Sea ice is basically frozen seawater that lies on the sea
surface due to its reduced density. A high proportion of sea ice on Earth is
located in the two areas where the climate dominated by more cool temperatures
– the Polar Regions. A certain amount of influence is provided by factors like
atmospheric and ocean circulations, temperatures and other climatic components
on nature of the sea ice in a particular area. As seasonal variations take
place throughout the year, sea ice undergoes changes. Several years of studies
carried out to observe these changes have aided scientists in developing graphs
and trends on variables like sea ice extent, volume, thickness and so on.
The Arctic region, which is the polar region of the Earth’s
Northern hemisphere, is almost entirely landlocked. This differs from the
Antarctic region where Antarctica is a landmass surrounded by oceans. The
National Snow and Ice Data Center (NSIDC) provided a very
useful comparison between sea ice in the Arctic and the Antarctic. To put
it simply, sea ice formed in the Arctic is less mobile, and therefore
accumulates and during seasons when the ice is meant to melt, results in the
formation of older ice sheets that become thicker over the years. There are
also other disparities that are taken into account, such as the symmetry of the
ice extent, snow thickness, solar energy absorption and so on.
The average Arctic sea ice extent throughout the year is about
15 million km2 during winter and approximately 7 million km2 during
the summer months. Due to this phenomenon the Arctic sea ice has some
significance to the Earth’s oceans and climate and that
current issues pertaining to how it is changing could prove to be quite serious.
In March 2016, NASA
reported that the Arctic sea ice maximum that tends to be some time between
February and April hit a new low this year. It was recorded that the maximum
sea ice extent of 14.52 million km2 was reached on March 24. The satellite
records that produce this information also showed that 13 of the lowest sea ice
maximums have occurred in the past 13 years. This can be coupled with current
increased global temperatures, both in the atmosphere and the ocean. Warmer
seas cause more difficulty in the formation of sea ice. And at the same time,
less sea ice would mean that less sunlight is reflected back, reducing the
albedo, which ties with a certain amount of climate regulation.
Another
NASA article also displays some footage of satellite images showing how
older, stronger and thicker sea ice has started melting away. This older sea
ice, which is referred to as the ‘bulwark of sea ice’
by Walt Meier, one of NASA’s sea ice researchers, has become
more susceptible to melting during the summer months due to warmer climates.
This is a cause for concern as Meier also states that this increases the
possibility of an iceless Arctic during the warmer months.
As stated previously, Arctic sea ice helps to regulate the
climate of the Earth, by controlling the albedo. A change in the sea ice extent
seems to be fully capable of causing a positive feedback in other factors,
potentially snowballing (pun not intended) into a more severe and drastic
consequence. In a paper written by Rothrock et
al., the effects of the thinning of sea ice seem to relate back to increase
in heat fluxes.
This change also inevitably affects living beings in the
region. For instance, several journals and magazines reported that, between the
years 2006 and 2013, 80000 reindeer in Russia starved to death due to shrinking
Arctic sea ice. Their food supply had been cut due to thick layers of ice
formed by more warm-weather precipitations like rain, causing the snow to
harden on land. Thinning of the sea ice caused an increase in rainfall due to
more open water available to be vapourised.
If attempts to reverse these effects are not taken, it will
not be long before more consequences radiate globally. A warming climate has
caused changes in the sea ice extent, which in turn also accounts for further
changes in the climate. Anthropogenic warming is occurring at a rate higher
than it has ever been, so it is only natural to think that the effects of this
change will take shape well before we even expect it to.
Some links to the articles on the reindeer:
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