International leaders ended 2015 with what many consider to be a major win for climate change, as close to 200 countries struck a deal in Paris. Some, like the former European Commission for Climate Action Connie Hedegaard, consider it a paradigm-shifting moment and calls to renegotiate it “ridiculously absurd.” Hedegaard played a pivotal role in the Copenhagen climate conference in 2009 and has remained an important figure in the international climate scene ever since.

“What has been the nightmare, you could say, about all of these climate negotiations is that it has been a proxy for a much bigger battle to take the world from the north-south paradigm of the 20th century in the 1970s and onward to a new 21st century paradigm of mutual interdependency. That is what is reflected in the Paris agreement. That’s why I think it was a real step being taken,” Hedegaard said at a June 1 event hosted by EPIC.

Hedegaard continued saying that whether the Paris accord achieves more will depend a lot on the steps moving forward.

“And, it’s not the time for anyone in the U.S. to start threatening to renegotiate this,” she said. “If you’ve been close to this process, it’s almost ridiculously absurd to hint at renegotiating. I hope that will never be the case, but just to talk about it in that way is actually damaging for the reputation of the United States.”

In a conversation with EPIC’s Senior Fellow and former White House National Security Director for International Climate Policy Pete Ogden, Hedegaard explained why she believes negotiators were able to strike a deal in Paris.

First, she said important lessons were learned in Copenhagen in 2009. There, the organizers where able to engage top governmental leaders and not just environment ministers for the first time. That was important, she said. But, equally important was the lesson to not bring these leaders in at the end. She explained that countries would come in with a mandate, and if they knew their country’s leader would be there at the end of the conference they didn’t dare to depart from the mandate. On the other hand, by having leaders there at the start of the conference, as they were in Paris, they were able to “set the signal to the negotiators” that they needed to find agreement.

A second reason why Paris was so successful, Hedegaard believes, was a matter of timing. For many years, the U.S. and China played, what she calls, the “after you, sir” game, where neither country would budge unless the other country also made a move. Then, two things happened: President Obama came into the White House and was resolved to take action, and political and economic circumstances in China were such that it made sense to take action.

“Due to their pollution getting worse, they were forced to internally, for domestic and political reasons, address these kinds of issues in a much more radical way,” Hedegaard said. “And they saw how they could do it. They saw with solar how they could develop and take the market very fast.”

Hedegaard considers the public announcement made by the U.S. and China ahead of the talks that set their targets a pivotal moment. That, combined with the realization worldwide that climate change was actually occurring, made the moment right for a global accord.

The deal may now be in place, but the work is far from over, Hedegaard said. She noted that countries will need to prove that they are working towards their commitments. And, for developing countries to hold up their side of the agreement they will be relying on developed countries to deliver on their finance pledges.

“If you’re a developing country, what really matters is, can you jump a generation or two of technology or not?’ Hedegaard said, acknowledging that as a smart way of thinking—go straight to the best technologies. “That comes with an additional cost of 10-20 percent. That is where global climate financing comes in.”

But, Hedegaard said, while developing countries insist public climate financing is better than private money, developed countries believe the opposite and for good reason: a village waiting to gain access to electricity is going to be waiting a lot longer if that financing needs to go through all of the bureaucracy of a public financing system.

“If we go in there and use the money intelligently to get more private investment in developing countries that would bring the fastest changes in ways developing countries could see there’s also something in it for me,” Hedegaard said, calling that the “litmus test.”

Strategically, it will be important for Europe, North America, Australia, Japan—all of the countries that are seen as having “started this mess in the first place”—to lead the pack in the 21st century.

Hedegaard said, “We will be judged by a lot of developing countries by whether we are actually accountable. Can you count on us to deliver what we pledged?”