|
|
Variability of Arctic climate and sea ice over the past millennium: implications for ice cap mass balance |
Why the Arctic?
|
Analysis of the isotopic and chemical stratigraphy of ice cores can generate continuous proxy records of air temperature, net accumulation, summer melt, sea ice extent and marine biological productivity (Fisher and Koerner, 2003). In addition, due to the long-distance transport of marine aerosols, Arctic ice cores contain information about sea ice conditions throughout much of the Arctic region (Curran. 2003). As multiple proxy records are generated within a single stratigraphy it is possible to undertake detailed examination of the covariance of the various environmental conditions they reflect. The real world conditions represented in the ice core can be explored by comparing proxy data of recent decades with climate reanalysis data (NCEP/NCAR and ERA 40) generated using global circulation models. These models interpolate measured data from limited points in space and time to give a more complete representation of global climate conditions over the period of instrumental records. A particular advantage of using ice core analysis is that snow accumulates sufficiently rapidly to enable this information to be obtained at annual or sub-annual resolution from the present day into past millennia. Thus, Arctic ice cores produce records that can be used to investigate the interactions between climate, sea ice, and ice cap mass balance on time scales longer than the few decades provided by instrumental records (Fischer, 2001; Kahl, Galbraith and Martinez, 1999; Legrand and Mayewski, 1997; Isaksson et. al., 2005). This is especially important as it offers long-term context against which recent climate trends can be assessed. |