TED演讲:对最近气候趋势的警告(1)

 　　Last year I showed these two slides so that demonstrate that the arctic ice cap, 去年我给各位展示了两个关于北极冰帽的演示，

　　which for most of the last three million years has been the size of the lower 48 states, has shrunk by 40 percent. 在过去三百万年中，其面积由相当于美国南方48州面积总和缩减了40%。

　　But this understates the seriousness of this particular problem because it doesn't show the thickness of the ice. 但这些没能完全说明这个问题的严重性，因为这没有表示出冰帽的厚度。

　　The arctic ice cap is, in a sense, the beating heart of the global climate system. 感觉上，北极冰帽就好象全球气候系统中跳动的心脏。

　　It expands in winter and contracts in summer. 冬天心脏舒张，夏天心脏收缩。

　　The next slide I show you will be a rapid fast-forward of what's happened over the last 25 years. 下面我要展示的是在过去25年里的极剧变化。

　　The permanent ice is marked in red. 红色的是永冻冰。

　　As you see, it expands to the dark blue -- that's the annual ice in winter, and it contracts in summer. 你看，它正在变成深蓝色，这是每年冬天形成的年度冰，在夏天永冻冰收缩。

　　The so-called permanent ice, five years old or older, you can see is almost like blood, spilling out of the body here. 所谓的“永冻”，是指形成五年或更久的冰，你看，这也像血液一样输送到身体各部位。

　　In 25 years it's gone from this, to this. 在25年的时间里，它从这里到了这里。

　　This is a problem because the warming heats up the frozen ground around the Arctic Ocean, 值得注意的是，温室效应使得北冰洋周围的冻土层受热，

　　where there is a massive amount of frozen carbon which, when it thaws¹, is turned into methane² by microbes. 而这里有大量被冻封的碳（干冰），解冻时，微生物降解碳形成甲烷。

　　Compared to the total amount of global warming pollution in the atmosphere, 如果突破顶点，温室气体排放量

　　that amount could double if we cross this tipping point. 将是现有大气层中的全球温室污染总量。

　　Already in some shallow lakes in Alaska, methane is actively³ bubbling up out of the water. 在阿拉斯加的一些浅湖里已经可以看到水中探头的沼气泡。

　　Professor Katey Walter from the University of Alaska went out with another team to another shallow lake last winter. 去年冬天，阿拉斯加大学的Katey Walter教授结队去了一个浅湖。

1 thaws   

n.（足以解冻的）暖和天气( thaw的名词复数 )；（敌对国家之间）关系缓和v.（气候）解冻( thaw的第三人称单数 )；（态度、感情等）缓和；（冰、雪及冷冻食物）溶化；软化

参考例句：

• The sun at noon thaws the ice on the road. 中午的阳光很快把路上的冰融化了。 来自辞典例句
• It thaws in March here. 在此地化雪的季节是三月。 来自辞典例句

2 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

3 actively   

adv.积极地，勤奋地

参考例句：

• During this period all the students were actively participating.在这节课中所有的学生都积极参加。
• We are actively intervening to settle a quarrel.我们正在积极调解争执。