Abstract
Vegetation plays a vital role in the Earth system by sequestering carbon, producing food and oxygen, and providing evaporative cooling. Vegetation productivity extremes have multi-faceted implications, for example on crop yields or the atmospheric CO2 concentration. Here, we focus on productivity extremes as possible impacts of coinciding, potentially extreme hydrometeorological anomalies. Using monthly global satellite-based Sun-induced chlorophyll fluorescence data as a proxy for vegetation productivity from 2007–2015, we show that vegetation productivity extremes are related to hydrometeorological hazards as characterized through ERA5-Land reanalysis data in approximately 50 % of our global study area. For the latter, we are considering sufficiently vegetated and cloud-free regions; and we refer to hydrometeorological hazards as water or energy related extremes inducing productivity extremes. The relevance of the different hazard types varies in space; temperature-related hazards dominate at higher latitudes with cold spells contributing to productivity minima and heat waves supporting productivity maxima, while water-related hazards are relevant in the (sub)tropics with droughts being associated with productivity minima and wet spells with the maxima. Next to single hazards also compound events such as joint droughts and heat waves or joint wet and cold spells play a role, particularly in dry and hot regions. Further, we detect regions where energy control transitions to water control between maxima and minima of vegetation productivity. Therefore, these areas represent hot spots of land-atmosphere coupling where vegetation efficiently translates soil moisture dynamics into surface fluxes such that the land affects near-surface weather. Overall, our results contribute to pinpoint how potential future changes in temperature and precipitation could propagate to shifting vegetation productivity extremes and related ecosystem services.
Highlights
Vegetation is a crucial component of the Earth system because it provides ecosystem services like food and oxygen production, CO2 sequestration and evaporative cooling
In addition to vegetation productivity, we study changes related to vegetation greenness by using satelliteobserved enhanced vegetation index (EVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS; Didan, 2015)
In approximately 50 % of the global study area, we find that vegetation productivity extremes are associated with hydrometeorological hazards
Summary
Vegetation is a crucial component of the Earth system because it provides ecosystem services like food and oxygen production, CO2 sequestration and evaporative cooling. Many studies investigated the influence of such hazards on vegetation productivity, highlighting their impact on the biosphere (Ciais et al, 2005; Zhao and Running, 2010; Zscheischler et al, 2013, 2014a, b; Flach et al, 2018; Wang et al, 2019; Zhang et al, 2019; Qiu et al, 2020). Usually these studies focus on particular types of hydrometeorological hazards such as droughts or heat waves, or they use vegetation productivity data from models or other proxies rather than the recent satellite-derived Sun-induced chlorophyll fluorescence (SIF) data (Frankenberg et al, 2011; Joiner et al, 2013).
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