Holocene Climate Evolution of the North Atlantic Ocean and the Nordic Seas — a Synthesis of New Results

Synthesis of oceanic records shows that the surface waters of the North Atlantic and the Nordic Seas have been modulated by the strength of the Northern Hemisphere insolation during the Holocene. This is manifested by the early Holocene optimum temperatures and the general cooling trend of the surface ocean since then. However, the duration of this optimum decreased both towards the north and towards the margins of the Nordic Seas suggesting that some regions of the oceans being more sensitive to climatic forcings than others. There is increasing evidence that superimposed on the late Holocene cooling trend there is also a higher frequency (albeit subtle) variability of multi-decadal and centennial time scales in the ocean. The magnitude of this variability is in the order of a few degrees. At the moment the underlying mechanisms for this variability remains as a topic of debate.