Tropical forests are essential for absorbing carbon dioxide from the atmosphere. But it is also subject to severe storms that can cause “windfall” – the uprooting or breaking of trees. These fallen trees are decomposing, which can turn the forest from a carbon sink into a source of carbon.
A new study finds that severe thunderstorms caused by climate change will likely lead to a greater number of large windfall events in the Amazon rainforest. This is one of the few ways researchers have developed a link between storm conditions in the atmosphere and forest death on Earth, helping to fill in a major gap in the models.
“Building this link between atmospheric dynamics and surface damage is very important across the board,” said Jeff Chambers, chief scientist at DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab) and director of the Next Generation Ecosystem Experiments. (NGEE) – The Tropical Project that conducted the research. “It’s not just for the tropics. It’s high latitude, low latitude, temperate latitude, right here in the United States.”
The researchers found that the Amazon region will be 43% more likely to experience larger blasting events (25,000 square meters or more) by the end of the century. The Amazon is likely to experience severe storms that will bring significant rainfall and gusts of wind that will also increase by about 50%. The study has been published in the journal Nature Communications on January 6th.
“We want to know what these intense storms and wind gusts mean in terms of the carbon budget and carbon dynamics, carbon sinks in forests,” Chambers said. While deciduous trees slowly release carbon as they decompose, the open forest becomes host to new plants that pull carbon dioxide from the air. “It’s a complex system, and there are still a lot of puzzle pieces we’re working on. To answer the question more quantitatively, we need to build the Earth-atmosphere links into Earth system models.”
To find the link between the air and the ground, the researchers compared a map of more than 1,000 major earthquakes with atmospheric data. They found that a measurement known as CAPE, “convectively available potential energy,” was a good predictor of the Big Bang. CAPE measures the amount of energy available to move parcels of air vertically, and a high value of CAPE often results in thunderstorms. Severe storms can come with strong vertical winds and heavy rain or hail and lightning, which interact with the trees from the canopy to the soil.
“Storms account for more than half of the forest mortality rate in the Amazon,” said Yanli Feng, first author of the paper. “Climate change has a significant impact on the Amazon forest, but so far, much of the research focus has been on droughts and fires. We hope that our research will bring more attention to severe storms and improve our models for working within an environment that is changing from climate change.”
While this study looked at a future with high carbon emissions (a scenario known as SSP-585), scientists can use projected CAPE data to explore the effects of wind clouds in different emissions scenarios. The researchers are now working to incorporate the new forest storm relationship into Earth system models. Better models will help scientists explore how forests will respond to a warmer future — and whether they can continue to draw carbon from the atmosphere or become a contributor instead.
“This was a very influential climate change study for me,” said Feng, who completed the research as a graduate student in the NGEE-Tropics project at Berkeley Lab. She now studies carbon capture and storage at the Carnegie Institution for Science at Stanford University. “I am concerned about the expected increase in forest disturbances in our study and hope that I can help reduce climate change. So now I am working on solutions to climate change.”
NGEE-tropics It is a ten-year, multi-institutional project funded by the US Department of Energy’s Office of Science, Bureau of Biological and Environmental Research.