McMurdo Dry Valleys

The McMurdo Dry Valleys form a strikingly exposed landscape in Victoria Land, near McMurdo Sound. Unlike the familiar image of a continent buried under continuous snow, much of this terrain is bare rock, soil or gravel. The valleys are described as a cold desert, but they are not devoid of water: glaciers, snow patches, ice-covered lakes and short-lived streams shape the ecosystem. Conditions vary across the valleys, and wind, sunlight, temperature and local topography influence where snow and ice persist.

In summer, meltwater from glaciers feeds streams that flow for a limited part of the season, connecting slopes and lake basins. Long-term research in Taylor Valley studies these flows alongside the chemistry and ecology of lakes such as Fryxell, Hoare and Bonney. The lakes remain covered by ice, and their physical and chemical conditions help determine which organisms can live in them. Microbial mats and other microscopic communities are important components of the valleys' streams, soils and lakes.

The McMurdo Dry Valleys were selected in 1992 as a site in the United States National Science Foundation's Long Term Ecological Research network. Researchers combine measurements of weather, glaciers, streamflow, lake conditions and soils to understand how the system changes over time. Because meltwater connects separate parts of the landscape, a change in temperature or snow cover can affect runoff, lake levels and the organisms that depend on water.

The valleys were once regarded as exceptionally stable, but comparisons of surface-elevation measurements from 2001 with later surveys found thawing permafrost, thinning glaciers and melting ground ice in parts of the region. The findings indicate that change can occur even in this very cold setting. They do not mean every valley or glacier is changing at the same rate: local conditions and the period measured matter when interpreting observations.