Two full years ago in Bali delegates agreed that this December in Copenhagen would be the time and place to finalize an international climate deal. And with very few exceptions (looking at you, Mr. Inhofe), everyone heading to Copenhagen wants to get a deal done. So, after all this time and given the widespread motivation, what exactly is the holdup?

Compromise, it seems, is really tough, especially when sovereign nations are being asked to make concessions that are perceived to threaten their economies (as industrialized countries fear), their development plans (see China and India), or even their very survival (in the case of the most vulnerable and least developed countries).

So there remain a tricky set of sticking points, or specific contentious issues, that could make or break these talks. These range from higher-level, bird's eye view shared vision goals and targets to the specific tools and mechanisms that will be essential to meeting those goals. Let's take a closer look.

Shared vision goals

A potential agreement will almost certainly have a "shared vision" statement, in which  the the long-term goals of preserving a habitable planet will effectively be boiled down to a couple of closely-related numbers--the target concentration of CO2 in the atmosphere measured in parts per million (ppm), and the target "limit" for global temperature rise.

For the past couple years, conventional climate wisdom has called for a 450 ppm concentration target, which most scientists think will probably keep the planet from warming more than 2 degrees Celcius. But the most recent science points to a 350 ppm ceiling (roughly a 1.5 degree rise), as NASA climatologist Jim Hansen wrote, "if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted." Over 80 small island and developing nations support the 350ppm/1.5 degree target, as do many international climate, human rights, and justice organizations. Whether the shared vision section will include a target concentration, a target ceiling on temperature rise, or neither or both will be the source of some argument. Whichever level of ambition decided for those actual numbers will require a massive concession from the rich or poor factions.

Mitigation Targets

Perhaps the most fundament of all questions: How much will developed nations agree to reduce their emissions by? The UNFCCC has suggested that industrialized nations should commit to 25-40% reductions from 1990 levels by 2020 (and longer term goals of 80-85% by 2050). This is ambitious--right now, Japan has committed to just an 8% cut by 2020, Russia, 10-15%, and many countries none at all. The U.S. has offered a provisional target (if domestic legislation passes) that amounts to a mere 4% reduction. It's hard to see any developing countries agreeing to such modest effort from the world's largest per capita greenhouse gas emitter.

Then there's the question of the emerging developing economies, like China and India and Brazil. They won't be asked or expected to cut emissions, but a commitment limit future growth of emissions and cut down from "business as usual" emissions projections would go a long way in securing deeper cuts from the industrialized world.

Finance

Financing a global climate deal is absolutely the fundamental debate that runs through just about every other issue, particularly mitigation and adaptation in developing countries. Developed nations will be pressured to live up to their historical responsibility--having grown rich by burning fossil fuels--and help fund mitigation and adaptation initiatives. The big question is where will the money come from: direct contributions of public money (which wealthy power players like the U.S., the E.U., Russia, and Japan hate) or market mechanisms like cap-and-trade credits and offsets (which they like). It's no small purse we're talking about--developing countries are calling for hundreds of billions every year.

Exactly how much will have to be determined, but equally important, and hotly debated, is how the money will be handled. Wealthy nations want the security of an existing organization, specifically the World Bank, to hold the purse strings and also want recipients to verify and report on how that money is being spent. Poor countries feel that they've been screwed by the World Bank for decades now, and want a new independent body to act as bursar. And they certainly don't want to have to spend a significant portion of the cash on creating systems for measurement, reporting and verification.   

Technology Transfer

Technological advances and the spread of existing clean energy technologies are the core of a global climate solution. With the (significant) exceptions of China and India, most clean tech innovation comes from the developed world. Negotiators will wrestle with the question of how to best transfer these technologies to developing countries. Financing, of course, will be a big issue. But more nuanced is discussion of intellectual property rights (IPRs). Proposals from developing countries suggest a relaxation of IPRs and better incentives for patent holders to grant free transfers internationally. Patent-holding countries have thus far balked at such proposals. India has been the most vocal calling out rich countries--the U.S. in particular--for holding out.

REDD

Nearly 20% of the world's greenhouse gas emissions is a result of deforestation and forest decay, making it a massive mitigation opportunity in many tropical, developing countries with vast forests. Mechanisms for REDD (Reducing Emissions from Deforestation and Degradation) essentially involve rich countries paying poor ones to prevent the loss of forests. The problem is, nobody knows how exactly these mechanisms would work. How they'd be designed to ensure the environmental integrity (to address "leakage"--shifts in deforestation to unprotected areas, and "non-permanence"--resumed cutting after protection funds are issued) and economic fairness will be long-debated, likely even after COP15 adjourns.

Adaptation

Even if Copenhagen resulted in the immediate stabilization of greenhouse gas emissions-and it won't-the planet would still be locked into significant warming. The need for adaptation measures is now broadly accepted, and most countries are already working on plans or programs to combat the actual impacts of climate change. But distinguishing "adaptation" programs from "development" initiatives gets cloudy, and fireworks already set off last week when some European Union memos were leaked, publicizing their intention to shift existing development funds to adaptation purposes. The developing world demands new money.

Enforcement

The current Kyoto agreement has no formal enforcement. Most would argue that this hasn't worked. This treaty will need some teeth with clearly defined and binding penalties for countries that slouch out of their commitments. Negotiators will somehow have to agree on who will monitor and enforce the treaty. Emissions audits, progress reports, and penalties can't reliably be left in the hands of the countries themselves. The legal mechanisms for compliance and enforcement almost certainly won't be hashed out in Copenhagen, but the contours for the structure should be clear by the end of the two weeks, and a hard deadline will likely be debated. Developing countries want this agreement to be as immediately actionable and enforceable as possible. Developed countries don't have the same sense of urgency.