The immediate fate of the Kyoto Protocol may be the headline issue at the U.N. climate talks now underway in Durban, South Africa. But the real linchpin to any deal is not Kyoto – it’s whether or not parties can agree to any path beyond it.

What that may boil down to is whether governments are prepared to say that their goal, ultimately, is binding climate commitments. We believe they should.

For some time, we’ve argued that a preoccupation with “binding” has become more an obstacle than a means of progress. The reality is that key players including the United States and China are not prepared at this stage to take on binding commitments to reduce their emissions. Rather than arguing over that year after year, we should focus on strengthening the international climate framework step by step.

But that should not mean abandoning the notion of binding commitments. To the contrary, it’s important that countries affirmatively declare that their aim.

The fundamental reason is that climate change is so fundamental a challenge. It warrants nations’ firmest resolve – and commitment. Binding hardly means ironclad, but it represents a higher level of commitment, and for that reason is more likely to be honored. Each country will deliver its strongest effort only if it’s confident that others are contributing their fair share. In the long run, that’s best ensured by mutual and binding commitments.

The more immediate reason to set aim for a binding agreement is that without such a declaration, it may be impossible to make any progress at all here in Durban.

Most of the issues before parties are operational – agreeing on new rules and institutions to implement last year’s Cancún Agreements. One key step is launching a new Green Climate Fund to support mitigation and adaptation in developing countries. Another is strengthening the UNFCCC’s transparency system so countries report more fully and frequently on their actions and can better assess each other’s efforts.

However incremental they might be, such steps would represent progress nonetheless. But chances are slim that the operational package can be delivered without some resolution of the Kyoto question – and that, in turn, invokes the question of parties’ longer-term aims.

Here is why. With Kyoto’s initial emission targets expiring at the end of 2012, developing countries are insisting that developed countries keep the protocol alive by setting a new round of targets (the U.S. isn’t directly affected because it’s not a Kyoto party). While Japan, Canada and Russia refuse, Europe has said it may be prepared to enter a second commitment period (which in all likelihood would be politically rather than legally binding, effectively keeping Kyoto on life support). But Europe says it is willing to do so only on the condition that parties launch a new negotiation toward a binding post-2020 agreement.

Substantively, Europe’s goals are sound. But politically, it’s virtually impossible to imagine parties agreeing on an immediate process with so explicit a mandate. The United States insists that any such mandate be even more explicit – that it make clear that the ultimate agreement would be equally binding on all major economies, developed and developing. The developing, for their part, are not about to agree.

But even if parties can’t agree to launch a new round of negotiations right now, or on the parameters of a future treaty, can’t they at least agree that their ultimate aim is to produce a binding agreement?

The United States says no. It argues that such a vague declaration would be too open to conflicting interpretation, and that the U.S. should not sign on to something that it may not be able to deliver. It is right that a more general declaration is more ambiguous (hence its value in diplomacy). But by the same token, the very ambiguity of the statement would mean that the U.S. is not in any way boxed in.

By agreeing on the objective of binding outcomes, parties would simply be making a declaration of intent. All the core issues – what form of binding? on whom? when? – would remain to be negotiated. The United States, and every other party, would have ample opportunity to try to shape any resulting agreement before deciding whether it’s one it believes it can sell back home.

There is no saying we ever will achieve new binding climate commitments. Under the best circumstances, it will take time. But we certainly won’t achieve them unless we make it our goal. If others are prepared to do so, the United States should be too.

Elliot Diringer is Executive Vice President of C2ES.