THRESHOLDS - Thresholds for destabilizing thermohaline circulation and ocean carbon cycling in a warmer world

Project Department: Uni Research Climate (groups: Biogeochemistry, Biogeochemical Oceanography) period: 01.06.16 - 31.12.19

About the project

How stable is the Atlantic Ocean circulation? Can today's overturning circulation that acts like a heat pump to the Nordic regions change rapidly when the North Atlantic warms? What could trigger sudden changes and what would the climate consequences be? These are the questions being addressed in the THRESHOLDS project.

Using deep marine sediment sequences recovered by the International Ocean Discovery Program, together with computer models, THRESHOLDS will determine just how the ocean circulation varied in the past when the North Atlantic was warmer than present and the Greenland ice sheet was melting. New evidence is emerging that suggests the ocean circulation varied much more than we previously thought during warm climate periods. For a long time it was thought that circulation was stable during warm interglacial periods. Recent studies analyzing the sediment records in
greater detail reveal that we were missing large changes that occurred suddenly and may have lasted for centuries. These circulation changes were linked to sudden climate shifts and resulted in large changes in the ocean distribution of carbon. If they occurred today they could alter sea level, marine productivity, and climate and rainfall patterns over vast regions of the globe. However, the extent and details of these impacts remain poorly understood.

THRESHOLDS will use detailed sediment records to determine under what conditions these sudden ocean changes were triggered in
the past and whether there are thresholds or early warning signals for an imminent change. Models will then be used to better understand these past changes and how they can inform us about potential future ocean changes
and their impacts.
 

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cp: 2019-04-22 12:16:49