Joint Seminar: Can Arctic warm the Earth?

Confidence in future climate predictions is based upon ability of climate models to simulate the 20th century global temperature changes. Multi-model IPCC ensemble perfectly reproduces the 1970-1999 temperature trend, although it tends to underestimate a ratio between polar and equator warming. The model ensemble, however, fails to capture the early 20th century warming anomaly, suggesting a possibility of an internal multi-decadal climate fluctuation. Strong multi-decadal climate variability coherent with global temperature deviations from secular warming trend is manifested in the northern North Atlantic (NA) sea surface temperatures. However, the mechanism of the strong Atlantic multi-decadal variability (AMV) impact on global climate is not clear. Here we show that local turbulent heat flux anomalies related to the AMV in the NA (north of 40N) and Atlantic sector of the Arctic may produce a global-scale warming with a pattern being very similar to the observed trends and strong equator-pole warming contrast. The atmospheric heating in the Arctic due to sea ice reduction is responsible for more than a half of the global temperature changes. The remote impact is due to atmospheric circulation response by reduced northward meridional heat transport and strengthened zonal stationary wave related to ocean-continental heating contrast. The results imply that internal low-frequency ocean dynamics, presumably related to the meridional overturning circulation in the NA, may explain the major part of the ECW and roughly a half of the warming since 1970s in the Northern hemisphere.




13:30 h


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Vladimir Semenov, IFM GEOMAR, Kiel


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