T38 Assessing Causes, Consequences, and Time Scales of Miocene Climate and Environmental Change

Sunday, 10 October 2021
1:30 PM - 5:30 PM
E141/E142 (Hybrid Room)

SENSITIVITY OF SOUTH AMERICAN PRECIPITATION TO MIOCENE CO2 VARIATIONS AND EASTERN ANTARCTIC GLACIATION

Paper number: T38-3
Program: Technical Sessions
Time: 1:50 PM – 2:05 PM

Authors

Abstract

Recent work shows a strong coupling between CO2 and temperature across the Miocene suggesting that CO2 is the main controlling factor behind global climate variation during this time. Here, we performed a series of sensitivity experiments with the Community Earth System Model and published Miocene boundary conditions to understand the sensitivity of South American precipitation to long-term Miocene CO2 variations and establishment of an expansive eastern Antarctic ice sheet at the mid-Miocene Glaciation (MMG). These simulations feature CO2 variations equivalent to radiative forcings ranging from 1 to 2.5 W/m2 for pre-MMG and from 0 to 1.5 W/m2 for post-MMG relative to preindustrial. For both pre-MMG and post-MMG, annual mean mid-latitude (between ~30° and 40°S) precipitation scales positively with CO2 forcing but negatively with glacial forcing. In contrast, across South American monsoon region (~10° to 20°S), annual mean precipitation shows muted dependency on CO2 forcing, but responds strongly to MMG glaciation, epitomized in a southward shift in South Pacific Convergence Zone. Taken together, these experiments reveal a clear spatial distinction between these two precipitation regimes in response to CO2 forcing and glaciation: mid-latitude precipitation responds positively with CO2 forcing but negatively to eastern Antarctic glaciation. In contrast, south American monsoon region shows resistance to CO2 forcing, but sensitivity to eastern Antarctic glaciation. Future work will engage Miocene hydroclimate records to test this model paradigm.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-368439

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