GWEN IFILL: The climate talks over the next two weeks are expected to become a turning point in the global debate over addressing the causes of a rapidly warming planet.

HARI SREENIVASAN: Joining me now for further analysis of the climate change summit accord is Michael Levi. He is a senior fellow for energy and the environment at the Council on Foreign Relations here in New York.

So, the big question is, what does this mean for United States?

MICHAEL LEVI, Council on Foreign Relations: For the United States, this means that we are done with 20 years of fighting over the basic architecture of an international agreement, and if we flesh this out right, we will have a framework where we can have more insight into what other countries are doing, a regular process for pressing them to do more, and some greater certainty about the international structure that we are working within.

HARI SREENIVASAN: These are big compromises that are made between a lot of different countries.

What did the United States want that it didn't get?

MICHAEL LEVI: I think the United States would have liked essentially no distinction in the agreement between developed and developing countries.

This has been the fight for years. It would have liked exactly the same language about obligations for developed and developing countries on transparency, on updating their commitments, on what those commitments would look like, the basic elements of a deal.

They got a lot of those distinctions removed, but there are still bits and pieces of that in the agreement. And that's a sign that we will still continue to fight about those over the next year and in the years to come.

HARI SREENIVASAN: Now, you were in Paris. I heard there was actually not quite a scuffle, but a disagreement on the word, whether it should be shall or should, right, whether countries shall make these commitments and these reductions and economic changes or should.

I mean, now it's basically — it went towards should, and everything seems rather voluntary.

MICHAEL LEVI: Ultimately, all of these steps are voluntary.

We saw in the Kyoto protocol that we had mandatory requirements, legally binding requirements that countries didn't adhere to anyhow. So, I think we can get overly obsessed with should vs. shall.

The critical distinction that the United States was focused on there is that shall would have sent the agreement to the Senate for ratification, where it would have died, and should allows it to actually exist.

So, better to have an agreement that is not absolutely perfect, but that exists, than one that you love, but can never fly.

HARI SREENIVASAN: So, what are the commitments that the United States has to make now, even though it doesn't have to go to Congress? I mean, will we have to create some laws to say, here is how we are going to decrease our emissions?

MICHAEL LEVI: So, there are two basic elements here.

First, the United States has made a pledge to reduce its emissions by 26 to 28 percent below their 2005 levels by 2025. Without new policies, we are not going to get there. Whether we need new laws or just new regulations under existing law remains to be determined and will depend not only on politics, but on how technology and the economy evolves.

So, there's that piece on U.S. emissions. The other is that the agreement is going to include rules for transparency, for review of countries' efforts, for updating of countries efforts. The details of those could matter a lot.

And it will be not only China and India and others who are scrutinized, but the United States that is scrutinized. So, U.S. negotiators will be looking to nail that down.

HARI SREENIVASAN: And every five years, we sort of have to say, here is what we're going to try to do. And everything else can see this, and we can see what everyone else is doing.

MICHAEL LEVI: That's right.

So, we have said, here's what we're going to do between now and 2025. Some time between today and 2020, we will extend that to a 2030 goal to align it with other countries. And then everyone will participate in this regular five-year process.

What worked in this past year was, the spotlight Paris shone got countries to actually go work on serious policies that could reduce emissions. And the hope is that, if you do that every five years, you can mobilize that same kind of political focus.

And that's the fundamental thing here, is, this is a recognition this is not a technical, legal effort.

HARI SREENIVASAN: Yes.

MICHAEL LEVI: It's about driving better politics that enable better policy on climate change.

HARI SREENIVASAN: All right, Michael Levi from the Council on Foreign Relations, thanks so much for joining us.

MICHAEL LEVI: My pleasure.