[Music]
Narrator: On September 18th 2019, satellites observed that
Arctic sea ice had reached its annual low.
This year's sea ice minimum is effectively tied for the second lowest on record.
And while sea ice grows and shrinks with the seasons,
2019 continues the downward trend of the extent.
Nathan Kurtz: The trends we’ve been seeing
with the sea ice minimum have just been a decrease.
So, in the 70’s since the modern record began tracking to today,
there is variation from year to year, but it’s really just a
a downward trend. Narrator: Satellite observations show that Arctic sea ice
is not only shrinking in extent, it is also becoming younger
and thiner. That means less and less ice survives
the annual melt. Kurtz: The Artic has actually warmed a lot more than
the globe at a whole. There is something called Artic amplification, which means
that the temperatures in the Arctic have warmed about 2 – 3 times
the global average.
Narrator: A major cause of this warming is due to the loss of the reflectivity - or albedo – of the sea ice.
Snow-covered sea ice has a high albedo. This helps keep the
sun’s energy from being absorbed by a dark ocean.
But when sea ice melts, it loses some of that reflectivity.
And without the sea ice cover, the ocean will absorb most
of the sun’s energy.
This creates a feedback loop that leads to more melting and warming in the Arctic.
Kurtz: We care about sea ice for a variety of reasons.
One being is because it does have an impact on things like our weather and our climate.
Because of the albedo effect if you decrease the amount of sea ice
you start warming up the Arctic, and when you start warming up the Arctic
you start changing the circulating of the jet stream which brings
weather to us here in the mid latitudes.
Other reasons why we care about sea ice, Arctic sea ice in particular,
Because we’ve such big changes due to warming
melting ice, it is a good visual to show that, yes, the climate
Is changing and it is because of warming.
Narrator: NASA continues to monitor these changes to the Arctic so that we may get a better
understanding of what we can expect in the future. [Music]