Delegates left the Bali climate change talks in December 2007 with high hopes that a grand bargain on reducing greenhouse gas emissions would be secured by now.
The biggest decision – a binding international agreement on reducing greenhouse gas emissions – is likely to be pushed off until next December, when another round of climate talks are scheduled for Mexico City. Nevertheless, two weeks in Copenhagen will yield insights into global efforts to control industrial emissions and the warming of the planet.
Below are some key questions:
What might success in Copenhagen look like?
Low expectations at the start of the conference may not be a bad thing.
"I think there was a sense all along that we were not going to be able to reach an international binding legal agreement in Copenhagen," says Eileen Claussen, who heads the Pew Center on Global Climate Change in Arlington, Va. But only in the last week did leaders acknowledge this. The results may disappoint some, she said, but added that it's a more realistic track.
Three areas will be the keys to "success" in Copenhagen.
Emissions reductions. What target will wealthy countries and major developing countries like China, India and Brazil set for reducing emissions between now and 2050? An interim target for 2020 will also be set.
Immediate action. What actions will countries take immediately after the meeting to reduce emissions, move new green technologies into the marketplace, and help developing countries adopt cleaner power sources?
Money. How much cash will rich country's pony to help poorer ones pay for green technologies they will need to spur economic growth in a climate-friendly way?
If the meeting yields progress on those three objectives "it will be a resounding success," says Yvo de Boer, executive secretary of the UN Framework Convention on Climate Change.
Observers say the meeting will have failed if it ends without a clear mandate to wrap up binding legal language on reducing emissions no later than December 2010. Otherwise, the process is likely to unravel into prolonged haggling over a new pact's rules of the road, much as the 1997 Kyoto Protocol did.
Money also looms large. Many in the developing world say their richer counterparts need to pay to help them adjust to a changing climate and to reducing their own emissions. A clear, quick-start financing package for these poorer nations might offset developing country anger over what they view as limited emissions reductions promises by major industrial nations.
Industrial countries want a transparent way to verify that developing countries are following through on promises, but several developing countries say such oversight would be a threat to national sovereignty.
What are countries offering on greenhouse-gas reductions?
On Sunday, South Africa said it would slow the growth of its emissions to 34 percent below the current annual growth rate by 2020 and to 42 percent by 2025, as long as international aid is forthcoming.
India has offered to improve its energy efficiency to 20 or 25 percent better than 2005 levels, provided it gets international money.
China has offered up a 40 to 45 percent efficiency improvement on 2005.
Brazil has put up actual emissions reductions of 36 to 39 percent below 1994 levels by 2020, if it gets financial help.
Mexico has promised actions through 2012 that put it on track to reduce emissions by 50 percent by 2050, but anything after 2012 is contingent on international aid.
What is the combined effect of those emissions offers?
Political leaders have agreed to try to hold warming to 2 degrees Celsius (3.6 degrees Fahrenheit) over preindustrial levels. If that is to be met, scientists say that developed countries will need to cut their greenhouse-gas emissions by 25 to 40 percent by 2020 and by 80-95 percent by 2050. Developed countries must substantially reduce the growth rate in their emissions.
But current promises on emissions reductions fall well short of meeting those targets. Rich-countries have currently offered an 8 to 14 percent reduction below 1990 levels by 2020, according to climateactiontracker.org.
Russia's numbers are interesting: Emissions have been so low following the collapse of the old Soviet Union that the country's emissions could rise from now and still meet the country's 2020 target, some analysts say.
For developing countries, China and India are the heavy hitters. China's target is widely seen as "business as usual," although that interpretation varies. India's numbers also are seen as falling into a business-as-usual category.
In fact, India's number is so "conservative" that India could offer up more-ambitious goals and still fall within business as usual, explains David Pumphrey, an international energy analyst with the Center for Strategic and International Studies in Washington.
What are the likely sticking points?
As many in the developing world – the countries whose populations are likely to suffer from the effects of climate change the most – see it, rich country targets are not ambitious enough.
And much needs to be done on the financial front for both short-term aid and long term aid. The aid would be used for adaptation efforts, the purchase of green technologies, and efforts to help developing countries build in-house technical expertise. In the short term, countries are talking about $10 billion a year over the next three years. Beyond that, the number rises to $100 billion a year through 2020. But if developed countries are going to put up that much money, they want verification that developing countries are actually reducing the growth of emissions.
How much impact might 'Climategate' have?
This remains to be seen. In the US, Republican members of Congress are asking the Environmental Protection Agency (EPA) to forestall any effort to regulate carbon dioxide emissions under the Clean Air Act until a full, transparent investigation has taken place on allegations that fudged data played a role in establishing the link between industrial CO2 emissions and global warming. Internationally, the Saudi Arabian's are using the hacked letters from the University of East Anglia's Climatic Research Unit to argue that there's no need for any new climate treaty. The BBC quoted the country's chief negotiator as saying it will have a huge impact on the talks.
The UN negotiating process requires unanimous consent to reach decisions. So the Saudis alone could hold things up. But the Saudis often threaten to block movement as a negotiating position. The oil rich Kingdom's long-time pitch is this: Any new agreement should contain payments to Saudi Arabia to make up for oil revenues it would lose as the world weans itself from oil.