Bistability of the Atlantic overturning circulation in a global climate model and links to ocean freshwater transport

摘要: The possibility of a rapid collapse in the strength Atlantic meridional overturning circulation (AMOC), with associated impacts on climate, has long been recognized. suggested basis for this risk is existence two stable regimes AMOC (‘on’ and ‘off’), such bistable behaviour identified range simplified climate models. However, up to now, no state-of-the-art atmosphere-ocean coupled global model (AOGCM) exhibited behaviour, leading interpretation that more than simpler models indicate. Here we demonstrate bistability response freshwater perturbations FAMOUS AOGCM - most complex exhibit date. results also support recent suggestions direction net transport at southern boundary by may be useful physical indicator bistability. We present new estimates from ocean reanalyses which suggest currently regime, although large uncertainties. More accurate observational constraints, an improved understanding quantity, could help narrow uncertainty future evolution assess collapse.