Weather Extremes During the Paleocene Eocene Thermal Maximum
Abstract
The Paleocene Eocene Thermal Maximum was a time of elevated levels of atmospheric carbon dioxide (> 1500ppm) and extremely warm surface temperatures extending from the tropics to polar regions (~20 C). Latitudinal proxies of surface temperatures also indicate a lower equator to pole temperature gradient. These mean climatic conditions have important implications for shifts in atmospheric dynamics and high temporal frequency atmospheric phenomena, i.e. weather events, for the PETM. Such shifts are further supported by independent proxy information indicating the presence of a more active atmospheric water cycle due to the warm, moist mean climate of the PETM. To date, attention has been focused on modeling the mean climate state for different periods of the Eocene. More recently, climate model simulations have been carried out to look at extreme weather events during the PETM, however, many of these studies typically explicitly resolve spatial dynamical scales of a few hundred kilometers which may limit their ability to study extreme weather. Here, for the first time, we present results from a suite of climate simulations using the atmospheric component of the CESM1.2 run at a global, 25-kilometer resolution. The high-resolution atmospheric simulations employ sea-surface temperature distributions obtained from a set of fully coupled CESM1.2 simulations of the PETM and pre-PETM conditions. The high resolution of PETM and pre-PETM simulations also include companion simulations for orbital forcings representative of either maximum or minimum Northern Hemisphere insolation. We present a summary of results from these various simulations highlighting how the atmospheric water cycle operates under elevated atmospheric carbon dioxide and a low equator to pole thermal gradient. In particular, we consider statistics of extremes in heat waves, precipitation and river runoff. We will also present results on hurricane activity in terms of intensity, trajectories and most poleward extent of hurricane activity. These phenomena are of importance, since proxy data suggest the presence of strong coastal precipitation events during the PETM. We conclude our presentation by comparing the PETM extremes weather statistics with those from an RCP8.5 2100 climate simulation.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP24C..03K
- Keywords:
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- 9604 Cenozoic;
- INFORMATION RELATED TO GEOLOGIC TIME;
- 4914 Continental climate records;
- PALEOCEANOGRAPHY;
- 4928 Global climate models;
- PALEOCEANOGRAPHY;
- 4954 Sea surface temperature;
- PALEOCEANOGRAPHY