[Script Info]
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[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.76,0:00:09.13,Default,,0000,0000,0000,,The area surrounding the North Pole
Dialogue: 0,0:00:09.13,0:00:14.05,Default,,0000,0000,0000,,may seem like a frozen and desolate\Nenvironment where nothing ever changes.
Dialogue: 0,0:00:14.05,0:00:19.01,Default,,0000,0000,0000,,But it is actually a complex \Nand finely balanced natural system,
Dialogue: 0,0:00:19.01,0:00:23.31,Default,,0000,0000,0000,,and its extreme location \Nmakes it vulnerable to feedback processes
Dialogue: 0,0:00:23.31,0:00:27.07,Default,,0000,0000,0000,,that can magnify even tiny changes\Nin the atmosphere.
Dialogue: 0,0:00:27.07,0:00:32.28,Default,,0000,0000,0000,,In fact, scientists often describe \Nthe Arctic as the canary in the coal mine
Dialogue: 0,0:00:32.28,0:00:36.26,Default,,0000,0000,0000,,when it comes to predicting the impact\Nof climate change.
Dialogue: 0,0:00:36.26,0:00:39.70,Default,,0000,0000,0000,,One major type of climate feedback\Ninvolves reflectivity.
Dialogue: 0,0:00:39.70,0:00:41.95,Default,,0000,0000,0000,,White surfaces, like snow and ice,
Dialogue: 0,0:00:41.95,0:00:46.03,Default,,0000,0000,0000,,are very effective at reflecting\Nthe sun's energy back into space,
Dialogue: 0,0:00:46.03,0:00:51.11,Default,,0000,0000,0000,,while darker land and water surfaces\Nabsorb much more incoming sunlight.
Dialogue: 0,0:00:51.11,0:00:55.09,Default,,0000,0000,0000,,When the Arctic warms just a little,\Nsome of the snow and ice melts,
Dialogue: 0,0:00:55.09,0:00:58.11,Default,,0000,0000,0000,,exposing the ground and ocean underneath.
Dialogue: 0,0:00:58.11,0:01:01.97,Default,,0000,0000,0000,,The increased heat absorbed by\Nthese surfaces causes even more melting,
Dialogue: 0,0:01:01.97,0:01:03.60,Default,,0000,0000,0000,,and so on.
Dialogue: 0,0:01:03.60,0:01:07.11,Default,,0000,0000,0000,,And although the current situation\Nin the Arctic follows the warming pattern,
Dialogue: 0,0:01:07.11,0:01:09.36,Default,,0000,0000,0000,,the opposite is also possible.
Dialogue: 0,0:01:09.36,0:01:12.61,Default,,0000,0000,0000,,A small drop in temperatures\Nwould cause more freezing,
Dialogue: 0,0:01:12.61,0:01:15.94,Default,,0000,0000,0000,,increasing the amount \Nof reflective snow and ice.
Dialogue: 0,0:01:15.94,0:01:18.48,Default,,0000,0000,0000,,This would result in less sunlight \Nbeing absorbed,
Dialogue: 0,0:01:18.48,0:01:22.76,Default,,0000,0000,0000,,and lead to a cycle of cooling,\Nas in previous ice ages.
Dialogue: 0,0:01:22.76,0:01:26.63,Default,,0000,0000,0000,,Arctic sea ice is also responsible\Nfor another feedback mechanism
Dialogue: 0,0:01:26.63,0:01:28.27,Default,,0000,0000,0000,,through insulation.
Dialogue: 0,0:01:28.27,0:01:30.21,Default,,0000,0000,0000,,By forming a layer on the ocean's surface,
Dialogue: 0,0:01:30.21,0:01:33.45,Default,,0000,0000,0000,,the ice acts as a buffer between\Nthe frigid arctic air
Dialogue: 0,0:01:33.45,0:01:36.43,Default,,0000,0000,0000,,and the relatively \Nwarmer water underneath.
Dialogue: 0,0:01:36.43,0:01:39.45,Default,,0000,0000,0000,,But when it thins, breaks, \Nor melts in any spot,
Dialogue: 0,0:01:39.45,0:01:41.64,Default,,0000,0000,0000,,heat escapes from the ocean,
Dialogue: 0,0:01:41.64,0:01:45.72,Default,,0000,0000,0000,,warming the atmosphere \Nand causing more ice to melt in turn.
Dialogue: 0,0:01:45.72,0:01:48.96,Default,,0000,0000,0000,,Both of these are examples\Nof positive feedback loops,
Dialogue: 0,0:01:48.96,0:01:50.79,Default,,0000,0000,0000,,not because they do something good,
Dialogue: 0,0:01:50.79,0:01:54.90,Default,,0000,0000,0000,,but because the initial change \Nis amplified in the same direction.
Dialogue: 0,0:01:54.90,0:01:57.25,Default,,0000,0000,0000,,A negative feedback loop,\Non the other hand,
Dialogue: 0,0:01:57.25,0:01:59.70,Default,,0000,0000,0000,,is when the initial change\Nleads to effects
Dialogue: 0,0:01:59.70,0:02:02.29,Default,,0000,0000,0000,,that work in the opposite direction.
Dialogue: 0,0:02:02.29,0:02:05.28,Default,,0000,0000,0000,,Melting ice also causes \Na type of negative feedback
Dialogue: 0,0:02:05.28,0:02:08.37,Default,,0000,0000,0000,,by releasing moisture into the atmosphere.
Dialogue: 0,0:02:08.37,0:02:12.12,Default,,0000,0000,0000,,This increases the amount and thickness\Nof clouds present,
Dialogue: 0,0:02:12.12,0:02:15.63,Default,,0000,0000,0000,,which can cool the atmosphere\Nby blocking more sunlight.
Dialogue: 0,0:02:15.63,0:02:18.08,Default,,0000,0000,0000,,But this negative feedback loop\Nis short-lived,
Dialogue: 0,0:02:18.08,0:02:20.44,Default,,0000,0000,0000,,due to the brief Arctic summers.
Dialogue: 0,0:02:20.44,0:02:22.82,Default,,0000,0000,0000,,For the rest of the year, \Nwhen sunlight is scarce,
Dialogue: 0,0:02:22.82,0:02:24.65,Default,,0000,0000,0000,,the increased moisture and clouds
Dialogue: 0,0:02:24.65,0:02:28.32,Default,,0000,0000,0000,,actually warm the surface\Nby trapping the Earth's heat,
Dialogue: 0,0:02:28.32,0:02:32.49,Default,,0000,0000,0000,,turning the feedback loop positive\Nfor all but a couple of months.
Dialogue: 0,0:02:32.49,0:02:35.51,Default,,0000,0000,0000,,While negative feedback loops\Nencourage stability
Dialogue: 0,0:02:35.51,0:02:38.05,Default,,0000,0000,0000,,by pushing a system towards equilibrium,
Dialogue: 0,0:02:38.05,0:02:43.99,Default,,0000,0000,0000,,positive feedback loops destabilize it\Nby enabling larger and larger deviations.
Dialogue: 0,0:02:43.99,0:02:47.08,Default,,0000,0000,0000,,And the recently increased impact\Nof positive feedbacks
Dialogue: 0,0:02:47.08,0:02:50.39,Default,,0000,0000,0000,,may have consequences \Nfar beyond the Arctic.
Dialogue: 0,0:02:50.39,0:02:51.71,Default,,0000,0000,0000,,On a warming planet,
Dialogue: 0,0:02:51.71,0:02:57.07,Default,,0000,0000,0000,,these feedbacks ensure that the North Pole\Nwarms at a faster rate than the equator.
Dialogue: 0,0:02:57.07,0:03:00.06,Default,,0000,0000,0000,,The reduced temperature differences\Nbetween the two regions
Dialogue: 0,0:03:00.06,0:03:02.66,Default,,0000,0000,0000,,may lead to slower jet stream winds
Dialogue: 0,0:03:02.66,0:03:06.94,Default,,0000,0000,0000,,and less linear atmospheric circulation\Nin the middle latitudes,
Dialogue: 0,0:03:06.94,0:03:09.37,Default,,0000,0000,0000,,where most of the world's \Npopulation lives.
Dialogue: 0,0:03:09.37,0:03:12.30,Default,,0000,0000,0000,,Many scientists are concerned\Nthat shifts in weather patterns
Dialogue: 0,0:03:12.30,0:03:14.96,Default,,0000,0000,0000,,will last longer and be more extreme,
Dialogue: 0,0:03:14.96,0:03:18.91,Default,,0000,0000,0000,,with short term fluctuations becoming\Npersistent cold snaps,
Dialogue: 0,0:03:18.91,0:03:22.54,Default,,0000,0000,0000,,heat waves, droughts and floods.
Dialogue: 0,0:03:22.54,0:03:25.88,Default,,0000,0000,0000,,So the Arctic sensitivity doesn't just\Nserve as an early warning alarm
Dialogue: 0,0:03:25.88,0:03:28.42,Default,,0000,0000,0000,,for climate change \Nfor the rest of the planet.
Dialogue: 0,0:03:28.42,0:03:32.59,Default,,0000,0000,0000,,Its feedback loops can affect us\Nin much more direct and immediate ways.
Dialogue: 0,0:03:32.59,0:03:34.65,Default,,0000,0000,0000,,As climate scientists often warn,
Dialogue: 0,0:03:34.65,0:03:38.45,Default,,0000,0000,0000,,what happens in the Arctic\Ndoesn't always stay in the Arctic.