Why is the world warming up?

为什么世界在变暖？

Let's think of Earth for just a moment as a greenhouse.

让我们暂时把地球想象成一个温室。

Every second, a huge amount of energy smashes into our greenhouse.

每秒钟，都有大量的能量不断涌入我们的温室。

Our atmosphere, the glass roof and walls, reflects some of that energy,  but most of it passes right through and heats everything up.

我们的大气层， 即玻璃屋顶和墙壁，反射了部分能量，但大部分能量直接穿过了这层屏障， 让温室内的一切都开始升温。

Much of that heat used to escape back into space, keeping us at a stable, warm temperature.

其中大部分热量被释放回太空，让温室内部得以保持稳定舒适的温度。

But then something changed.

但是后来事情变了。

Humans began to spew enough carbon dioxide to fill billions of greenhouses each day.

人类开始每天排放足够填满数十亿个温室的二氧化碳。

What does all that greenhouse gas do?

那些温室气体有什么作用？

It makes the glass of our greenhouse thicker.

它会使我们温室的玻璃更厚。

Thicker glass means heat escapes into space much more slowly.

较厚的玻璃意味着热量向空间扩散的速度要慢得多。

And don't forget, energy from the sun is still streaming in just as quickly as before.

别忘了，来自太阳的能量仍然照常快速地流入。

The result is a planet with temperatures too hot for our liking and,

最后的结果就是， 地球的温度变得不再宜居，

eventually... living.

最终—— 生命也将无法存活。