caa a22 4500 605472351 CHVBK 20210128100337.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00382-015-2561-x doi (NATIONALLICENCE)springer-10.1007/s00382-015-2561-x Indications for a North Atlantic ocean circulation regime shift at the onset of the Little Ice Age [Elektronische Daten] [C.-F. Schleussner, D. Divine, J. Donges, A. Miettinen, R. Donner] A prominent characteristic of the reconstructed Northern Hemisphere temperature signal over the last millennium is the transition from the Medieval Climate Anomaly to the Little Ice Age (LIA). Here we report indications for a non-linear regime shift in the North Atlantic ocean circulation at the onset of the LIA. Specifically, we apply a novel statistical test based on horizontal visibility graphs to two ocean sediment August sea-surface temperature records from the Norwegian Sea and the central subpolar basin and find robust indications of time-irreversibility in both records during the LIA onset. Despite a basin-wide cooling trend, we report an anomalous warming in the central subpolar basin during the LIA that is reproduced in ensemble simulations with the climatemodel of intermediate complexity CLIMBER-3 $$\alpha$$ α as a result of a non-linear regime shift in the subpolar North Atlantic ocean circulation. The identified volcanically triggered non-linear transition in the model simulations provides a plausible explanation for the signatures of time-irreversibility found in the ocean sediment records. Our findings indicate a potential multi-stability of the North Atlantic ocean circulation and its importance for regional climate change on centennial time scales. Springer-Verlag Berlin Heidelberg, 2015 Little Ice Age nationallicence Volcanic forcing nationallicence Last millennium nationallicence Horizontal visibility graphs nationallicence Time series irreversibility nationallicence Marine sediments nationallicence Tipping element nationallicence Schleussner C.-F Climate Analytics, Berlin, Germany aut Divine D. Norwegian Polar Institute, Fram Centre, Tromsø, Norway aut Donges J. Potsdam Institute for Climate Impact Research, Potsdam, Germany aut Miettinen A. Norwegian Polar Institute, Fram Centre, Tromsø, Norway aut Donner R. Potsdam Institute for Climate Impact Research, Potsdam, Germany aut Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3623-3633 0930-7575 45:11-12<3623 2015 45 382 https://doi.org/10.1007/s00382-015-2561-x text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-015-2561-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Schleussner C.-F Climate Analytics, Berlin, Germany aut NATIONALLICENCE 700 1- Divine D. Norwegian Polar Institute, Fram Centre, Tromsø, Norway aut NATIONALLICENCE 700 1- Donges J. Potsdam Institute for Climate Impact Research, Potsdam, Germany aut NATIONALLICENCE 700 1- Miettinen A. Norwegian Polar Institute, Fram Centre, Tromsø, Norway aut NATIONALLICENCE 700 1- Donner R. Potsdam Institute for Climate Impact Research, Potsdam, Germany aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3623-3633 0930-7575 45:11-12<3623 2015 45 382