[Rockhounds] Sun-Loving Bacteria May Be Accelerating Glacial Melting

[Kreigh Tomaszewski]

THE BUTTERFLY EFFECT describes how a tiny input, like the flapping of an
insect’s delicate wings in South America, can kick off a series of
snowballing events, like the formation of a tornado in North America. At
least, that’s the idea in the mathematical world of chaos theory. While
atmospheric scientists will tell you
<https://gizmodo.com/is-the-butterfly-effect-real-1835800111> that it’s not
particularly likely that a butterfly has such powers—no doubt a relief to
conscientious butterflies everywhere—the effect in general is real:
Seemingly inconsequential events can trigger a cascade of knock-on effects
that grow in size and significance. On the Greenland ice sheet, scientists
say they’ve found an agent of such change that’s far smaller than a
butterfly, but whose proliferation could have far more consequence than a
tornado.

Cyanobacteria—photosynthetic microbes that live in meltwater—are likely
growing more abundant here, thanks to warmer temperatures and decreased
cloud cover <https://advances.sciencemag.org/content/3/6/e1700584>. 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.

“This sediment is very dark, and therefore absorbs a lot of sunlight,” says
Rutgers University hydrologist Sasha Leidman, lead author on a recent paper
<https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL088444> describing
the findings in the journal *Geophysical Research Letters*. “What the paper
found is that this sediment would not be there without the fact that
there's bacteria growing in the sediment and clumping it together so it
can't be washed away.” More dark grit, then, could be absorbing more of the
sun’s energy, and accelerating the melting of the ice sheet.

https://www.wired.com/story/sun-loving-bacteria-may-be-accelerating-glacial-melting/