我怀着回报社会的想法，开始了教学生涯。
[00:02.52]But I received more than I gave. This brings me to the final movement of this speech.
然而，我得到的多于我付出的。这就引出了这次演讲的最后一篇乐章。
[00:08.31]It begins with a story about an extraordinary scientific discovery and a new dilemma that it poses.
首先我要讲一个了不起的科学发现，以及由此带来的新挑战。
[00:15.15]It’s a call to arms and about making a difference.
它是一个战斗的号令，到了做出改变的时候了。
[00:19.39]So here is the movement.In the last several decades, our climate has been changing.
现在开始本次演讲的第一章。过去几十年中，我们的气候一直在发生变化。
[00:25.47]Climate change is not new: the Earth went through six ice ages in the past 600,000 years.
气候变化并不是现在才有的，过去60万年中地球就发生了6次冰河期。
[00:32.47]However, recent measurements show that the climate has begun to change rapidly.
但是，最新的测量表明气候变化加速了。
[00:37.27]The size of the North Polar Ice Cap in the month of September is only half the size it was a mere 50 years ago.
9月份，北极冰盖的覆盖面积只相当于50年前的一半。
[00:46.04]The sea level which been rising since direct measurements began in 1870 is now five times faster,
1870年起，人们开始测量海平面上升的速度，
[00:53.41]at a rate now five times faster, than at the beginning of recorded measurements.
现在海平面上升的速度是那时的5倍。
[00:59.19]Here’s the remarkable scientific discovery. For the first time in human history,
一个重大的科学发现就这样产生了。
[01:05.45]science is now making predictions of how our actions will affect the world 50 and 100 years from now.
科学第一次预测出我们的行为对50到100年后的世界有何影响。
[01:12.32]These changes are due to an increase in carbon dioxide put into the atmosphere since the beginning of the Industrial Revolution.
这些变化的原因是，从工业革命开始，人类排放到大气中的二氧化碳增加了。
[01:21.48]The Earth has warmed up by roughly 0.8 degrees Celsius since the beginning of the Revolution.
这使得地球的平均气温上升了0.8摄氏度。
[01:28.38]There is already approximately a 1 degree rise built into the system, even if we stop all greenhouse gas emissions today.
即使我们立刻停止所有温室气体的排放，气温仍然将比过去上升大约1度。
[01:35.55]Why? It will be decades to warm up the deep oceans before the temperature reaches a new equilibrium.
为什么呢?因为在气温达到均衡前，海水温度的上升将持续几十年。
