There’s a mystery inside trees upon which the fate of coastal cities, threatened by rising sea levels from climate change, may depend. Each year, the Earth’s forests take up about one-quarter of the carbon dioxide emitted by humans, effectively slowing the speed and severity of global warming. They lock up most of this carbon in their stems and keep it there for centuries. This service that they provide to humanity is worth about U.S. $1 trillion each year.
But there’s no guarantee that trees around the globe will continue to do this in coming decades. Climate change is superfueling droughts, massive wildfires, and insect outbreaks, all of which slow trees’ growth, kill trees, and release this carbon back into the atmosphere.
Thus, the $1 trillion question that scientists are racing to answer is—what is the fate of trees in a changing climate?
In a study of the impact of droughts on trees, my colleagues and I focused on one aspect of this question, specifically the impact of drought on trees. Our analysis shows that forests do not rebound from extreme drought as quickly as scientists had thought—a finding that could lead to better models for how forests absorb carbon emissions.
Reading Tree History
Currently, we’re largely flying blind when it comes to forecasting the fate of trees. Our best predictive tools—mathematical models based on plant physiology and climate—disagree wildly on the future of forests.
Some show that trees continue to grow like crazy and take up carbon through the end of the century. In others, however, drought, temperature, and other ecosystem disturbances dampen tree growth and kill many trees, and ecosystems begin to lose carbon, rapidly accelerating the speed and severity of climate change. Worse still, these models are generally not thought to accurately simulate drought impacts on forests.
