
Figure 1 – Comparison of proxy records from Kråkenes (western Norway) and Meerfelder Maar (MFM) (western Germany). Ti count rate is a proxy for glacier melting within the catchment and shows abrupt increase in count rate 20 yr after the Vedde Ash. Glacier melting was probably due to a climatic amelioration associated with stronger westerly winds. In MFM the same record is used as a proxy for wind-driven diatom blooms with rapid decrease in count rate 100 yr before the Vedde Ash. Records are plotted together with the NGRIP ice cores δ18O proxy (Rasmussen et al. 2006) to show the temporal extent of the Younger Dryas in Greenland. The tephra horizon has been used to estimate the time lag between climate changes recorded at MFM and Kråkenes, respectively, associated with the same atmospheric phenomenon, i.e. a northward diversion of the north Atlantic Polar Front. Figure modified after Lane et al. (2013).
Our ability to predict future climate changes relies heavily on the goodness of physical climate models to capture short-term, regional to local expressions of atmospheric circulation dynamics. This diagnostic ability is aided by knowledge on paleoclimate scenarios. Indeed, we can examine well-dated and highly-resolved proxy-based climate reconstructions to understand past atmospheric dynamics and to investigate the direction in time and space of physical processes associated with rapid climate shifts.
The Younger Dryas (YD) (12850-11670 yr BP) is the last major climatic oscillation in the North Atlantic region and constitutes an ideal natural laboratory to study past rapid shifts of the climate system. As such, the YD was a period of abrupt cooling and pervasive environmental change across Europe, commonly ascribed to major oceanographic changes in the North Atlantic domain (Broecker, 1998; McManus et al. 2004). Continue reading →