Large amounts of bacteria could be released as the world’s glaciers melt due to climate change, scientists have warned.
Potentially harmful pathogens are among the thousands of microbes that can leach into rivers and lakes.
Researchers at Aberystwyth University said their study highlighted the need to act quickly to curb global warming.
They studied meltwater from eight glaciers across Europe and North America and two sites in Greenland.
Glaciers are large bodies of slowly moving ice that have formed over hundreds or thousands of years. As the planet warms, they are melting at an alarming rate – causing sea levels to rise.
The team at Aberystwyth University estimated that more than 100,000 tonnes of microbes, such as bacteria, could be released into the environment over the next 80 years – a number comparable to all the cells in the human body on Earth.
Microbiologist Dr Arwyn Edwards said the study clearly showed for the first time the “large scale” of microorganisms living on the surface or locked within the Earth’s glaciers.
“The number of microbes released depends closely on how fast the glaciers melt, and therefore how much we continue to warm the planet,” he said.
The team’s calculations are based on a “moderate” warming scenario, developed by the IPCC, an international panel of climate experts.
This would raise global temperatures by 2C to 3C on average by 2100.
As the flow of microbes into rivers, lakes, fjords and seas increases, there could be “significant” impacts to water quality, Dr Edwards explained.
But this would be followed within decades by the microbial tap being turned off, as the glaciers completely disappear.
He said: “Globally there are a significant 200,000 glacial meltwater fed catchments and some of these are very sensitive environments that are not well developed in terms of carbon and organic nutrients.
“In other cases there is a lot of economic activity and billions of people whose livelihoods depend on water that ultimately comes from those glaciers.
“We think of glaciers as a vast store of frozen water but the main lesson from this research is that they are also ecosystems in their own right.”
Thousands of different microorganisms are found growing on glaciers, or stored inside them, he said, some of which may be harmful to humans.
“The risk is probably very small, but it requires careful assessment.”
Glaciologist Dr Tristram Irvine-Fynn said more research was needed: “Over the coming years, the forecast ‘peak water’ from the world’s mountain glaciers means we will need to improve our understanding of the state and fate of improve ecosystem.
“With a better understanding of that picture, we could better predict the effects of climate change on glacial surfaces and catchment biogeochemistry.”
The Aberystwyth academics’ findings are published in the journal Nature Communications Earth & Environment this month.