联合国政府间气候变化专门委员会(IPCC)预测，
[00:03.56]the Intergovernmental Panel on Climate Change predicts that，
如果全世界保持现在的经济模式不变，
[00:06.53]there is a fifty-fifty chance the temperature will exceed 5 degrees by the end of this century.
本世纪末气温5度的可能性是50%。
[00:13.42]This increase may not sound like much, but let me remind you that during the last ice age,
这听起来好像不多，但是让我来提醒你，上一次的冰河期，
[00:19.08]the world was only 6 degrees colder.
地球的气温也仅仅下降了6度。
[00:22.10]During this time, most of Canada and the United States down to Ohio and Pennsylvania were covered year round by a glacier.
那时，俄亥俄州和宾夕法尼亚州以下的大部分美国和加拿大的土地，都终年被冰川覆盖。
[00:29.49]A world 5 degrees warmer will be very different. The change will be so rapid that many species,
气温上升5度的地球，将是一个非常不同的地球。由于气候变化来得太快，
[00:36.18]including Humans, will have a hard time adapting.
包括人类在内的许多生物，都将很难适应。
[00:40.14]I’ve been told for example, that, in a much warmer world, insects were bigger.
比如，有人告诉我，在更温暖的环境中，昆虫的个头将变大。
[00:44.04]I wonder if this thing buzzing around is a precursor.
我不知道现在身旁嗡嗡叫的这只大苍蝇，是不是就是前兆。
[00:50.05]We also face the specter of nonlinear “tipping points” that may cause much more severe changes.
我们还面临另一个威胁，那就是非线性的“气候引爆点”，这会带来许多更严重的变化。
[00:56.03]An example of a tipping point is the thawing of the permafrost.
“气候引爆点”的一个例子就是永久冻土层的融化。
[01:00.14]The permafrost contains immense amounts of frozen organic matter that have been accumulating for millennia.
永久冻土层经过千万年的累积形成，其中包含了巨量的冻僵的有机物。
[01:06.47]If the soil melts, microbes will spring to life and cause this debris to rot.
如果冻土融化，微生物就将广泛繁殖，使得冻土层中的有机物快速腐烂。
[01:12.07]The difference in biological activity below freezing and above freezing is something we are all familiar with.
冷冻后的生物和冷冻前的生物在生物学特性上的差异，我们都很熟悉。
[01:18.20]Frozen food remains edible for a very long time in the freezer, but once thawed, it spoils quickly.
在冷库中，冷冻食品在经过长时间保存后，依然可以食用。但是，一旦解冻，食品很快就腐烂了。
[01:25.05]How much methane and carbon dioxide might be released from the rotting permafrost?
一个腐烂的永久冻土层，将释放出多少甲烷和二氧化碳?
[01:29.46]If even a fraction of the carbon is released,
即使只有一部分的二氧化碳被释放出来，
[01:32.33]it could be greater than all the greenhouse gases we have released since the beginning of the industrial revolution.
可能也比我们从工业革命开始释放出来的所有温室气体还要多。
[01:39.29]Once started, a runaway effect could occur.
这种事情一旦发生，局势就失控了。
