At the U.N. climate talks in Baku, Azerbaijan, negotiators at the very last moment struck a deal.

Wealthy nations have pledged $300 billion a year by 2035 to help developing countries deal with the impacts of climate change and to help their transition to cleaner energy.

While that pledge is stepped up from previous pledges, it is nowhere near the estimated $1 trillion a year that many experts and analysts say is needed.

While some have called this deal woefully inadequate, the COP 29 president, Mukhtar Babayev, defended its accomplishments.

MUKHTAR BABAYEV, President, COP 29: This was the hardest task the multilateral climate process has ever attempted.

We had many difficult conversations.

We never stopped pulling you together.

We pushed you to reach for the highest possible ambition.

With this breakthrough, the Baku finance goal will turn billions into trillions over the next decade.

WILLIAM BRANGHAM: So for more on this summit, we are joined again by Manish Bapna.

He's the president and CEO of the NRDC, the Natural Resources Defense Council.

Manish, so nice to have you back.

What is your initial takeaway from this summit?

MANISH BAPNA, President and CEO, Natural Resources Defense Council: Well it is a down payment.

What we saw from this deal, which was largely about finance, is that it represented what was possible in a geopolitically complicated world today, not necessarily what ultimately will be needed.

So the 300 billion that you spoke about is going to help developing countries make the shift to clean energy.

It's going to help them adapt to extreme weather that we're seeing happening today.

But most independent experts say we need $1.3 trillion.

So a lot of the hard work that still is left is, how do we move from the $300 billion to the $1.3 trillion over the coming years?

WILLIAM BRANGHAM: Because it is in that chasm that all the outrage exists coming out of Baku.

I mean, as you know, these nations argue, we did nothing to cause this problem, and yet we are suffering the worst impacts, the famines, the droughts, the things that are made worse by climate change.

And they're saying we have to foot the bill for this and this comes nowhere near what we are owed for this.

I want to play one little bit of sound.

This is the climate negotiator, one of them, from Panama.

Here's what he had to say.

JUAN CARLOS MONTERREY GOMEZ, Climate Envoy, Panama: They throw text at us at the last minute, shove it down our throat, and then for the sake of multilateralism we always have to accept it and take it.

Otherwise.

The climate mechanisms will go into a horrible down-spiral.

And no one needs that.

This is the only space that we have to negotiate and to work towards our common goals.

We accepted the text because we could not leave Baku without a text, but we're not satisfied whatsoever.

WILLIAM BRANGHAM: Not satisfied at all.

Well, what do you make of that concern?

MANISH BAPNA: I hear that point of view.

I really empathize with that point of view.

When you look at the United States, the E.U., Russia and China, they represent roughly 60 percent of global emissions.

You look at the 10 most vulnerable countries in the world on climate, less than 1 percent of emissions.

So this is environmental injustice on a global scale.

When COVID took place, the rich world was able to mobilize $20 trillion overnight.

So developing countries are asking, why not?

Why can't we get more money?

And the arguments for why the rich world should give the money are compelling, strong economic reasons, security reasons, and justice reasons.

Clean energy is a $2 trillion market this year.

We are moving from the dirty energy of the past to the clean energy of the future.

Important to make that commitment.

If we don't, we're going to see increasing climate impacts, increasing conflict, increasing displacement.

It's an investment in our security.

And, as I said, from a global justice standpoint, those that are bearing the brunt of the costs did the least to contribute to the problem.

WILLIAM BRANGHAM: So those are the arguments for greater contributions to funds like this.

What is the argument that the Western nations, the E.U., the Americas of the world, put forward to say why this is too much money to spend or inappropriate money to spend?

MANISH BAPNA: Well, part of the argument is that it's a lot and it represents a tripling of the commitment that was made back in 2009 by Secretary Hillary Clinton when she was secretary of state, when it was $100 billion for 2020.

So part of it is, how you move from $100 billion to $300 billion is not easy.

It requires both governments, rich governments, rich country governments to give money to the developing world.

But it also means mobilizing international institutions like the World Bank, the Asian Development Bank.

It is also further complicated by the geopolitical moment we're in, where conflicts all around the world are taking resources and a recognition that, here in the United States, the Trump administration, future Trump administration is unlikely to provide support.

So other countries are going to have to step up even more in the short run.

And so that is what is making this particular moment complicated to get to a higher number.

WILLIAM BRANGHAM: Some people have argued that this whole, the way COP is run, which is -- has every single nation involved, close to 200 nations, everyone has to agree on every line and every sentence of every agreement, and that that becomes an unwieldy morass that never gets substantive things done.

Do you share that concern?

MANISH BAPNA: Part of that critique is absolutely true.

I mean, at one level, it is incredible that the international community, 190 countries, can get behind a single document about how to shift from fossil to clean energy.

But that level of unanimity that is required means any single country can derail process.

And we see that happening year after year.

So I do believe we need to see about some more fundamental reform in the process around international climate negotiations, so that we can actually get global agreements that are commensurate with the challenge.

The problem we're facing at the moment is not direction to travel.

I think there's an increasing recognition that clean energy, that tackling climate is part of the future.

The problem we're facing is pace, speed.

How do we move faster?

And that is where we can't let individual countries get in the way of what the vast majority of countries want to do.

WILLIAM BRANGHAM: Manish Bapna of the NRDC, always great to see you.

Thank you.

MANISH BAPNA: Delighted to be here.

Thank you.