If one is looking for clues from Warsaw as to the future of the U.N. climate change effort, probably the most telling is the phrase “nationally determined.”

Governments have set themselves the goal of a new global climate agreement in 2015. At the annual U.N. climate talks that wrapped up this weekend in Warsaw, they agreed on some of the steps they’ll take to get there.

The decision adopted in Warsaw invites all parties to “initiate or intensify domestic preparations for their intended nationally determined contributions,” and to “communicate them well in advance” of the 2015 meeting, set for December in Paris.  It also establishes a loose timeline: by the first quarter of 2015 for those parties “ready to do so.”

This is primarily a procedural decision, a way to move the process forward. The reason it was so difficult to reach was that parties fought incredibly hard either to inject or to avoid substantive framing that would begin to define the shape of the Paris accord.

By the time they were done cramming clauses into the ungainly sentence at the heart of the decision, the parties had managed essentially to preserve the vague but delicate balance they’d struck in launching this latest round of talks two years ago in Durban. The 2015 agreement will be “applicable to all,” but its legal character, and how developed and developing country obligations will be differentiated, remain undefined.

In one key respect, though, the decision does hint strongly at the nature of the future agreement.  Countries’ individual contributions to the agreement will be “nationally determined” – not negotiated, the way they were in the first round of the Kyoto Protocol. This reflects a growing acceptance that, to achieve broad participation, an agreement must give countries the flexibility to define their own commitments.

As I describe in a recent article in Nature, this self-determination of commitments is a defining characteristic of the new model of international climate governance that appears to be taking shape.

But many parties feel strongly that this “bottom up” feature must be coupled with “top down” elements that encourage greater ambition. The first step is getting countries to describe their intended contributions well ahead of Paris so they can assess one another’s offerings. The United States, among others, argues that if countries know their intentions will be subject to such “ex ante” scrutiny, they’re more likely to come forward with their best efforts.

The Warsaw decision speaks to this by encouraging those “ready to do so” to communicate their intended contributions by the first quarter of 2015. But it puts off until COP 20 in Lima, Peru, a year from now, any decision on exactly what kind of information parties should provide in laying out their proposals. Without detailed information – such as the assumptions behind the proposed targets, or the domestic measures backing them up – parties’ intentions will be hard to assess.

Nor does the Warsaw decision indicate how any such evaluation will take place. In the absence of any collective process to assess the adequacy and fairness of countries’ proposals, each party will presumably be conducting its own assessment, using whatever criteria it chooses. Rather than clarity, the result could be a confusing jumble of claims and counter-claims.

It is encouraging, on the one hand, that Warsaw reflects some convergence around a more flexible, and therefore politically more practical, approach allowing countries to better align their international commitments with their domestic needs and circumstances. But as a first test of whether this new model can deliver real ambition, the Warsaw outcome falls short.

Only time will tell whether it’s possible to marry “top down” and “bottom up” in a way that encourages a virtuous cycle of rising ambition – or whether Paris instead produces a dangerous do-as-you-please race to the bottom.

(See our summary of Warsaw outcomes.)