Probably the second most important (only to preventing nuclear war) issue humanity has ever addressed will be discussed at Copenhagen in less than a month. At this conference, delegates from all over the world will work out a global agreement on how to prevent this catastrophe from occurring. In light of this, the next few weeks' Science Fridays will discuss the various aspects of climate change.
The change humans are causing to the climate is known most commonly as global warming or climate change, though the terms global change and climate crisis are also used. The meaning of these is essentially the same. Some people care a lot about which is best; I don't, except that I think global change is vague and likely to be misunderstood. I will use the other terms interchangeably in this series.
I'll start with an overview on how the Earth's climate has worked for most of recorded history, and how we should make sure it returns to.