Research press release


Nature Geoscience

Microbes increase glacier melt on Alaskan icefield



Roman Dialたちは今回、氷河上で、氷河の雪の異なる領域に栄養素と水を加える実験を行った。その結果、擾乱を加えない対照地域と比較して、水を加えた場合には1.5倍の藻類が見られること、栄養素を含めた場合はほぼ4倍の藻類が見られることが分かった。著者たちは、地形全体の積雪を人工衛星データを用いて見積もり、雪を赤くする藻類は融解をおよそ17%増加させることを示している。藻類に覆われた赤い雪の地域はより多くの融解水を生成するので、藻類をより成長させて、氷河のさらなる融解を促すフィードバックをもたらす可能性がある。

Snow-dwelling microbes on an Alaskan ice field could substantially accelerate glacier melt by making the surface darker and decreasing its reflectivity, which in turn encourages the growth of more algae, according to a study published online in Nature Geoscience this week.

Although fresh snow reflects the majority of the incoming energy from the Sun, impurities such as black carbon and dust darken the surface and reduce the reflected energy. This dirty snow increases glacial melting as the darker snow surface warms more easily. The specialized algae living on glaciers have a similar effect as they change the colour of the snow surface to red, making it darker than unaffected snow.

Roman Dial and colleagues carried out experiments on the glacier in which they added nutrients and water to different areas of glacial snow. Compared to a control, which was left undisturbed, they find one and a half times more algae when water is added and almost four times more algae when nutrients are included. Using data from satellites to estimate snowmelt across the landscape, they show that red-snow algae increased melting by about 17%. As the areas of algae-covered red snow generate more meltwater, this could lead to a feedback of more algal growth and glacial melting.

doi: 10.1038/ngeo3027


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