Copenhagen failed. It was intended to extend Kyoto's caps to the US, China, India, and other the developing countries. Instead the Copenhagen Accord aborted to the Kyoto approach.
That approach was a dead end, and the Accord took a necessary step. It reversed in principle the view that China et al. should do nothing unless paid to, and its failure to mention caps for developing countries will force the world to recognize the obvious.
Failure was predicted by those who study cooperation and international treaties. Climate is a public good, and Kyoto failed to recognize the well-studied difficulties of cooperation in a public-goods game. So the attempted agreement contained multiple fatal flaws. Here is the list:
The US asked India to cap itself at half our per-capita emissions level in 1880 (not a typo). Had China accepted a "trend-line" cap in 2000, it would have been forced to buy roughly $100 B of carbon credits in 2010 from other countries.2. Paid Not to Cooperate
If poor countries became part of the international capping system, as we asked, their profits under the UN's Clean Development Mechanism (CDM) would no longer make sense. CDM effectively pays them to reject caps.
The EU's cap (and the Waxman-Markey cap) are tough to meet. So, both let companies buy CDM offsets instead. Poor countries demand that industrial nations accept much stricter caps so they can sell more profitable CDM credits. The combination of more demands and no cooperation from developing countries caused the deadlock in Copenhagen.3. No Enforcement
There is no meaningful penalty for missing a Kyoto emission target. So Canada just announced in the middle of the Copenhagen conference, that it thought it's target no longer made sense, so it was forgetting it. Even the most cooperative countries are missing their Kyoto targets.
Even if Kyoto had specified a real penalty for failure to comply, the target was set 15 years in the future (from 1997 to 2012) and then it take a couple more before the final reporting is in. By then (as happened to Canada and others) emissions can be far off track. This means the penalty will be large and the excuses plentiful. The result will be penalties will be dropped or countries will drop out of the agreement.
4. 100+ Unique Commitments