Why is the world warming up?

A brief answer to one of the key questions about climate change: Why is the world warming up? (Written by Myles Allen, David Biello and George Zaidan)

Why is the world warming up?

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

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

Our atmosphere, the glass roof and walls,

reflects some of that energy,

but most of it passes right through
and heats everything up.

Much of that heat
used to escape back into space,

keeping us at a stable, warm temperature.

But then something changed.

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

What does all that greenhouse gas do?

It makes the glass
of our greenhouse thicker.

Thicker glass means heat escapes
into space much more slowly.

And don't forget, energy from the sun

is still streaming in
just as quickly as before.

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

and, eventually...

living.

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