Publication Date:
2017-04-04
Description:
The Middle Eocene Climatic Optimum (MECO) is an enigmatic warming event that
represents an abrupt reversal in long-term cooling through the Eocene. In order to further
assess the timing and nature of this event, we have assembled stable isotope and calcium
carbonate concentration records from multiple Deep Sea Drilling Project and Ocean
Drilling Program sites for the time interval between ~43 and 38 Ma. Revised stratigraphy
at several sites and compilation of δ18O records place peak warming during the MECO
event at 40.0 Ma (Chron C18n.2n). The identification of the δ18O excursion at sites in
different geographic regions indicates that the climatic effects of this event were globally
extensive. The total duration of the MECO event is estimated at ~500 kyr, with peak
warming lasting 〈100 kyr. Assuming minimal glaciation in the late middle Eocene, ~4 to
6ºC total warming of both surface and deep waters is estimated during the MECO at the
study sites. Maximum warming at ~40.0 Ma also coincided with a world-wide decline in
carbonate accumulation at sites below 3000 m depth, reflecting a temporary shoaling of the
calcite compensation depth. The synchroneity of deep-water acidification and globally
extensive warming makes a persuasive argument that the MECO event was linked to a
transient increase in atmospheric pCO2. The results of this study confirm previous reports
of significant climatic instability during the middle Eocene. Furthermore, the direct link
between warming and changes in the carbonate chemistry of the deep ocean provides
strong evidence that changes in greenhouse gas concentrations exerted a primary control
on short-term climate variability during this critical period of Eocene climate evolution.
Description:
Published
Description:
PA2207
Description:
2.2. Laboratorio di paleomagnetismo
Description:
3.8. Geofisica per l'ambiente
Description:
JCR Journal
Description:
partially_open
Keywords:
ODP
;
Eocene
;
stable isotope
;
abrupt/rapid climate change
;
02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate
;
03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
;
04. Solid Earth::04.04. Geology::04.04.02. Geochronology
;
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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