Why the Arctic is climate change's canary in the coal mine - William Chapman
The area surrounding the North Pole
may seem like a frozen and desolate
environment where nothing ever changes.
But it is actually a complex
and finely balanced natural system,
and its extreme location
makes it vulnerable to feedback processes
that can magnify even tiny changes
in the atmosphere.
In fact, scientists often describe
the Arctic as the canary in the coal mine
when it comes to predicting the impact
of climate change.
One major type of climate feedback
involves reflectivity.
White surfaces, like snow and ice,
are very effective at reflecting
the sun's energy back into space,
while darker land and water surfaces
absorb much more incoming sunlight.
When the Arctic warms just a little,
some of the snow and ice melts,
exposing the ground and ocean underneath.
The increased heat absorbed by
these surfaces causes even more melting,
and so on.
And although the current situation
in the Arctic follows the warming pattern,
the opposite is also possible.
A small drop in temperatures
would cause more freezing,
increasing the amount
of reflective snow and ice.
This would result in less sunlight
being absorbed,
and lead to a cycle of cooling,
as in previous ice ages.
Arctic sea ice is also responsible
for another feedback mechanism
through insulation.
By forming a layer on the ocean's surface,
the ice acts as a buffer between
the frigid arctic air
and the relatively
warmer water underneath.
But when it thins, breaks,
or melts in any spot,
heat escapes from the ocean,
warming the atmosphere
and causing more ice to melt in turn.
Both of these are examples
of positive feedback loops,
not because they do something good,
but because the initial change
is amplified in the same direction.
A negative feedback loop,
on the other hand,
is when the initial change
leads to effects
that work in the opposite direction.
Melting ice also causes
a type of negative feedback
by releasing moisture into the atmosphere.
This increases the amount and thickness
of clouds present,
which can cool the atmosphere
by blocking more sunlight.
But this negative feedback loop
is short-lived,
due to the brief Arctic summers.
For the rest of the year,
when sunlight is scarce,
the increased moisture and clouds
actually warm the surface
by trapping the Earth's heat,
turning the feedback loop positive
for all but a couple of months.
While negative feedback loops
encourage stability
by pushing a system towards equilibrium,
positive feedback loops destabilize it
by enabling larger and larger deviations.
And the recently increased impact
of positive feedbacks
may have consequences
far beyond the Arctic.
On a warming planet,
these feedbacks ensure that the North Pole
warms at a faster rate than the equator.
The reduced temperature differences
between the two regions
may lead to slower jet stream winds
and less linear atmospheric circulation
in the middle latitudes,
where most of the world's
population lives.
Many scientists are concerned
that shifts in weather patterns
will last longer and be more extreme,
with short term fluctuations becoming
persistent cold snaps,
heat waves, droughts and floods.
So the Arctic sensitivity doesn't just
serve as an early warning alarm
for climate change
for the rest of the planet.
Its feedback loops can affect us
in much more direct and immediate ways.
As climate scientists often warn,
what happens in the Arctic
doesn't always stay in the Arctic.
