Cyanobacteria—photosynthetic microbes that live in meltwater—are likely growing more abundant here, thanks to warmer temperatures and decreased cloud cover. When these bacteria come into contact with sediments (largely made of quartz) on a glacier, they make the particles clump together to form balls 91 times their original size. So instead of the little particles washing away in meltwater, they start accumulating in streams atop glaciers, which are more formally known as supraglacial streams.
And in case you haven’t been reading the news: Melting glaciers are bad .
These microscopic bacteria could have big implications for the planet. Greenland’s ice sheet covers over 650,000 square miles, and if it melted entirely, global sea levels would rise 24 feet, according to NASA. That’s not plausible anytime soon, but NASA further estimates that Greenland lost 3.8 trillion tons of ice between 1992 and 2018, contributing 0.4 inches to global sea level rise in that time.To be clear, the presence of bacteria on Greenland’s ice sheet is nothing new. Microbes are intertwined with sediments that either make their way up the ice from exposed land around the base of the glaciers, or blow in from farther away. As this dust accumulates on the glacier, it forms what scientists call cryoconite holes: The darker sediment absorbs the sun’s energy, heating the ice to melt away a divot, which you can see below.