ARCUS 14th Annual Meeting and Arctic Forum 2002

Quantifying Pan-Arctic Environmental Change

James E. Overland^1
1Pacific Marine Environmental Lab./NOAA, 7600 Sand Point Way NE, Seattle, WA, 98115, USA, Phone 206.526.6795, Fax 206.526.6795, overland@pmel.noaa.gov

The Arctic has undergone major temperature swings over the last 100 years. Over the past three decades, demonstrable pan-Arctic changes have occurred in many components of the physical and biological system. The areal coverage of sea ice has diminished, and sea level pressures in the central Arctic have decreased, resulting in a shift of wind and heat flux patterns. Warmer surface temperatures are observed in northern Europe during winter and Alaska and northwest Canada during spring, there is an increase in the frequency of years with cold temperature anomalies in the lower stratosphere over high latitudes, and permafrost temperatures have risen in Siberia and Alaska with increased erosion. Satellite estimates of "greening" have increased over both the eastern and western hemispheres, with longer growing seasons and changes in the character of the tundra. The influence of warm Atlantic water in the Arctic Ocean is becoming more widespread and intense, with implications for the stability of the water column. These changes are robust, and many other biological and physical changes are suggested: increases in cod in the Barents and shrimp off of southern Greenland, increases in calf survival for some caribou populations in North America, and declines and redistributions of marine mammal populations, although causes for these changes are less certain.

Extrapolation of atmospheric and sea ice records from the last 100 years implies a reversal of present trends in 2000–2030, while IPCC climate models imply a continuation of the current course. At present, neither evidence nor understanding is available to unequivocally distinguish between these scenarios. A promising method for future detection of change is to use a multivariate approach. Biological and terrestrial variables are often better indicators of decadal change than physical variables because they integrate over the large meteorological and oceanographic interannual and intraseasonal variability. A data collection for 1965 – 1995 of 85 variables representing 7 data types shows broad pan-Arctic covariability for a shift in ecosystems near 1989. Understanding biocomplexity is an important factor in developing an Arctic change detection system as extremes in the physical environment lasting one or two years can precipitate biological/ecosystem changes that last several decades.

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