Abrupt transitions can be of several types and affect the environment in different ways. Theoretical indications of instabilities can be found in a broad spectrum of climate models (energy balance models, a thermohaline model of deep-water circulation, atmospheric general circulation models, and coupled ocean-atmosphere models). There is a growing body of theoretical and empirical support for the concept of instabilities in the climate system, and indications that abrupt climate change may in some cases contribute to abrupt extinctions. PMID:28198383Ībrupt climate change and extinction events
Thus, due to systematic model biases, the CMIP5 ensemble as a whole underestimates the chance of future abrupt SPG cooling, entailing crucial implications for observation and adaptation policy. This event occurs in 45.5% of the 11 models best able to simulate the observed SPG stratification. Uncertainty in projections is associated with the models' varying capability in simulating the present-day SPG stratification, whose realistic reproduction appears a necessary condition for the onset of a convection collapse. Contrary to the long-term SPG warming trend evidenced by most of the models, 17.5% of the models (7/40) project a rapid SPG cooling, consistent with a collapse of the local deep-ocean convection. Here we assess the risk of future abrupt SPG cooling in 40 climate models from the fifth Coupled Model Intercomparison Project (CMIP5). This region even experienced a rapid cooling around 1970, raising a debate over its potential reoccurrence. Observations over the 20th century evidence no long-term warming in the subpolar North Atlantic (SPG). Sgubin, Giovanni Swingedouw, Didier Drijfhout, Sybren Mary, Yannick Bennabi, Amine Abrupt cooling over the North Atlantic in modern climate models
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