Fast-melting glaciers release a staggering amount of bacteria into rivers and streams, which could transform icy ecosystems, warns scientists.
In a study of glacial run off from ten sites across the Northern Hemisphere, the researchers estimated that continued global warming over the next 80 years could release hundreds of thousands of tonnes of bacteria into downstream of receding glaciers.
“The loss of ice from glaciers outside Greenland and Antarctica is acceleratingand is expected to peak within the next 50 year. This meltwater discharge will have profound effects upon the microbial productivity, biogeochemical cycles, and biodiversity and function4 of glacier-fed ecosystems. Of particular importance is the organic carbon (OC) that these glacial meltwaters deliver to downstream environments, supplementing these locations with bioavailable,” the researchers said.
Led by glacial hydrologist Ian Stevens of Aarhus University in Denmark, the team sampled surface meltwater from ten glaciers across the Northern Hemisphere: in the European Alps, Greenland, Svalbard, and the far reaches of the Canadian Arctic.
Glaciers are masses of ice creeping ever so slowly toward the sea, carving out mountainous valleys as they go. Yet there is more to the flows than frozen water, with minerals, gases, and organic materials trapped on a one-way slide that could take tens of thousands to millions of years to terminate.
Studying the contents of glaciers is like opening the door to another time in history. Microbes entombed inside them could be a rich source of useful, new compounds, such as antibiotics. However, the researchers behind this new study say melting glaciers are releasing tonnes upon tonnes of bacteria faster than scientists can possibly catalog them, the researchers noted.
Finding on average tens of thousands of microbes in each milliliter of water, they estimate that more than a hundred thousand tonnes of bacteria could get into glacial meltwaters over the next 80 years, not including the glaciers in the Himalaya Hindu Kush region of Asia.
That’s equivalent to 650,000 tonnes of carbon released per year into rivers, lakes, fjords, and oceans across the Northern Hemisphere, though it depends on how fast glaciers melt and how fast we curb emissions.
Under a ‘middle of the road’ emissions scenario – that would still see global temperatures rise between 2 and 3 °C – masses of bacteria in meltwater can peak within decades before declining or potentially disappearing entirely as glaciers recede, the researchers found.
Microbes in meltwater can fertilize downstream ecosystems, but these may be sensitive environments or catchments used by communities that depend on glacial runoff as a water source.
Bacteria and algae found in icy environments usually contain pigments to shield themselves from damaging sunlight. But these pigments, in absorbing solar energy, could add to warming that is already accelerating glacial ice loss.
The authors published tyhe study in Communications Earth & Environment.