“The ice
sheet below tells a tale of disintegration,” writes Eli Kintisch of Science as the helicopter of scientists
hovers over Greenland’s interior. “Long, roughly parallel cracks score the
surface, formed by water and pressure; impossibly blue lakes of meltwater fill
depressions; and veiny networks of azure streams meander west, flowing to the
edge of the ice sheet and eventually out to sea.”
Greenland’s
ice sheet is the second largest ice mass in the world (after Antarctica). It
covers about 10% of the Earths surface and holds three quarters of the world’s
freshwater. The sheet contains enough water to raise sea levels by at least 20
feet. Glaciers flowing from the Greenland Ice Sheet have been retreating since
the 1990s. Melt rate of the ice sheet is accelerating, losing 8,000 tons per
second.
In 2016,
ice melt started early and spread inland fast. By April, 12% of the ice sheet’s
surface was melting. In an average year the melt doesn’t reach 10% until June,
writes Kintisch about this growing “liquid fury.” Between 2011 and 2014,
satellite data and modelling suggested that “70% of the annual 269 billion tons
of snow and ice shed by Greenland was lost through surface melt, not calving
[which itself had surged recently].” This added surface melt has doubled
Greenland’s contribution to global sea level rise. “Things are happening a lot
faster than we expected,” said geophysicist Isabella Velicogna of the
University of California, Irvine.
What does
this mean? “Greenland holds the equivalent of more than 7 metres of sea level
rise in its thick mantle of ice,” writes Kintisch. You don’t need to do the
math to understand the significance.
The Arctic
is warming twice as fast as the rest of the world. But warmer moist air is not
solely responsible for this accelerated melt. Microbes and algae are thriving
on the wet surface, producing pigments that boost the ice’s absorption of solar
energy. Soot and dust blowing in from lower latitudes darken the ice with the
same effect.
Kintisch
writes of the scientists’ mission called “Black and Bloom” (referring to the
soot and the algae, respectively) to study how these organisms are affecting
the behaviour of the melting ice sheet. “We’re driven by curiosity,” says team
leader Martyn Tranter, a biogeochemist at the University of Bristol, “but also
the fear that all this new biology may accelerate global sea level rise.”
Scientists
have found that dust and soot from European factories and Canadian wildfires
have over the centuries been trapped and concentrated at the melting edge of
the ice sheet. The scientists suspect that algae and bacteria play a sinister
role in exacerbating the melt in places where the ice surface has become pocked
with holes of crystal clear meltwater underlain by a spot of black sludge—known
as cryoconite—at the bottom. Cryoconite is living bacteria that captures solar
energy; it keeps the water from freezing. Brown-pigmented algal extremophiles
that thrive in the freezethaw cycles also stain massive areas of ice. This
growing meltwater ecosystem may drive an ever-accelerating melt.
As the
Arctic warms, melt episodes are likely to “occur much more frequently in the
future,” says Dirk van As of the Geological Survey of Denmark and Greenland in
Copenhagen.
Climate
scientist Marco Tedesco of Columbia University published a study that gave
evidence for retreating Arctic sea ice disrupting the polar jet stream, causing
weather systems to mender more slowly from west to east. What this means is
unclear; but it confirms that extent and complexity of ecosystem changes on a
global scale. Scientists also documented the exponential (nonlinear) character
of the change. What this means is that change will compound itself as systems
cascade.
Acknowledging
the challenges of working in the growing meltwaters of a giant ice sheet, the
Black and Bloom researchers also felt wonder at the transforming landscape. Jim
McQuaid of the University of Leeds said, “Each evening we marveled as the sun
went low, enjoying the fact that we were somewhere no one else had been, and
would never be again, because of the melt.”
Nina Munteanu is an ecologist and internationally published author of award-nominated speculative novels, short stories and non-fiction. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s recent book is the bilingual “La natura dell’acqua / The Way of Water” (Mincione Edizioni, Rome). Her latest “Water Is…” is currently an Amazon Bestseller and NY Times ‘year in reading’ choice of Margaret Atwood.
