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Connecting changing ocean circulation with changing climate

November 28th, 2012


Key Findings

  • Without ocean circulation changes, the patterns of heat and carbon storage are quite similar. This contrasts with the fully interactive simulation, where the patterns of heat and carbon storage differ due to redistribution of the ocean’s heat content by circulation changes.
  • Redistribution of ocean heat content induces a shift of surface heat uptake from low latitudes to high latitudes.
  • Because the climate system is more sensitive at higher latitudes, the heat uptake shift to high latitudes increases its cooling effect. Therefore ocean circulation changes act as a negative feedback on climate change, reducing the warming, especially at high latitudes.
  • The overall heat and carbon uptake are not significantly affected by ocean circulation changes.

Michael Winton, Stephen Griffies, Bonnie Samuels, Jorge Sarmiento and Thomas Froelicher. Journal: Journal of Climate. DOI: 10.1175/JCLI-D-12-00296.1

Summary

Our capability to observe ocean changes has improved dramatically over the past two decades, motivating interest in how these observations can be used to constrain climate change simulations. Projections of future surface climate change and ocean circulation change are both very uncertain. This research shows that circulation changes are important to the surface climate change and we describe a mechanism for the connection.

We examined the role of changing ocean circulation in climate change, by performing a climate change simulation where ocean circulation changes are disallowed, for comparison to the fully interactive simulation. Our results suggest that observations of ocean circulation can provide a useful constraint on surface climate projections.

The study makes use of a novel technique for assessing the role of ocean circulation change in climate change. However, only one model is used to make this assessment and it is known to be a model with a very responsive circulation. Other models might show less impact of ocean circulation changes.

Sea surface temperature change without (left) and with (right) ocean circulation changes.
Sea surface temperature change without (left) and with (right) ocean circulation changes.