Contributions of Anthropogenic Forcings to Evapotranspiration Changes Over 1980–2020 Using GLEAM and CMIP6 Simulations

Abstract

Anthropogenic impacts on terrestrial evapotranspiration (ET) changes during 1980–2020 were evaluated based on newly released observed‐based GLEAM ET and Coupled Model Intercomparison Project Phase 6 (CMIP6) through optional fingerprint method. Global assessments show that anthropogenic forcings dominate the increasing ET trend, other than natural forcing (NAT). On the global scale, anthropogenic forcings explain ∼84.2% of the observed ET trend, while the signal of natural forcing cannot be detected. Among anthropogenic forcings, greenhouse gases (GHG) are the primary driving factor for ET changes, and GHG‐only has already explained ∼78.8% of the observed ET trend. This study for the first time demonstrates that the GHG signal can be detected in the observed‐based ET and can be separable from NAT and aerosol (AER) signals. At the regional scale, CMIP6 simulations work well in North Hemisphere, but are deficient in South Hemisphere. GHG still dominates ET changes in the North Hemisphere, except for Europe, where the influence of AER forcing stands out, and attributable changes to AER is 2.4 times of GHG. Our first quantitative detection and attribution of ET contribute to advance the understanding of anthropogenic activities on hydrological cycle changes.

Megadroughts in the Common Era and the Anthropocene

“…Anthropogenic climate change affects drought risk and severity through forced changes in precipita tion [171][172][173] , snow 174,175 , and evaporative demand and evapotranspiration 176,177 . Increases in evaporative demand are predominantly caused by warmer temper atures and decreases in relative humidity 31,61,178,179 , with these effects at least partially counteracted by reductions in near surface wind speeds 180 .…”

Detection and Attribution of Human Influence on the Global Diurnal Temperature Range Decline

“…The fingerprint of g i is obtained based on the multimodel ensemble averages of external forcing simulations from CMIP6. The ε represents the internal variability and can be estimated from CTL experiments (Liu, You et al., 2021; Liu, Zhang et al., 2021).…”

“…Recent detection and attribution studies have identified an anthropogenic influence on a series of meteorological and hydrological variables, such as extreme precipitation (Dong et al., 2021; Kirchmeier‐Young and Zhang, 2020; Madakumbura et al., 2021; Paik et al., 2020), temperature (Blackport et al., 2021; Gillett et al., 2021; Wang et al., 2021), drought (Chiang et al., 2021; Williams et al., 2020; Zhang et al., 2021), evapotranspiration (Liu, Zhang et al., 2021), and streamflow (Gudmundsson et al., 2021). However, there are relatively few studies devoted to investigating human influence on the DTR, despite the important implications of changes in the DTR for humans and nature.…”

Soil Moisture and Atmospheric Aridity Impact Spatio‐Temporal Changes in Evapotranspiration at a Global Scale

“…Moreover, these findings are generally associated with large uncertainties due to various data sources used (Wang et al., 2020; Zhang et al., 2016). The overall trends (increasing or decreasing) in global ET since the 1980s are inconclusive across these studies (Liu, Zhang, et al., 2021; Miralles et al., 2014; Wang et al., 2020; Zhang et al., 2016), with a decrease in global ET during 1998–2008 (Jung et al., 2010) and an increasing trend for the period 1982–2011 (Pan et al., 2020) being reported in recent analyses. Changes in ET can be controlled by the available water in the soil (Jung et al., 2010; Zhang et al., 2016), anthropogenic influences (Douville et al., 2013; Sterling et al., 2013), climate variability (i.e., El Niño–Southern Oscillation) (Miralles et al., 2014), increasing temperature (Wang et al., 2022), as well as vegetation greening that controls transpiration (Wang et al., 2021; Zeng et al., 2018; Zhang et al., 2016).…”