Science Special Section: International Polar Year

An iceberg calved from a glacier floats in the Jacobshavn fjord in southwest Greenland. A new CU-Boulder study indicates Greenland continues to lose ice mass, and the rate of loss is accelerating.
[Photo courtesy of Konrad Steffen, CU-Boulder]

In coordination with the launch of the International Polar Year, a two-year international effort to study the Arctic and Antarctic, the 16 March issue of Science features a special section exploring the health and influence of Earth's coldest climates.

The four-article series paints a picture of the polar processes that influence our planet's ecological and biochemical cycles, focusing on ice sheet mass balance, sea-level rise, and atmospheric chemistry.

In a review of more than two decades of climate studies, researchers Kathy S. Law and Andreas Stohl assert that the Arctic, once believed to be pristine, is now being polluted from the lower latitudes of the Northern Hemisphere. The authors document an "arctic haze," a mixture of sulfate, organic matter, and other contaminants originating from northern Eurasian pollution, ship emissions, and summertime forest fires.

A second study reviewing 15 years of research estimates that Greenland and Antarctica are losing a combined mass of 125 gigatons a year—enough to raise sea level 0.35 millimeters per year on top of the present annual increase of 3 millimeters. In the article, authors Andrew Shepherd and Duncan Wingham praise satellite-based sensors for supplying data on the changing ices sheets and call for more meteorological and ice core measurements to increase confidence in forecasting models.

In a third article, authors Mark C. Serreze and colleagues note that while climate models vary, most show that Arctic ice will continue to shrink, and half of the models predict that September 2100 could be an Arctic ice-free month. The impacts of such loss, the authors believe, could include reduced rainfall in the American West, increased rainfall in western and southern Europe in winter, and intensified mid-latitude storm tracks.

In a Perspective, David G. Vaughan and Robert Arthern contend that substantial uncertainties about the processes at an ice sheet's base and its sea margin hamper scientists' understanding of ice sheet behavior and the role the ice sheets of might play in future sea-level rise. At the ice sheet's base, the authors point out, interactions between water flow, friction, sediment deformation and heat flow become intertwined in complex ways.

Evelyn Brown and Benjamin Somers

16 March 2007