Climate Response at the Paleocene–Eocene Thermal Maximum to Greenhouse Gas Forcing—A Model Study with CCSM3
| Autor: | Cindy J. Shellito, Cornelia Winguth, Christine A. Shields, Arne M.E. Winguth |
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| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Journal of Climate. 23:2562-2584 |
| ISSN: | 1520-0442 0894-8755 |
| DOI: | 10.1175/2009jcli3113.1 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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