Summit County Citizens Voice

Most mature lodgepoles pines in Summit County have already been killed by an insect outbreak that is probably linked to global warming.

New study looks for patterns in global forest die-offs

By Summit Voice

SUMMIT COUNTY — Colorado’s forests, under attack by insects and weakened by increasing heat and drought, are not the only forests that may be feeling the impacts of climate change.

In North Africa, a massive die-off of cedars has been linked to drought, and El Niño-fueled droughts have hit forests in Malaysia and Indonesia. Australian eucalyptus forests have also been seen drought impacts, and forests around the Mediterranean have also suffered.

These different examples of drought and heat-related tree mortality suggest that no forest types and climate zones are immune to global warming impacts, even in environments not considered to be water-limited. Trees subject to heat stress can die of carbon starvation and not just lack of water, a recent U.S. Geological Survey study concluded after surveying the status of forests around the world.

But despite the multitude of forest studies, there is still not enough data to determine any global forest trends linked to climate change. That in itself is a problem for policy and decision makers, who need to consider the impacts of massive forest die-offs as they try to prepare and adapt for a warmer world.

The studies do suggest that some of the observed changes are consistent with projections of increased forest mortality, and that some forest ecosystems are already shifting in response to a changing climate.

The research was compiled by a team led by U.S. Geological Survey scientist Craig Allen, who will be discussing the findings at the Feb. 18 For the Forest Symposium in Aspen. Allen’s study is one of the first global assessments of recent tree mortality attributed to drought and heat stress. The results indicate that, “at least some of the world’s forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought.”

The study also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system. Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide.

even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system.

“Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide,” the authors conclude in the abstract.

It wasn’t hard for the researchers to find examples of forest mortality related to heat and drought, with at least 88 recent examples (since 1970) of events that fit the criteria of being driven by water and heat stress. The examples ranged from modest but significant local increases in tree mortality rates to climate-driven episodes for regional forest die-offs.

Filed under: climate and weather, Colorado, El Niño, Environment, Forest health, forests, global warming, La Niña, pine beetles Tagged: | climate change, Environment, Forest health, global warming, Summit County, Summit County News