Climate change is causing not only shifts in annual total rainfall and mean temperature, but also changes in rainfall and temperature variance. Namely, rain events are becoming more intense and less frequent, and droughts and heatwaves are becoming more frequent. The terrestrial biosphere takes up a quarter of anthropogenic carbon emissions, but this biosphere uptake has an interannual variability and uncertain trend that is largely driven by climate. Therefore, it is critical to understand how vegetation-soil systems respond to climate variability. Similarly, since global model predictions are subject to uncertain water and carbon cycle coupling, it is essential to observe biospheric responses at large scales with diverse remote sensing platforms.
In this seminar, I ask: how do land surfaces respond to climate variability and change? Does increased climate variability lead to increased land surface variability? Which physical mechanisms drive these responses? I will address these questions in summarizing two recent investigations that use satellite remote sensing: (I) the observed response of global vegetation to shifting rainfall frequency and intensity as well as (II) the observed responsiveness of landscapes to climate variability. I show how drylands emerge as hotspots for strong responses to climate forcing and change. I also discuss how rain pulses and consequent drydowns reveal underlying mechanisms that describe the land surface responses. Ultimately, rainfall intermittency shifts will cause 10-20% changes of global photosynthesis of varying sign, with the strongest responses in drylands. Furthermore, these observations inform Earth system model parameterizations and outputs.
Andrew Feldman is a NASA Postdoctoral Program Fellow in the Biospheric Sciences Laboratory at the NASA Goddard Space Flight Center located in Greenbelt, MD. He is a hydrologist who studies the coupling of the terrestrial water, carbon, and energy cycles mainly using satellite remote sensing platforms. His efforts also include developing and investigating satellite remote sensing retrieval algorithms to better observe the terrestrial biosphere. Prior to joining NASA, Andrew was a graduate research assistant at Massachusetts Institute of Technology, Cambridge, MA, where he received S.M. and Ph.D. degrees in civil and environmental engineering in 2018 and 2021, respectively. He also completed his bachelor’s and master’s degrees in civil engineering from Drexel University in Philadelphia, PA in 2016.