Jimena Leiva Roesch was among the thousands applauding in a crowded conference center outside Paris last week, when a landmark new climate change agreement was struck. The International Peace Institute Policy Analyst and former Guatemalan climate negotiator said there was a definite sense of momentum in the air, as countries claimed ownership over their own plans for reducing emissions.

“I think it was a success on many fronts,” Ms. Leiva Roesch said. “In the United Nations Framework Climate Convention there are 195 countries, and usually what you get are watered-down decisions that cater to the lowest common denominator, with very little ambition. This time around the agreement reached in Paris shows a high degree of ambition.”

Speaking with IPI Senior Adviser John Hirsch, she said the agreement secured the long-term goal of decarbonizing the global economy in the second half of the century. It also linked the goals of mitigating emissions and eradicating poverty.

“It needs to be a win-win solution,” Ms. Leiva Roesch said. “We can’t focus only on reducing emissions if we’re not providing access for the poorest to sustainable energy.”

This interview has been edited for clarity and length.

The Paris climate change conference has been widely hailed a success, in contrast to the perceived failure of the 2009 Copenhagen summit. Do you agree with that assessment, and on what basis?

I think it was a success on many fronts. In the UN Framework Climate Convention there are 195 countries and usually what you get are watered-down decisions that cater to the lowest common denominator, with very little ambition. This time around the agreement reached in Paris shows a high degree of ambition.

First, it secures a long-term goal. It communicates that by the second half of the century we need to reduce emissions and start to undertake rapid reductions, so that by the end of the century we will be living in a different energy system. Then it has reference to the 1.5/2°C target, which is, in a way, the most important aspect: that all the climate change plans that have been put forward need to combine to limit the global average temperature rise to below 2°C. Recent studies show that if we only have these plans and we don’t scale up ambition every five years, it won’t be enough, and we would be looking at 2.7°C, but the agreement specifically mentions that countries will submit a more ambitious climate plan every five years that will increase their contributions.

The other part is the finance. Developed countries are committing to the $100 billion USD goal in investments, which was put forward in Copenhagen and was honored in Paris. In the text there’s also an agreement that by 2025 that goal will be revised upwards.

And a third point is differentiation. The agreement certainly recognizes that developed countries should take the lead in the fight against climate change and that’s really important given their historic responsibility. It also supports the ambition already shown by China, Brazil, and India that they are responsible partners.

About a year ago, US President Barack Obama and Chinese President Xi Jinping met in China and made a pledge to work together to reduce global greenhouse gas emissions. How important do you think that particular meeting and the role of those two countries was to the achievement of the climate change agreement in Paris?

Even during the final hours of the negotiations and the final few days of the meetings, [US Secretary of State] Kerry was there, and also his counterparts in China and India. Having that leadership there and being keenly aware of the issues, and not only sending experts, was really a game changer. Kerry referred to the nuclear deal in Iran and how difficult it had been to get an ambitious outcome with only six nations. So for him it was personally very rewarding to have an ambitious agreement that was elaborated with over 190 voices. The China and US agreement was essential, and the agreement between the French and the Chinese also. All of those were little pieces that really helped bring about the final deal.

The other question is India. Prime Minister Modi faces a very significant challenge because a very large percentage of the population is living in poverty or barely above it. Do you think India can keep the promises it has made, and is Modi going to face a lot of difficulties in the next year or two that will impede his abilities to carry out these commitments?

India presented its national climate plan on October 2^nd and it is a step forward. In the negotiations they stressed that this climate agreement could not be viewed in isolation, particularly when their biggest challenge is poverty eradication as you mentioned, and sustainable development. What India did, and I think it was very good in the end, was to connect efforts to reduce greenhouse gas emissions with efforts for poverty eradication, for sustainable development, so the long-term goal on mitigation is now linked with these.

It needs to be a win-win solution. We can’t focus only on reducing emissions if we’re not providing access for the poorest to sustainable energy. India’s voice resonated with a lot of other developing countries that had similar views and in the end it became another positive outcome, because it reinforced the idea that climate change action is not bad for development, and vice versa.

This was obviously a conference of governments, but there are also a lot of economic interests involved. In the past there has been a lot of resistance to promoting sustainable energy policies, because of all the investment involved in oil and gas and coal. What is your view of the role the private sector played in facilitating the climate change agreement?

The resistance was still there. There were still a few voices that were dissenting and did not want to change the status quo. The difference was that there were a lot more positive voices, even in the private sector, wanting to start veering away from fossil fuels. I think that the climate summit that the UN Secretary-General convened last year was a tipping point, because it attracted a lot of private sector engagement. Subsequent to this, in Paris there was a whole event focused on the private sector. Civil society action, including the People’s Climate March, also added positive pressure to the negotiations.

It has helped that really big investors and big companies have come out in favor of transforming the economy toward renewable energy, so now those lonely voices have been joined by others. President Hollande said at the start of the meeting that France has lived many revolutions, and now we are living the climate revolution. This revolution is not possible if you don’t have a private sector that is engaged.

In American terms, this agreement is not a treaty because President Obama felt it was better to have an agreement that would not have to be submitted to the US Senate for ratification. But the question which arises is how will this agreement be carried out, absent a formal enforcement process?

What has been really incredible is that 188 countries submitted their climate plans before Paris. This was an unprecedented success. No one thought that every country would voluntarily put forward a plan to limit greenhouse gas emissions, so that already proves that the kind of bottom-up approach of these national plans works.

The problem was how we were going to sum up all of them; what is the aggregate effect of all of the intended contributions together? The agreement does address that. There will be a global stock-take that will measure the aggregate effect, and this will need to see if we are meeting the 1.5/2°C target. The fact we have the targets, and we have the stock-take, and we have a cyclical review every five years, those three components make the agreement ambitious and way beyond what we had before in Kyoto.

So you’re optimistic that this climate plan will be carried out and will make a significant difference in reducing greenhouse gas emissions?

The agreement was greeted with an amazing standing ovation. There is definitely a momentum that has been gathered by the ownership of the process, ownership of the text, and the greater awareness that if we don’t come together to combat climate change, other development issues will be substantially hampered. Without action on climate change, we will revert and have more poverty and the 2030 agenda would simply not be achieved. There is simply is too much stake and we have to be optimistic.