Why is the summer of 2010 warmer than previous years?

Answer

If this summer gets warmer than last year (we don’t know yet, it’s still in progress) then that’s a coincidence. Every year is different. But what we can say is that our summers are on average warmer than ten or twenty years ago. They haven’t gotten much warmer, say half a degree in a century, but warmer. By the way, it doesn’t take much to make a difference: in Provence it is on average a few degrees warmer than here, but the plants that grow there and the animals that live there are completely different.

Speaking of thousands of years, the climate fluctuates. There was once an ice age here, and once it was subtropical (in the coal from our mines you can still find imprints of leaves of subtropical plants).

But the warming of the last century has been caused by us: we have put a lot of extra carbon dioxide (CO2) into the air. And that traps heat that would otherwise have leaked into space. The more CO2 there is in the air, the warmer it is on Earth. CO2 is created every time we burn something. Coal, natural gas, oil: when we burn it, we blow CO2 into the air.

The only exception is wood: when we burn it, CO2 is created, but that is just the CO2 that the tree has taken from the air during its life to grow.

We get coal, oil and natural gas – also called the fossil fuels – from under the ground. If we burn it, we put extra CO2 into circulation. It retains extra heat, and it’s getting warmer here again.