Variability of Arctic climate and sea ice over the past millennium: implications for ice cap mass balance

Project summary

Core retrieval

Correlation & chronology

Proxy climate

Proxy sea ice & biological activity

Atmospheric circulation

Facilities

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This study of Arctic climate system dynamics will be based on the recovery, analysis, and interpretation of two long ice cores from the northern summit of Prince of Wales (PoW) Icefield, Ellesmere Island, Nunavut. Ice cores from PoW will be used to investigate the timescale of natural variability in the core records (Venegas and Mysak, 2000) and the relationships between these proxy records of climate, sea ice, biological activity and glacier mass balance and major atmospheric modes such as the Arctic and North Atlantic Oscillations (AO/NAO) (Hurrell, 1995; Thompson and Wallace, 1998; Vinther et al., 2003; D'Arrigo et al., 2003).

We will also address such questions as whether the Little Ice Age (LIA) and Medieval Warm Period (MWP) are recognizable in the POW ice core record, and whether the magnitude of late twentieth century climate warming in the region exceeds that of other warm periods in the 1000-year record (Overpeck et al., 1997; Fisher, 2002; Mann et al. 2003; Soon and Baliunas; 2003).

The covariance between proxy records of climate, sea ice, and marine biological productivity will also be investigated to determine whether or not warm (cold) periods are associated with reduced (increased) sea ice extent and concentration, increased (decreased) accumulation on ice caps, and changes in biological productivity.

We will test the somewhat controversial hypothesis that the response of glacier mass balance to climate variability is a function of the time scale of variability. At short time scales (years to a few decades), it is clear that glacier mass balance variability in the Arctic is directly proportional to variations in summer temperature and surface melt (Koerner, 2002). This leads to the prediction that climate warming will lead to more negative mass balance and glacier shrinkage. It has, however, been argued that, at longer time scales, a sea ice mediated temperature/precipitation feedback that allows glaciers to grow as sea ice shrinks and atmospheric moisture transport increases may become important (Gildor and Tziperman, 2000, 2001). It is critical to determine whether or not such a feedback does occur in high latitudes because it has significant implications for the response of Arctic glaciers to anthropogenic climate warming, with direct impacts on global sea level.