an important aspect of our world. One that is essential to
maintaining a stable climate and, by extension, the health of modern
civilizations. Today, due to a continued warming of the globe, every
form of frozen water — be it frozen water locked in glaciers, snow,
or sea ice — is under threat. And we are almost daily reminded of
new losses coming from these needed collections of cold.
ice area [upper right], extent [upper left], and volume [lower
graphs] have all seen very serious declines that have now lasted for
a full year. Since reflective sea ice is an important regulator of
global and regional climates, the impacts of such a considerable loss
is likely to be both long-term and wide-ranging. Image source: Global
sea ice area and extent have now ranged between 2 and 3 million
square kilometers below the 38 year average for about a year now.
That’s a region of sea ice larger than Greenland which has been
removed from the face of the Earth now for the better part of four
seasons. Global sea ice volume losses are now in the range of 12,000
cubic kilometers — each cubic kilometer roughly equal to a
moderate-sized mountain. These are very considerable losses. But
perhaps more ominous than the losses themselves is the fact that they
seem to be sticking around —
locking in a permanent warming-related-change to the Earth System,
its weather and environment.
be clear, there are some things that sea ice loss does not directly
impact. And the first of which is sea level rise. Because sea ice
already floats on the surface of the ocean and because it already
displaces water, melting sea ice does little to change the level of
the ocean surface directly.
very informative video describing ice albedo feedback. We do not,
however, support some of the video’s sponsors who, unfortunately,
appear to be ubiquitous.)
said, there are many things that sea ice loss does affect. And the
first is global temperature balance. Sea ice serves as both a
reflective shield that throws back the sun’s heat during summer and
as an insulator that locks warmer ocean waters below during
a significant portion of the global sea ice, as we have done, and
you’ll end up with oceans that both draw in more heat during the
warmer months and bleed out more stored ocean heat into the
atmosphere during the winter.
heat will be both stored and delivered exactly where it can do the
most harm — in the polar regions. And, as a result, recently
ice-liberated oceans will warm more rapidly in areas that are
directly adjacent or close to the very large glaciers covering
Greenland and Antarctica. As such, though melting sea ice has no
direct, immediate impact on sea level rise, it can create an added
pressure for the loss of land-bound and sea-fronting glaciers that
will raise ocean levels if they melt.
sea ice loss feedbacks produce complex and far-reaching impacts to
the entire Arctic system. Image source: National
regions also face considerable added heat pressure to permafrost,
boreal forests, and other carbon stores as a result of Arctic Ocean
albedo feedbacks due to sea ice loss. In addition, warm pools of
ocean water in the far north will aid in further
destabilizing already-altered weather patterns.
So sea ice loss is likely to continue to result in a worsening of the
Jet Stream excursions that have already contributed to extreme
weather — particularly in the Northern Hemisphere.
perhaps the most concerning impact of sea ice loss is an alteration
to seasonal temperature exchange. More heat absorbed by oceans during
summer and then ventilated back to the atmosphere during fall and
winter will tend to result in a lag in global cooling into the fall
season even as winter will tend to warm.
roll-back of sea ice results in much warmer temperatures over nearby
permafrost zones. This week, 81.5 F [27.5 C] temperatures are
predicted for parts of the Yamal Peninsula — a region that has
recently drawn attention for its newly discovered methane blow-holes.
Image source: Earth
a lag enhanced by sea ice loss is arguably already in play in the
Northern Hemisphere — where increasing rates of heat exchange
between the tropics and middle latitudes and the pole have already
been observed. However, if Southern Hemisphere sea ice remains
reduced, a similar heat exchange and polar amplification pattern is
likely to begin setting up there as well.
upshot is that the observed considerable loss of global sea ice
coverage is likely to produce harmful or disruptive feedbacks in the
Earth’s climate system in the near term. Stresses to the other
frozen systems of the world will tend to increase as a result.
Extreme weather events are at risk of worsening. Rates of polar
warming could escalate. And disruptions to traditional seasonality
will tend to become more apparent.