The U.N. climate negotiations often have the feel of a multi-ring circus – several negotiating bodies, each including virtually all the same parties, wrangle over different issues in different rooms. You have the COP, the CMP, the SBI, the SBSTA, the AWG-KP, the AWG-LCA, not to mention the various contact groups, informals, and informal informals.

So when the talks resume next week in Bonn, Germany, it will be a rare moment. For the first time since the 1997 conference that produced the Kyoto Protocol, parties will be devoting their entire time to a single negotiating body. Its aim: a comprehensive new agreement in 2015 to start in 2020.

One might hope this singular focus will allow something of a fresh start. And judging from their written submissions going into the Bonn talks, some parties are indeed bringing new perspectives. Others, meantime, are recycling old ideas. And some seem to envision a new agreement strikingly similar to what we’ve already got.

Parties will be meeting as the Ad Hoc Working Group on the Durban Platform on Enhanced Action, so named because it was launched at COP 17 in Durban, South Africa, in 2011. The ADP, as it’s been dubbed, has so far moved very slowly. Parties first had to wrap up business under the AWG-LCA and AWG-KP, including a second round of Kyoto targets, which they managed at COP 18 in Doha, Qatar, late last year.

The ADP’s purpose is to “develop a protocol, another legal instrument or a legal outcome under the Convention applicable to all Parties.” This brief but ambiguous mandate implies a host of issues and options. As they head into Bonn, parties are starting to offer up more concrete ideas on just what kind of agreement they foresee.

Some are remarkably familiar – because either we’ve heard them before or they already exist.

China’s view falls into the latter category. The United States and others interpreted “applicable to all” as dissolving the historic dichotomy under the climate Convention between developed and developing countries. However, China (like India) explicitly rejects revising the Annex I list, negotiated in 1992, that defines which countries are which.

For developed countries, China sees legally-binding economy-wide emission reduction targets, as in Kyoto. Developing countries would take “diversified enhanced mitigation actions…supported and enabled by adequate finance, technology and capacity building support from developed countries.”

The United States proposes a radically different approach: It’s OK leaving Annex I as is, but the United States doesn’t see applying it to the new agreement.

In fact, departing from the model it advocated ahead of the 2009 Copenhagen conference (quantified reductions for developed countries, and quantified “actions” for developing countries with “greater responsibility or capability”), the United States now envisions an agreement with no categories at all.

In the new U.S. view, parties “define their own mitigation contributions, taking into account national circumstances, capacity, and other factors that they consider relevant.”  Rather than the old binary division, there would be a natural spectrum – “self-identification of measures would result in self-differentiation.”

Most ideas from other parties lie somewhere along a rough spectrum between the United States’ bottom-up “self-identification” model and China’s Kyoto-redux.

Showing that some developing countries are not as wed to past practice, an alliance of Latin American and Caribbean states notes that while the Convention’s principles “are enduring, they are also dynamic.” Australia and the European Union propose as the United State once did that all major economies have economy-wide emission targets. India suggests that a new agreement’s “legal force” could derive from domestic, not international, law. Ethiopia proposes keeping the Annex I/non-Annex I distinction but revising the lists every five years based on per capita emissions. Singapore rejects formulaic approaches as unworkable.

Some common themes emerge. One is that an agreement must be flexible to accommodate very different national circumstances (though not all want it as flexible as the U.S.). Another is that an agreement must be dynamic, able to evolve as countries’ circumstances change.

In a sign that parties’ expectations have tempered since the blowup in Copenhagen, some openly argue that the agreement must be dynamic in part because the initial round of commitments won’t be strong enough. We’ll need a “robust mechanism,” says South Korea, to raise ambition over time.