From the perspective of economic loss and ecological impact, droughts are one of the most significant climate extremes. While the impacts of single droughts on forests have been widely studied, understanding whether forests acclimate to or become more vulnerable to drought events remains largely unknown and is crucial for predicting future forest health, which carries significant implications for fire behavior. As climate models predict an increase in the frequency and severity of drought, the response of ecosystems to climate extremes represents an important uncertainty in carbon-cycle feedback and may have the potential to alter terrestrial ecosystems from a net sink to a carbon source over the twenty-first century.
In a new Nature Climate Change article, authors William R. L. Anderegg , Anna T. Trugman , Grayson Badgley, Alexandra G. Konings, and John Shaw combine forest datasetsof tree growth, tree mortality and ecosystem water content to analyze the effects of multiple droughts at a range of scales from individual trees to the globe from 1900 to 2018. It was found that multiple droughts have a more detrimental impact than initial droughts, but this effect differs largely by clade and ecosystem. With gymnosperms and conifer-dominated ecosystems more often exhibiting increased vulnerability to multiple droughts, the differential impacts of multiple droughts on different clades and biomes show that drought frequency changes may have fundamentally different ecological and carbon-cycle consequences across ecosystems.
Funding for this project was provided by the NOAA Climate Program Office, MAPP program.
The Modeling, Analysis, Predictions, and Projections (MAPP) Program is a competitive research program in NOAA Research’s Climate Program Office. MAPP’s mission is to enhance the Nation’s and NOAA’s capability to understand, predict, and project variability and long-term changes in Earth’s system and mitigate human and economic impacts. To achieve its mission, MAPP supports foundational research, transition of research to applications, and engagement across other parts of NOAA, among partner agencies, and with the external research community. MAPP plays a crucial role in enabling national preparedness for extreme events like drought and longer-term climate changes. For more information, please visit www.cpo.noaa.gov/MAPP.