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The area surrounding the North Pole may seem like a frozen and desolate environment where nothing ever changes.
北极圈附近的冰封世界似乎是一成不变的荒凉之地。
But it is actually a complex and finely balanced natural system,
但其实那里的自然系统，复杂、精妙而又平衡，
and its extreme location makes it vulnerable to feedback processes that can magnify even tiny changes in the atmosphere.
它特殊的位置使得它对气候非常敏感，微小的气候变化都可能被放大。
In fact, scientists often describe the Arctic as the canary in the coal mine
事实上，科学家常把北冰洋形容为“矿井中的金丝雀”，
when it comes to predicting the impact of climate change.
因为北冰洋对气候变化也非常敏感。
One major type of climate feedback involves reflectivity.
气候反馈的一项重要指标是反射性。
White surfaces, like snow and ice, are very effective at reflecting the sun's energy back into space,
像冰雪这样的浅色地表，会有效地把大部分阳光反射回宇宙空间之中，
while darker land and water surfaces absorb much more incoming sunlight.
而土地、海洋这样的深色区域则更擅于吸收阳光。
When the Arctic warms just a little, some of the snow and ice melts, exposing the ground and ocean underneath.
当北冰洋稍稍变暖，少量冰雪消融，暴露出下面的泥土或者海洋。
The increased heat absorbed by these surfaces causes even more melting, and so on.
吸收更多阳光热量导致更多冰雪消融，循环往复。
And although the current situation in the Arctic follows the warming pattern, the opposite is also possible.
现在的北冰洋正处于这样的变暖模式，但变冷的模式亦有可能。
A small drop in temperatures would cause more freezing, increasing the amount of reflective snow and ice.
温度稍稍降低，会使海水更多结冰，冰雪增加了就会反射更多阳光。
This would result in less sunlight being absorbed, and lead to a cycle of cooling, as in previous ice ages.
吸收的阳光则会变少，从而持续的变冷，冰河时代就是如此。
Arctic sea ice is also responsible for another feedback mechanism through insulation.
北冰海冰对另一种对气候的反馈与冰雪的隔离作用有关。
By forming a layer on the ocean's surface,
通过在北冰洋表面形成一层冰层，
the ice acts as a buffer between the frigid arctic air and the relatively warmer water underneath.
冰在寒冷的空气和相对温暖的海水中间形成了一个缓冲区。
But when it thins, breaks, or melts in any spot, heat escapes from the ocean,
如果冰层变薄、破裂、融化，海水中的热量散发到空气中，
warming the atmosphere and causing more ice to melt in turn.
使空气变热，从而更多冰层融化。
Both of these are examples of positive feedback loops, not because they do something good,
这两个都是正反馈循环，“正反馈”并非意味着这是好事，
but because the initial change is amplified in the same direction.
而是指变化会往相同的方向不断强化自身。
A negative feedback loop, on the other hand, is when the initial change leads to effects that work in the opposite direction.
而负反馈则相反，是指初始的改变会导致后续的改变向相反方向进行。
Melting ice also causes a type of negative feedback by releasing moisture into the atmosphere.
冰雪的融化也会导致负反馈，融化后的冰雪会释放更多水汽到大气中。
This increases the amount and thickness of clouds present, which can cool the atmosphere by blocking more sunlight.
这使得云层变厚，云层遮挡住阳光，大气就会变凉。
But this negative feedback loop is short-lived, due to the brief Arctic summers.
但这种负反馈循环非常短暂，因为北冰洋的夏天很短。
For the rest of the year, when sunlight is scarce,
在一年中其他的日子里，缺少阳光，
the increased moisture and clouds actually warm the surface by trapping the Earth's heat,
增加的云量通过吸收地球的热量，反而使地表变暖，
turning the feedback loop positive for all but a couple of months.
这几个月的负反馈又变成了正反馈。
While negative feedback loops encourage stability by pushing a system towards equilibrium,
负反馈导致稳定性会把系统的变化推回原来的平衡点，
positive feedback loops destabilize it by enabling larger and larger deviations.
正反馈则会导致更大的变化，破坏稳定性。
And the recently increased impact of positive feedbacks may have consequences far beyond the Arctic.
最近，正反馈的影响越来越大，可能波及北冰洋之外的世界。
On a warming planet, these feedbacks ensure that the North Pole warms at a faster rate than the equator.
在变暖的星球上，正反馈使极地变热的速度快于赤道。
The reduced temperature differences between the two regions
两个区域之间的温差减小，
may lead to slower jet stream winds and less linear atmospheric circulation in the middle latitudes,
会使喷射气流的速度减弱，中纬度上的线性大气环流亦会减弱，
where most of the world's population lives.
而世界上大部分人口正居住于中纬度地区。
Many scientists are concerned that shifts in weather patterns will last longer and be more extreme,
许多科学家在关注这种气候模式的变化会持续更长时间，造成更极端影响，
with short term fluctuations becoming persistent cold snaps, heat waves, droughts and floods.
短期的气候波动会变成持续的寒流、热浪、干旱、洪水。
So the Arctic sensitivity doesn't just serve as an early warning alarm for climate change for the rest of the planet.
北冰洋对气候的敏感性并非仅是一种警告，提醒我们注意地球上其它地方的气候变化。
Its feedback loops can affect us in much more direct and immediate ways.
它的反馈作用，会以更直接、更迅速的方式影响到我们。
As climate scientists often warn, what happens in the Arctic doesn't always stay in the Arctic.
正如气候学家们所警告的，北冰洋的变化将波及全球。
