Glacier shrinkage is causing a “green transition”

Microbial life will flourish in mountain streams because of ongoing glacier shrinkage. This is what a team of scientists from EPFL and Charles University, Prague, report in a paper published in Nature Geoscience. Their observations are based on samples collected from 154 glacier-fed streams worldwide as part of the EPFL-led Vanishing Glaciers project, which is funded by the NOMIS Foundation.

Glacier-fed streams are murky, raging torrents in the summer. Large quantities of glacial meltwater churn up rocks and sediment, allowing very little light to reach the streambed, while freezing temperatures and snow in other seasons provide little opportunity for a rich microbiome to develop. But, as glaciers shrink under the effects of global warming, the volume of water originating from glaciers is declining. That means the streams are becoming warmer, calmer, and clearer, giving algae and other microorganisms an opportunity to become abundant and to contribute more to local carbon and nutrient cycles. “We’re witnessing a process of profound change at the level of the microbiome in these ecosystems – nothing short of a ‘green transition’ because of the increased primary production,” says Tom Battin, a full professor at EPFL’s River Ecosystems Laboratory (RIVER).