Past terrestrial hydroclimate driven by Earth System Feedbacks

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Ran Feng


Geologic evidence suggests drastic reorganizations of subtropical terrestrial hydroclimate during past warm intervals, including the mid-Piacenzian Warm Period (MP, 3.3 to 3.0 Ma). Despite having a similar to present-day atmospheric CO2 level (pCO2), MP featured moist subtropical conditions with high lake levels in Northern Africa, and mesic vegetation and sedimentary facies in subtropical Eurasia. Here, we demonstrate that major loss of the northern high-latitude ice sheets and continental greening, not the pCO2 forcing, are key to generating moist terrestrial conditions in subtropical Sahel and east Asia. In contrast to previous hypotheses, the moist conditions simulated in both regions are a product of enhanced tropospheric humidity and a stationary wave response to the surface warming pattern, both varying strongly in response to land cover changes. These results suggest that past terrestrial hydroclimate states were driven by Earth System Feedbacks, which may outweigh the direct effect of pCO2 forcing.



Physical Sciences and Mathematics


Pliocene, CMIP6, Terrestrial hydroclimate, earth system feedback, PlioMIP2


Published: 2021-06-18 01:55

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CC BY Attribution 4.0 International

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Conflict of interest statement:

Data Availability (Reason not available):
PlioMIP2 simulations that are part of the Climate Model Intercomparison Project 6 (CMIP6) can be found via Earth System Grid Federation: EC-Earth3: IPSL-CM6A-LR: GISS-E2-1-G: CESM2: HadGEM3: The sensitivity simulations with CESM2 are available on Cheyenne supercomputer (will be transferred to a public database upon publication of this manuscript).

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