Arctic microbes may be causing glaciers to melt faster, as scientists from Aberystwyth University have found that these microbes may be causing melting that is currently not accounted for in climate change models.
In this latest study, the researchers focused on a grainy substance that's found on top of the surface of Arctic ice. Known as cryoconite, this soil-like materials is made of dust and industrial soot that's glued together by photosynthetic bacteria.
Arctic ice usually reflects about 60 percent of the sunlight that hits it. This is known as its albedo level. However, cryoconite can decrease the albedo of ice to about 20 percent. This means more of the energy is absorbed by the ice and thus melts it faster.
Interestingly, the granules are made by bacteria. When the ice melts, it creates small, water-filled holes. The granules regulate the depth and shape of these holes to maximize their exposure to sunlight. In the summer, cryoconite holes pockmark the surface of the Greenland ice sheet; as the climate warms, though, the expanse that these cryoconite holes cover is expanding.
"If we recognize ice surfaces as a living landscape we can see that the microbes themselves are able to change the glacial surface," head researcher Arwyn Edwards said. "It's only recently that we've begun to understand that these cryoconite holes are dynamic, changing in size and shape. Microbes are capable of ecosystem engineering and respond to changes in their environment all the time. As the biologically productive areas of glaciers and ice sheets expand due to climate change, these microbial processes can influence their melting more and more. In the long term, this contributes to the loss of glacier habitats, and the unique microbial biodiversity living on them."
Current models that look at glacier melt actually don't effectively account for the impacts of microbial growth. This is particularly important to note as this growth spreads due to warming temperatures. Without proper models that account for this growth, researchers may have a difficult time calculate the rates of melt for this glaciers.
The findings reveal a bit more about glacier melt, and also show that more attention needs to be paid to the microbial growth that occurs on the surfaces of ice.
The research will be presented Wednesday at the Microbiology Society's Annual Conference in Liverpool.
