forests suck up about a quarter of human-caused carbon emissions.

"From a forester's perspective it is a catastrophe.  Environmental services are under threat for an extended period of time," said Klaus Katzensteiner, a forest ecologist at the University of Vienna, Austria.  In many places, he said the global forest changes will affect water flows and water quality, increase wildfire danger and alter the carbon balance of forests for a long time.
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Some scientists have raised concern that the issue is being underestimated.

"We surmise that mortality vulnerability is being discounted in part due to difficulties in predicting threshold responses to extreme climate events," according to a comprehensive forest study published last year in the journal Ecosphere by leading forest and climate researchers.  The research documented tree deaths due to hotter and more frequent droughts, as well as warming feedbacks from forest die-offs.

In the decades of warming ahead, "there are key climate change drivers we know with high confidence will drive forest deaths around the world," the researchers said.

Read more at Coral with Leaves: Millions of Trees Joining the List of Climate Change Casualties