1
00:00:06,761 --> 00:00:09,132
The area surrounding the North Pole

2
00:00:09,132 --> 00:00:14,052
may seem like a frozen and desolate
environment where nothing ever changes.

3
00:00:14,052 --> 00:00:19,006
But it is actually a complex 
and finely balanced natural system,

4
00:00:19,006 --> 00:00:23,306
and its extreme location 
makes it vulnerable to feedback processes

5
00:00:23,306 --> 00:00:27,068
that can magnify even tiny changes
in the atmosphere.

6
00:00:27,068 --> 00:00:32,282
In fact, scientists often describe 
the Arctic as the canary in the coal mine

7
00:00:32,282 --> 00:00:36,260
when it comes to predicting the impact
of climate change.

8
00:00:36,260 --> 00:00:39,703
One major type of climate feedback
involves reflectivity.

9
00:00:39,703 --> 00:00:41,946
White surfaces, like snow and ice,

10
00:00:41,946 --> 00:00:46,027
are very effective at reflecting
the sun's energy back into space,

11
00:00:46,027 --> 00:00:51,109
while darker land and water surfaces
absorb much more incoming sunlight.

12
00:00:51,109 --> 00:00:55,094
When the Arctic warms just a little,
some of the snow and ice melts,

13
00:00:55,094 --> 00:00:58,111
exposing the ground and ocean underneath.

14
00:00:58,111 --> 00:01:01,966
The increased heat absorbed by
these surfaces causes even more melting,

15
00:01:01,966 --> 00:01:03,605
and so on.

16
00:01:03,605 --> 00:01:07,111
And although the current situation
in the Arctic follows the warming pattern,

17
00:01:07,111 --> 00:01:09,365
the opposite is also possible.

18
00:01:09,365 --> 00:01:12,607
A small drop in temperatures
would cause more freezing,

19
00:01:12,607 --> 00:01:15,942
increasing the amount 
of reflective snow and ice.

20
00:01:15,942 --> 00:01:18,484
This would result in less sunlight 
being absorbed,

21
00:01:18,484 --> 00:01:22,757
and lead to a cycle of cooling,
as in previous ice ages.

22
00:01:22,757 --> 00:01:26,634
Arctic sea ice is also responsible
for another feedback mechanism

23
00:01:26,634 --> 00:01:28,271
through insulation.

24
00:01:28,271 --> 00:01:30,206
By forming a layer on the ocean's surface,

25
00:01:30,206 --> 00:01:33,446
the ice acts as a buffer between
the frigid arctic air

26
00:01:33,446 --> 00:01:36,432
and the relatively 
warmer water underneath.

27
00:01:36,432 --> 00:01:39,450
But when it thins, breaks, 
or melts in any spot,

28
00:01:39,450 --> 00:01:41,642
heat escapes from the ocean,

29
00:01:41,642 --> 00:01:45,720
warming the atmosphere 
and causing more ice to melt in turn.

30
00:01:45,720 --> 00:01:48,961
Both of these are examples
of positive feedback loops,

31
00:01:48,961 --> 00:01:50,791
not because they do something good,

32
00:01:50,791 --> 00:01:54,905
but because the initial change 
is amplified in the same direction.

33
00:01:54,905 --> 00:01:57,250
A negative feedback loop,
on the other hand,

34
00:01:57,250 --> 00:01:59,701
is when the initial change
leads to effects

35
00:01:59,701 --> 00:02:02,289
that work in the opposite direction.

36
00:02:02,289 --> 00:02:05,276
Melting ice also causes 
a type of negative feedback

37
00:02:05,276 --> 00:02:08,367
by releasing moisture into the atmosphere.

38
00:02:08,367 --> 00:02:12,119
This increases the amount and thickness
of clouds present,

39
00:02:12,119 --> 00:02:15,626
which can cool the atmosphere
by blocking more sunlight.

40
00:02:15,626 --> 00:02:18,077
But this negative feedback loop
is short-lived,

41
00:02:18,077 --> 00:02:20,441
due to the brief Arctic summers.

42
00:02:20,441 --> 00:02:22,824
For the rest of the year, 
when sunlight is scarce,

43
00:02:22,824 --> 00:02:24,649
the increased moisture and clouds

44
00:02:24,649 --> 00:02:28,325
actually warm the surface
by trapping the Earth's heat,

45
00:02:28,325 --> 00:02:32,491
turning the feedback loop positive
for all but a couple of months.

46
00:02:32,491 --> 00:02:35,509
While negative feedback loops
encourage stability

47
00:02:35,509 --> 00:02:38,049
by pushing a system towards equilibrium,

48
00:02:38,049 --> 00:02:43,990
positive feedback loops destabilize it
by enabling larger and larger deviations.

49
00:02:43,990 --> 00:02:47,083
And the recently increased impact
of positive feedbacks

50
00:02:47,083 --> 00:02:50,387
may have consequences 
far beyond the Arctic.

51
00:02:50,387 --> 00:02:51,706
On a warming planet,

52
00:02:51,706 --> 00:02:57,072
these feedbacks ensure that the North Pole
warms at a faster rate than the equator.

53
00:02:57,072 --> 00:03:00,058
The reduced temperature differences
between the two regions

54
00:03:00,058 --> 00:03:02,662
may lead to slower jet stream winds

55
00:03:02,662 --> 00:03:06,936
and less linear atmospheric circulation
in the middle latitudes,

56
00:03:06,936 --> 00:03:09,374
where most of the world's 
population lives.

57
00:03:09,374 --> 00:03:12,301
Many scientists are concerned
that shifts in weather patterns

58
00:03:12,301 --> 00:03:14,959
will last longer and be more extreme,

59
00:03:14,959 --> 00:03:18,912
with short term fluctuations becoming
persistent cold snaps,

60
00:03:18,912 --> 00:03:22,539
heat waves, droughts and floods.

61
00:03:22,539 --> 00:03:25,883
So the Arctic sensitivity doesn't just
serve as an early warning alarm

62
00:03:25,883 --> 00:03:28,418
for climate change 
for the rest of the planet.

63
00:03:28,418 --> 00:03:32,593
Its feedback loops can affect us
in much more direct and immediate ways.

64
00:03:32,593 --> 00:03:34,654
As climate scientists often warn,

65
00:03:34,654 --> 00:03:38,447
what happens in the Arctic
doesn't always stay in the Arctic.