Copenhagen is a numbers game: temperatures, emissions, and allowances. But the most important numbers are probably the ones preceded by dollar signs.  “Money is even more important now the parties are coming up with only a political statement not a legally binding agreement,” says David McCauley, Principal Climate Change Specialist, Asian Development Bank.

Political statements won’t reduce emissions; cash will. So said South Africa the day before talks began. It offered to cut carbon emissions to 34 percent below expected levels by 2020, but only if the rich world provided money to help.

Then the president of the African Development Bank, Donald Kaberuka, said he wanted 40 billion dollars a year from rich countries “to enable low-income countries to adapt.” These statements crystallize the money matters at the heart of Copenhagen.

Will the rich pay the poor to go green? Will the rich compensate the poor for wrecking their environment? Climate aid  The Framework Convention on Climate Change agreed in Rio 17 years ago is clear: “The developed country Parties…shall provide new and additional financial resources to meet the agreed full costs incurred by developing country Parties.”

The key phrase is “new and additional”. Climate aid should not be development aid shifted from feeding the hungry to building wind farms. This “additionality” has a flip side. Developing countries must not claim climate aid for clean energy projects they would have built anyway.  Ultimately, “what means the most for making Copenhagen a success is that developed countries come forward with specific money,” said Connie Hedegaard, the Danish environment minister.

Without that money, the most vulnerable countries—island nations, Bangladesh, sub-Saharan Africa—can’t protect their populations. Kaberuka says climate change costs Africa almost 3 percent of GDP every year.  And without that money, big-emitting developing countries like China and India may not commit to carbon cuts that threaten to keep their people poor. Without them there can be no real climate deal.

The 100 billion dollar question  Early in 2009, the G77/China bloc of developing nations laid down the gauntlet. It proposed that the industrialized world devote 0.5 to 1.0 percent of annual GDP—200 to 400 billion dollars—to helping poor countries develop low-carbon economies and adapt to unavoidable climate change. The World Bank and United Nations agree 100 billion dollars a year is a fair amount.

These colossal sums frighten rich countries. But just how big are the numbers? “To put this into perspective, the Iraq war costs the United States 200 billion dollars annually,” says Benito Muller, Director, Energy and Environment, Oxford Institute of Energy Studies.