Risk of rapid North Atlantic cooling greater than previously estimated

February 15 2017 Science Daily  full article here

The possibility of major climate change in the Atlantic region has long been recognized and has even been the subject of a Hollywood movie: The Day After Tomorrow. To evaluate the risk of such climate change, researchers ….developed a new algorithm to analyze the 40 climate models considered by the latest report from the Intergovernmental Panel on Climate Change (IPCC). Their findings raise the probability of rapid North Atlantic cooling during this century to nearly 50%. Nature Communications publishes their work on February 15, 2017….

Current climate models all foresee a slowing of the meridional overturning circulation (MOC) — the phenomenon behind the familiar Gulf Stream, which carries warmth from Florida to European shores — that could lead to a dramatic, unprecedented disruption of the climate system. In 2013, …the IPCC judged that this slowdown would occur gradually over a long period of time… that fast cooling of the North Atlantic during this century was unlikely.

….The Labrador Sea is host to a convection system ultimately feeding into the ocean-wide MOC. The temperatures of its surface waters plummet in the winter, increasing their density and causing them to sink. This displaces deep waters, which bring their heat with them as they rise to the surface, preventing the formation of ice caps. To investigate this phenomenon in greater detail, the researchers developed an algorithm able to detect quick sea surface temperature variations. Their number crunching revealed that 7 of the 40 climate models they were studying predicted total shutdown of convection, leading to abrupt cooling of the Labrador Sea: by 2-3 °C over less than 10 years. This in turn would drastically lower North Atlantic coastal temperatures……

Giovanni Sgubin, Didier Swingedouw, Sybren Drijfhout, Yannick Mary, Amine Bennabi. Abrupt cooling over the North Atlantic in modern climate models. Nature Communications, 2017; 8 DOI: 10.1038/ncomms14375