It will cost somewhere between $100 billion and $1 trillion each year around the globe to help developing countries convert to less-polluting technology and help mitigate the direct impacts of climate change, economists say.

That's why it's no surprise that funding is a major obstacle on the road to a new climate pact, which will hopefully be negotiated in Copenhagen in December.

According to the New York Times, many developing countries have made it clear that they will not sign a treaty unless they get money to help them make the transition. Developing nations have already signed on in principle, and positive language has already been written into the agreed-upon structure of the treaty.

But to date there is no concrete strategy to raise such huge sums. There is not even agreement about which nations should pay or in what proportion.

According to the Guardian newspaper, the Obama administration is hoping to win new commitments to fight global warming from China and India in back-to-back summits next month, including the first Indian emissions trading scheme.