16 September 2017

Amplified North Atlantic Warming in the Late Pliocene by Changes in Arctic Gateways

Science

We analyze experiments with a climate model and a new reconstruction of mid-Piacenzian paleogeography that has the Bering Strait and Canadian Arctic Archipelago Straits closed. Closure of these small Arctic gateways strengthens the Atlantic Meridional Overturning Circulation, by inhibiting freshwater transport from the Pacific to the Arctic Ocean and from the Arctic Ocean to the Labrador Sea, and improves the agreements between simulated and  proxy-indicated warm sea surface temperatures in the North Atlantic.

Impact

Under previous reconstructions of late Pliocene boundary conditions, climate models fail to reproduce the higher sea surface temperatures in the North Atlantic. 

Summary

If this holds as the inherent uncertainties in the proxies are reduced and better sampled, this would call into question whether climate models being used for future projections can adequately simulate the feedbacks that produce polar amplification in high CO2 worlds. 

Contact
Aixue Hu
National Center for Atmospheric Research (NCAR)
Publications
Jahn, A. "Amplified North Atlantic Warming in the Late Pliocene by Changes in Arctic Gateways." Geophysical Research Letters 44, 957-964 (2017). [10.1002/2016gl071805].