New Scientist has this excellent page with a high level explanation of what the upcoming Copenhagen climate change summit is about and why it is so important to all of us.

Goal
The Kyoto Protocol was the previous agreement on reducing greenhouse gas emissions. Kyoto now needs to be replaced and that is why the world is meeting in Copenhagen.

The world’s nations must agree on how they are going to massively reduce carbon emissions. This is required in order to avoid a dangerous increase in global temperatures.

It is already too late to avoid damage – the goal in Copenhagen is to agree on how to limit the damage we do to ourselves.

Rich vs poor
The rich world has already emitted way more than its share. If we are going to avoid dangerous global warming then the rich world is going to have to foot more of the bill.

Not only does the rich world have to reduce emissions by more, but it should also be offsetting past emissions.

Deal breakers
Reducing climate change is going to be difficult and very expensive. It requires global cooperation, so plenty could go wrong in Copenhagen.

• The US must agree on serious cuts (they were the only ones to ignore Kyoto). Getting the US Congress to agree to anything tough is very tricky. If the US is not serious then China and India will start to pull out too. Then the whole deal is pointless.
• Developing or recently developed nations feel that they shouldn’t be penalized for the past excesses of rich nations. This is reasonable but could be a big sticking point.
• Oil rich nations may try to ‘torpedo’ the deal to protect their own interests and because they emit huge amounts of carbon.