Premium
A late medieval warm period in the Southern Ocean as a delayed response to external forcing?
Author(s) -
Goosse H.,
MassonDelmotte V.,
Renssen H.,
Delmotte M.,
Fichefet T.,
Morgan V.,
van Ommen T.,
Khim B. K.,
Stenni B.
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl019140
Subject(s) - northern hemisphere , upwelling , climatology , southern hemisphere , forcing (mathematics) , lag , ocean current , period (music) , oceanography , ocean general circulation model , geology , thermohaline circulation , sea surface temperature , climate change , environmental science , general circulation model , computer network , physics , computer science , acoustics
On the basis of long simulations performed with a three‐dimensional climate model, we propose an interhemispheric climate lag mechanism, involving the long‐term memory of deepwater masses. Warm anomalies, formed in the North Atlantic when warm conditions prevail at surface, are transported by the deep ocean circulation towards the Southern Ocean. There, the heat is released because of large scale upwelling, maintaining warm conditions and inducing a lagged response of about 150 years compared to the Northern Hemisphere. Model results and observations covering the first half of the second millenium suggest a delay between the temperature evolution in the Northern Hemisphere and in the Southern Ocean. The mechanism described here provides a reasonable hypothesis to explain such an interhemipsheric lag.