global warming and carbon emissions.

是全球变暖和碳排量问题
Again, leaving aside the science,

抛开科学层面来说
about which I'm sure some of you know more than me here,

我相信在座的一些同学比我知道的还多
the issue of carbon emissions is a Prisoners' Dilemma.

碳排放问题也是个囚徒困境
Each of us individually has an incentive to emit carbons as usual.

通常我们每个人都有排碳的动机
If everyone else is cutting down I don't have too,

如果大家都想减排我没必要跟风
and if everyone else does cut down I don't have to,

如果别人真的减排了又与我何干
I end up using hot water and driving a big car and so on.

我照样用着热水开着大排量汽车
In each of these cases we end up with a bad outcome,

这些情况都导致了糟糕的结果
so this is socially important.

所以这点在社会层面上很重要
This is not just some abstract thing going on in a class in Yale.

这不仅仅是耶鲁课堂上的抽象概念
We need to think about solutions to this,

从一上课开始我们就应该开始