labs_title

Global patterns of drought recovery

C.R. Schwalm, W.R.L. Anderegg, A.M. Michalak, J.B. Fisher, F. Biondi, G. Koch, M. Litvak, K. Ogle, J.D. Shaw, A. Wolf, D.N. Huntzinger, K. Schaefer, R. Cook, Y. Wei, Y. Fang, D. Hayes, M. Huang, A. Jain and H. Tian

In this work, we examine trends in drought recovery over the last hundred years, and finds that drought recovery times are strongly associated with climate and carbon cycle dynamics. We also find that drought recovery is longest in the tropics and high northern latitudes, which are both vulnerable areas of Earth’s climate system, and that drought impacts, as defined by area in active drought recovery, have increased over the twentieth century.


Figure: Spatial pattern of drought recovery time. Recovery time by grid cell across all combinations of GPP and integration time. White areas are water, barren, or did not experience any relevant drought events.

Abstract

Drought, a recurring phenomenon with major impacts on both human and natural systems, is the most widespread climatic extreme that negatively affects the land carbon sink. Although twentieth-century trends in drought regimes are ambiguous, across many regions more frequent and severe droughts are expected in the twenty-first century. Recovery time—how long an ecosystem requires to revert to its pre-drought functional state—is a critical metric of drought impact. Yet the factors influencing drought recovery and its spatiotemporal patterns at the global scale are largely unknown. Here we analyse three independent datasets of gross primary productivity and show that, across diverse ecosystems, drought recovery times are strongly associated with climate and carbon cycle dynamics, with biodiversity and CO2 fertilization as secondary factors. Our analysis also provides two key insights into the spatiotemporal patterns of drought recovery time: first, that recovery is longest in the tropics and high northern latitudes (both vulnerable areas of Earth’s climate system) and second, that drought impacts (assessed using the area of ecosystems actively recovering and time to recovery) have increased over the twentieth century. If droughts become more frequent, as expected, the time between droughts may become shorter than drought recovery time, leading to permanently damaged ecosystems and widespread degradation of the land carbon sink.

Schwalm, C.R., W.R.L. Anderegg, A.M. Michalak, J.B. Fisher, F. Biondi, G. Koch, M. Litvak, K. Ogle, J.D. Shaw, A. Wolf, D.N. Huntzinger, K. Schaefer, R. Cook, Y. Wei, Y. Fang, D. Hayes, M. Huang, A. Jain, H. Tian (2017) "Global patterns of drought recovery", Nature, 548 (7666), 202–205, doi:10.1038/nature23021