Aridification risks of global ecohydrological element increases under
climate change
Abstract
Drought is the most widespread climatic extreme that has negative
impacts on ecohydrology. Studies have shown that drought cause certain
degrees of disturbances to different ecohydrological elements, but the
magnitude with which drought leads to changes in ecohydrological
elements at the global scale remains largely unknown. At the same time,
it is not clear what kind of drought risk will be suffered by
ecohydrological elements in the future under a high-concentration
greenhouse gas emission scenario. Here, we derived the thresholds of
evapotranspiration (ET), soil moisture (SM), the vapor pressure deficit
(VPD), and the normalized difference vegetation index (NDVI) to drought
in the historical period (1982-2015) and revealed the projected drought
risks of the above ecohydrological elements. We found that a decrease in
SM caused by drought is often accompanied by an increase in VPD in the
area, and ET and NDVI are expected to decrease under drought conditions
in most parts of the world due to increases in radiation (RAD) and
temperature (TEMP) and decreases in SM during drought periods. When a
drought lasted for 8-15 months and the corresponding drought severity
reached 10-15, the drought caused changes in ecohydrological elements in
most regions of the world. Compared with arid and semiarid regions,
different ecohydrological elements are more sensitive to drought in
humid and semihumid regions. Compared with 1982-2015, the drought risk
of ecohydrological elements will increase gradually in the next three
periods. By 2071-2100, more than half of the world’s ecohydrological
elements will be more susceptible to drought disturbances.