Environmental Policy

Dannenberg to Study Anthropogenic Warming as Summer Scholar

Photo of Dannenberg

Matthew Dannenberg, assistant professor of Geographical and Sustainability Sciences, joins the PPC as a summer scholar-in-residence, to work on his project, "Contributions of Anthropogenic Warming to Drought-Induced Loss of Vegetation Health." 

Droughts are among the world’s costliest natural disasters, damaging both social and ecological systems. Anthropogenic warming exacerbates natural precipitation deficits through heat-induced increases in evaporative demand, which further dries soils and stresses vegetation. Roughly 15-20% of soil moisture loss during the 2012-2015 California drought, for example, was directly attributable to anthropogenic warming. While this drought clearly reduced vegetation health, the proximate climatic drivers (e.g., extreme heat vs. soil moisture loss) and relative contributions of natural variability vs. anthropogenic forcing remain unknown. Dannenberg proposes to quantify anthropogenic contributions to drought-induced loss of vegetation health. He hypothesizes that anthropogenic threats to vegetation during the 2012-2015 California drought were even greater than their contributions to loss of soil moisture due to the direct negative effects of higher temperatures and vapor pressure deficits (VPD) on vegetation health. Preliminary results suggest that nearly 50% of reduced vegetation health during the drought was directly attributable to anthropogenic warming, primarily driven by anthropogenic increases in temperature and VPD. This clearly shows that while droughts are generally initiated by natural variability of precipitation, anthropogenic warming exacerbates these conditions, nearly doubling the effect of drought on plant health and productivity.

Dannenberg will refine the preliminary workflow, apply the method to additional satellite-based indicators of vegetation health, and write a manuscript on anthropogenic contributions to drought-induced loss of vegetation health for submission to Nature Climate Change and will write and disseminate a policy-relevant fact sheet and present the research at two conferences and at a Lunch and Learn.

To view his project proposal, click here.