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Climate emergency: feedback loops - albedo
Climate change is setting off dangerous feedback loops at the Poles. The melting of Arctic ice and snow decreases Earth’s ability to reflect the sun’s rays, leading to further heating and melting of ice and snow. In Antarctica, the warmer climate is melting ice sheets, leading to raised sea levels, which melts ice sheets further in an amplifying loop.
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- At5:40, it predicts that the Arctic ice will be 100% gone by the end of the century. Does that mean that the world will end in 2100?(0 votes)
- No. Coastal cities or islands will be flooded, but the overall sea rise isn't enough to end the world yet.
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Video transcript
[Narrator] For tens of thousands of years, the delicate balance
of Earth's climate has allowed human life
on our planet to thrive. Today, that equilibrium is at risk, as one of the most important
cooling mechanisms, the albedo effect, or Earth's reflectivity,
is threatened. At Earth's poles, snow and ice reflect up
to 85% of the sun's rays away from the surface
and back into space, helping to keep the planet
from becoming too hot. But over the past few decades, this natural mirror
has begun to break down as fossil fuel emissions
raise temperatures, melt snow and ice cover,
and reduce the planet's albedo. As the planet loses
its ability to reflect sunlight, a dangerous warming feedback loop
is triggered. The most alarming change
is happening in the Far North, where the temperature rise
is causing the snow cover and sea ice
to rapidly disappear. Don Perovich is a sea ice geophysicist
at Dartmouth College. For the past thirty years,
he's been documenting big changes in the Arctic. [Perovich] There's always been
this annual cycle– the ice grows usually, say,
for nine or ten months of the year, and then melts
for a couple of months. What's changing now is the timing. The melting is starting earlier,
the freezing is starting later. We have much less coverage
every month of the year, particularly at the end of summer. [Narrator] Global warming from human-caused
emissions of heat-trapping gases– carbon dioxide, methane,
nitrous oxide, and others– is increasing
the temperature in the Arctic two to three times faster
than the rest of the planet. Warming is then amplified
by the loss of albedo as the reflective ice
and snow disappear, exposing the dark ocean underneath. [Perovich] Say it's April
and we're flying above the Arctic and we look down
at the sea ice cover. It's covered by snow,
it's bright and it's white. Now, summer comes, that snow melts,
you get more open ocean. You're absorbing much more heat. Instead of reflecting 85%,
you're absorbing 90%. And so, you're replacing
one of the best natural reflectors, snow, with one of the worst,
the open ocean. [Narrator] Now, instead of reflecting
the sunlight, the ocean absorbs it,
heats up and melts more ice, exposing more dark ocean, which absorbs more sunlight
in an amplifying cycle. [Woodwell] As those darker waters warm, they emit carbon dioxide and water vapor,
warming things further. So, there are several aspects to this feedback
in the Arctic problem, which are truly frightening. [Narrator] Scientists have been
measuring Arctic sea ice since long before satellites
began taking reliable measurements in the early 1970s. By the end of that decade, the climate models predicted
sea ice would begin to disappear with the increase of heat-trapping gases
in the atmosphere. Marika Holland is a climate modeler from
the National Center for Atmospheric Research. [Holland] So, our first climate models
were developed in the 1970s. Those models,
even in their simplicity, predicted that with rising greenhouse gases
in the atmosphere, we would see dramatic sea ice loss
in the Arctic, and the Arctic warming
would be amplified relative to the globe. [Narrator] And as measurement techniques improved, scientists were alarmed to discover
just how much ice had been lost. [Francis] The volume has decreased by 75%
in only 40 years. It's just a breathtaking change
in a very short time. We call it the New Arctic now because it's so different
from what it used to be. The ice now is mainly consisting
of what we call first-year ice, which is just ice that's formed
in that one winter, and most of it doesn't survive
through the summer. It all melts. [Narrator] Studies suggest that around
a quarter of global warming is caused by the loss
of this sea ice. But if you factor in the melting of snow cover
on the surrounding land, together they account
for an estimated 40% loss in the planet's reflectivity. [Holland] The snow cover over land
is very bright and very reflective. It reflects an enormous amount
of the sunlight away from the surface, just like the sea ice cover does. And we are seeing reductions
in the aerial coverage of snow over the land, just like we're seeing reductions
in the aerial coverage of sea ice. [Narrator] With feedback loops
amplifying the warming, the landscape of the Arctic
will change irrevocably. [Holland] So our climate model projections suggest that we will lose
the Arctic sea ice cover in the summer months altogether
by the end of this century. If we continue to increase
greenhouse gases in the atmosphere through the burning
of fossil fuels, we ultimately will get to a state
where we lose the winter sea ice as well. [Narrator] A sobering prediction considering
that ice has covered the Arctic Ocean for more than 2.5 million years. And the warming
happening in the Arctic isn't staying in the Arctic. The air there is mixing
into the global atmosphere elsewhere on Earth and raising
global temperatures. [Holland] The Arctic plays a very central role
in Earth's climate. Even if you just lose
sea ice cover in the Arctic, the tropics will feel
that enhanced warming. [Narrator] This means amplification of problems
the climate crisis is already causing: crops suffering,
food prices going up, wet areas becoming wetter,
dry areas becoming drier. And as the climate warms,
it kicks in another feedback loop, set in motion by the melting
of massive glacial ice sheets. In the past 30 years, the loss of ice on the Greenland ice sheet
has increased six-fold, leading to a rise in sea level. As the ocean rises, the higher, warmer water
melts more land ice, raising sea levels further, and melting even more ice
in a vicious cycle. In the South Pole, the increased temperature is thawing
the miles-thick Antarctic ice sheets that have been accumulating on land
for over 40 million years. [Holland] Loss of ice
over the Antarctic continent doesn't have as much of an albedo feedback
because it's so thick. But as that ice enters the ocean,
it causes sea level to rise. [Narrator] If both Greenland and Antarctica's
glacial ice shelves were to melt, sea levels would potentially rise
by more than a hundred feet. This resulting destruction
to coastlines would uproot millions of people
around the world. It would also mean the ice sheets
would reach a tipping point, taking thousands of years to recover. [Holland] If we lose an enormous amount of ice
from the land, reestablishing that
is a very long timescale issue. [Narrator] And if we continue
with business as usual, the warming in the Arctic
will cause the feedback loops at both poles
to spin out of control. [Holland] The models predict
if we continue on the path we're on, that the Arctic will experience
very dramatic changes and that those changes will reverberate
throughout the system, the human system, the biological system,
the socioeconomic system. [Narrator] With every country
contributing to the problem, each now needs
to be part of the solution. [Woodwell] That requires managing
the world in such a way that we do not exploit
carbon compounds and dump the waste
into the atmosphere. [Emanuel] The emission of greenhouse gases
is an example of a market failure, one business enterprise passing on
the real cost of doing business to people who aren't party
to that business, that is, most of the rest of us. [Narrator] In every sector
of the economy we have the technology
and knowledge to move toward sources of energy
that do not produce heat-trapping gases. What we need is the will. We must stop adding fossil fuels
to the atmosphere, which are warming the planet,
melting the ice and snow cover, and lowering the reflectivity
of the Arctic. If we cut emissions, stop deforestation,
and regreen the Earth, we can slow, halt,
or even reverse the feedback loop, lower temperatures,
regenerate snow and ice cover, increase reflectivity,
and heal our planet. [Perovich] You have all this heat
in the ocean; it would take a few years of cold temperatures
to get rid of it. But once you did,
you would get ice to form again. [Emanuel] The most important thing
citizens can do is to educate themselves
on this issue, and vote for politicians
who take this problem seriously, and have good ideas
for how to solve it. [Perovich] I'm optimistic by nature, and I become more optimistic
when I see so many people that realize there's a problem. The pessimistic part of me says, the longer we wait,
the harder it gets. It's time to act.