Climate response at the Paleocene-Eocene Thermal Maximum to greenhouse gas forcing - A model study with CCSM3
The Paleocene-Eocene Thermal Maximum (PETM; 55 Ma) is of particular interest since it is regarded as a suitable analog to future climate change. In this study, the PETM climate is investigated using the Community Climate System Model (CCSM3) with atmospheric CO₂ concentrations of 4×, 8×, and 16× the...
Published in: | Journal of Climate |
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Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Meteorological Society
2010
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Subjects: | |
Online Access: | http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-000-460 https://doi.org/10.1175/2009JCLI3113.1 |
Summary: | The Paleocene-Eocene Thermal Maximum (PETM; 55 Ma) is of particular interest since it is regarded as a suitable analog to future climate change. In this study, the PETM climate is investigated using the Community Climate System Model (CCSM3) with atmospheric CO₂ concentrations of 4×, 8×, and 16× the preindustrial value. Simulated climate change from 4× to 8× atmospheric CO₂ concentration, possibly corresponding to an environmental precursor of the PETM event, leads to a warming of the North Atlantic Ocean Intermediate-Water masses, thus lowering the critical depth for methane hydrate destabilization by 500 m. A further increase from 8× to 16×CO₂, analogous to a possible massive methane hydrate release, results in global oceanic warming and stratification. The increase in the radiative surface warming, especially at high latitudes, is partially offset by a decrease in the ocean heat transport due to a reduced overturning circulation. Surface temperature values simulated in the 16×CO₂ PETM run represent the closest match to surface temperature reconstructions from proxies for this period. Simulated PETM precipitation, characterized by a slight northward shift of the intertropical convergence zone, increases at higher CO₂ concentrations, especially for the northern midlatitudes as well as the high latitudes in both hemispheres. Data-inferred precipitation values and gradients for North America and Spain, for instance, are in good agreement with the 16×CO₂ simulation. Increasing atmospheric CO₂ concentrations might also have favored the release of terrestrial methane through warmer and wetter conditions over land, thus reinforcing the greenhouse gas concentration increase. |
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