Open AccessLarge Divergence in Tropical Hydrological Projections Caused by Model Spread in Vegetation Responses to Elevated CO 2
Author(s) -
Zhou Sha,
Keenan Trevor F.,
Williams A. Park,
Lintner Benjamin R.,
Zhang Yao,
Gentine Pierre
Publication year - 2022
Publication title -
earth's future
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.641
H-Index - 39
ISSN - 2328-4277
DOI - 10.1029/2021ef002457
Subject(s) - environmental science , water cycle , evapotranspiration , vegetation (pathology) , climatology , precipitation , climate model , atmospheric sciences , climate change , atmosphere (unit) , atmospheric model , transpiration , ecology , geography , meteorology , geology , biology , medicine , photosynthesis , botany , pathology
Increasing atmospheric CO 2 and associated global warming are expected to alter the global hydrological cycle, thereby posing widespread threats to freshwater availability. However, future hydrological projections differ greatly between models, particularly over the tropical regions. The large difference between model projections directly limits policy planning efforts, and the responsible modeling processes remain unclear. Here, we identify the primary processes accounting for model differences in tropical hydrological changes using multiple CO 2 sensitivity experiments in the Coupled Model Intercomparison Project. We show that differences in projected changes to tropical evapotranspiration, precipitation, and surface water availability mainly arise from model representations of vegetation cover and stomatal conductance responses to elevated CO 2 and associated changes in atmospheric moisture and circulation. Atmospheric responses to sea surface warming contribute additionally to the divergence in hydrological projections. Given the importance of vegetation responses to elevated CO 2 and associated atmosphere feedbacks, our results underscore the need to improve representations of the vegetation physiological response to rising CO 2 and its coupling to the atmosphere, to provide reliable tropical hydrological projections.