WEBVTT

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The area surrounding the North Pole

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may seem like a frozen and desolate
environment where nothing ever changes.

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But it is actually a complex 
and finely balanced natural system,

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and its extreme location 
makes it vulnerable to feedback processes

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that can magnify even tiny changes
in the atmosphere.

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In fact, scientists often describe 
the Arctic as the canary in the coal mine

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when it comes to predicting the impact
of climate change.

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One major type of climate feedback
involves reflectivity.

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White surfaces, like snow and ice,

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are very effective at reflecting
the sun's energy back into space,

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while darker land and water surfaces
absorb much more incoming sunlight.

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When the Arctic warms just a little,
some of the snow and ice melts,

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exposing the ground and ocean underneath.

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The increased heat absorbed by
these surfaces causes even more melting,

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and so on.

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And although the current situation
in the Arctic follows the warming pattern,

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the opposite is also possible.

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A small drop in temperatures
would cause more freezing,

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increasing the amount 
of reflective snow and ice.

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This would result in less sunlight 
being absorbed,

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and lead to a cycle of cooling,
as in previous ice ages.

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Arctic sea ice is also responsible
for another feedback mechanism

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through insulation.

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By forming a layer on the ocean's surface,

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the ice acts as a buffer between
the frigid arctic air

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and the relatively 
warmer water underneath.

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But when it thins, breaks, 
or melts in any spot,

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heat escapes from the ocean,

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warming the atmosphere 
and causing more ice to melt in turn.

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Both of these are examples
of positive feedback loops,

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not because they do something good,

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but because the initial change 
is amplified in the same direction.

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A negative feedback loop,
on the other hand,

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is when the initial change
leads to effects

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that work in the opposite direction.

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Melting ice also causes 
a type of negative feedback

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by releasing moisture into the atmosphere.

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This increases the amount and thickness
of clouds present,

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which can cool the atmosphere
by blocking more sunlight.

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But this negative feedback loop
is short-lived,

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due to the brief Arctic summers.

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For the rest of the year, 
when sunlight is scarce,

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the increased moisture and clouds

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actually warm the surface
by trapping the Earth's heat,

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turning the feedback loop positive
for all but a couple of months.

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While negative feedback loops
encourage stability

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by pushing a system towards equilibrium,

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positive feedback loops destabilize it
by enabling larger and larger deviations.

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And the recently increased impact
of positive feedbacks

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may have consequences 
far beyond the Arctic.

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On a warming planet,

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these feedbacks ensure that the North Pole
warms at a faster rate than the equator.

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The reduced temperature differences
between the two regions

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may lead to slower jet stream winds

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and less linear atmospheric circulation
in the middle latitudes,

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where most of the world's 
population lives.

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Many scientists are concerned
that shifts in weather patterns

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will last longer and be more extreme,

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with short term fluctuations becoming
persistent cold snaps,

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heat waves, droughts and floods.

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So the Arctic sensitivity doesn't just
serve as an early warning alarm

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for climate change 
for the rest of the planet.

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Its feedback loops can affect us
in much more direct and immediate ways.

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As climate scientists often warn,

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what happens in the Arctic
doesn't always stay in the Arctic.