Greenland (GISP2) ice core and historical indicators of complex North Atlantic climate changes during the fourteenth century

Abstract

The paper uses Greenland GISP2 ice core data together with historical documentary information to investigate the nature of climate changes that took place between AD 1270 and 1450 across the North Atlantic region. Detailed Deuterium and deuterium excess time series resolved to c. 8—10 samples per year are used to reconstruct relative changes in Greenland air temperature and past changes in sea surface temperature across the western North Atlantic. The data show that sea surface temperatures during the late thirteenth century and the majority of the fourteenth century were characterized by relatively high-amplitude warming and cooling `events'. These changes preceded a marked reduction in the amplitude of the sea surface temperature changes c. 30—40 years before the well-known change in Northern Hemisphere tropospheric circulation characterized by a marked increase in regional storminess that started between c. AD 1400 and 1420. The time interval between AD 1270 and 1450 also appears over Greenland to have featured several short-lived phases of marked air temperature lowering that were rarely ever equalled during succeeding centuries. We believe that the climate changes described here are of considerable importance in understanding climate dynamics of the North Atlantic region since they took place at a time when the North Atlantic Oscillation (NAO) may have been weak. The results also show that the marked change in atmospheric circulation coincident with a significant increase in North Atlantic storminess at c. AD 1400—1420, possibly the biggest such change in the Holocene, took place after the strong perturbations in North Atlantic sea surface temperature (both warming and cooling) described here as well as after several episodes of air temperature lowering over Greenland.

Relative sea-level change in Greenland during the last 700 yrs and ice sheet response to the Little Ice Age

“…This was followed by a relatively warm interval and a second minimum at c. 1850 A.D. (Dahl-Jensen et al, 1998;Johnsen et al, 2001). Ice core accumulation data suggest little evidence for persistent changes during the period after 1200 A.D. (Andresen et al, 2004) although Deuterium and Na ++ records all point towards a significant change in moisture source after c. 1400 A.D. that may record a strengthening of meridional circulation (Dawson et al, 2007;Hoffmann et al, 2001;Kreutz et al, 1997;Mayewski et al, 1993).…”

Tracking climate variability in the western Mediterranean during the Late Holocene: a multiproxy approach

“…These climatic oscillations have been described in Greenland ice cores (e.g. O'Brien et al, 1995;Dawson et al, 2007), and in North Atlantic (e.g. Bond et al, 1997;Bianchi and McCave, 1999), Mediterranean (e.g.…”

“…Willard et al, 2005;Jalut et al, 2009) and tree rings (e.g. Esper et al, 2002;Moberg et al, 2005). Nevertheless, the overall lack of agreement about the worldwide distribution, precise timing, amplitude or cause of these fluctuations underlines the need for additional regional records to reconstruct climate change (e.g.…”

The historic record of cold spells in Ireland

“…Blackford and Chambers (1995) were able to demonstrate this relationship using peat humidification records from Ireland, but noted no evidence of the Wolf Minimum or post-1900 relationship with solar variability. In the former case it is suggested that the North Atlantic climate, as evidenced by major reduction in the NAO prior to AD 1420, may have been operating very differently (Dawson et al 2007). Given the relationship between the NAO and AO it is likely the AO would also operate very differently in this time period.…”