Chapter 6 - Greenlandian Stage (Early Holocene, 11.7–8.2 ka)

Abstract

The Greenlandian Stage (Early Holocene) was a period of substantial climate change in Europe, essentially a transition towards a warmer climate punctuated by recurrent cold anomalies. The Holocene onset is defined in Greenland ice-core proxies, which reveal warming over Greenland of >10°C and accompanying atmospheric circulation changes which occurred within a few decades. Marine records reveal a rapid sea-surface warming of 5°C–10°C, strongest in the high latitudes of the northern North Atlantic and weaker in the Mediterranean Sea. Terrestrial records from northern and central Europe indicate warming on the order of 4°C–6°C at the Holocene onset with the greatest amplitude of temperature change in the mid-latitudes (50–60°N) and along the Atlantic margins of Western Europe. In southern Europe, warming at the Holocene onset was of lower magnitude (<4°C), and a subsequent shift towards a more humid climate was typically delayed by a millennium or longer. Across Europe, rapid warming was generally sustained during the first two millennia of the Holocene. Against this trajectory, several centennial-scale cooling anomalies occurred, which include the 11.4ka event (Preboreal Oscillation), the 10.3 and 9.3ka events and finally the 8.2ka event, which defines the end of the Greenlandian Stage. These events reveal a typical cooling signal over Greenland and the European continent (varying in magnitude from <1°C to as much as −4°C depending on the event and location). They also display spatial contrasts in hydrological impacts, typically with wetter conditions at central European latitudes and drier conditions in northern and southern Europe, reflecting the changes in the strength and position of the atmospheric westerlies. Forcing of these events is attributed to the disruption of North Atlantic deepwater formation by freshwater pulses to the North Atlantic from melting ice sheets, while the role of solar and volcanic forcing remains an open scientific question.