COPENHAGEN — In the end, the COP15 climate conference here was about numbers.
"We need numbers on the table. Specifically, we need developed nations to commit to short-term greenhouse-gas reductions between 2012 and 2020," Yvo de Boer, executive secretary of the United Nations Convention on Climate Change, said just before the 15th Conference of the Parties started Dec. 7.
"We also need short-term financing of climate mitigation in developing countries, and a commitment to long-term financing," he added.
The first set of numbers that formed the basis of the Copenhagen negotiations came from science — a Feb. 2007 report by the Intergovernmental Panel on Climate Change warning global warming was unequivocal.
The IPCC report made it clear the safest way to prevent a climate catastrophe would be to take action quickly.
In addition, the IPCC said all nations would have to ensure that global emissions will peak by 2015 in order to keep the Earth's average temperature below 2 degrees C by century's end, although even with 2 degrees as the goal, parts of Africa could see more than a 3-degree rise and massive damage.
The report added that taking action to limit the average rise to 1.5 degrees was best to ensure rising sea levels won't force the evacuations of island states.
These numbers became the basis for negotiations later in 2007 at the U.N. conference in Bali, where parties agreed that emissions reductions for the post-Kyoto Protocol period of 2012 to 2020 would be signed at Copenhagen in 2009.
But many developed nations worried about the huge cost and supply instability problems of switching from fossil fuels to alternative energy sources, a step essential to reducing carbon dioxide concentrations.
At least $30 billion was needed in the short term, various U.N. commissioned studies concluded, while long-term adaption costs were more unpredictable. Figures suggested by the World Bank and private research firms ranged from $100 billion to $200 billion annually for the developing world by 2020.
Thus, negotiators went to Copenhagen with two different sets of numbers, scientific and financial. But well before COP15, the numbers were already causing controversy.
The United States, along with China, the world's largest emitter, angered developed and developing nations by first refusing to announce an emissions-reduction target and then, under President Barack Obama, discarding the recommendation of the IPCC report by suggesting it might be willing to reduce, but by only 17 percent compared with 2005 levels.
U.S. officials spent much time in Copenhagen attempting to convince the skeptical European Union nations, which had agreed to a 20 percent reduction from 1990 levels.
Island states, meanwhile, angry that U.N. negotiators came to Copenhagen talking about limiting the rise to 2 degrees rather than 1.5 as the IPCC report had recommended for their survival, protested during the first week, stopping the conference in the middle of proceedings.
Demonstrators chanted "1.5 to stay alive" as envoys attempted to deal with the issue.
The most taboo scientific number of the conference, however, was the 2015 peak year for emissions.
After de Boer briefly mentioning the importance of agreeing on this in the first couple of days, nobody wanted to deal with the daunting political task of forcing nations to meet a deadline only six years away.
"Science does not wait, and by next year's COP16 in Mexico, the further effects of climate change will be more visible and will hopefully push negotiators to come to agreements on those issues – didn’t agree to here,” de Boer said.
Or, as he indicated, maybe by then, the reality of what the numbers on global warming mean will convince negotiators they cannot afford another conference of the size and scale of Copenhagen that produces only more arguments on numbers rather than an agreement to do something about them.