We all know that fighting climate change will cost billions. But how much cash do we need?

A new report from scientists says world leaders have massively underestimated these costs. The UN Framework Convention on Climate Change (UNFCCC) estimates that annual global costs of adapting to climate change to be US$40-170 billion. But according to this report, it could be up to three times higher.

The problem, according to the scientists, is that world leaders had not included key sectors such as energy, manufacturing, retailing, mining, tourism and ecosystems. Other sectors that the UNFCCC did include were only partially covered.

This report is crucial in the lead up to Copenhagen. We need some sort of framework setting out the costs for the world to tackle the problem. So far, it looks like we're nowhere near to getting that.