Past and future response of the North Atlantic warming hole to anthropogenic forcings
- CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France
Abstract. Most of the North Atlantic ocean has warmed over the last decades, except a region located over the subpolar gyre, known as the North Atlantic warming hole, where sea surface temperature has in contrast decreased. Previous assessments have attributed part of this cooling to the anthropogenic forcings (aerosols and greenhouse gases) modulated by decadal internal variability. Here I use an innovative and proven statistical method which combines climate models and observations to confirm the anthropogenic role in the WH cooling, and to provide estimates of the contribution of a set of given external forcings. Furthermore, the method is able to reduce the uncertainty in the WH temperature over the historical period, but also in the future, with a decrease of 65 % in the short term, up to 50 % in the long term. A model evaluation validates the reliability of the obtained projections. In particular, the projections associated with a strong temperature increase over the warming hole are now excluded from the likely range obtained after applying the method.
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