The Obama administration is in the final stretch of enacting the goals of the president's broad climate change agenda with an international meeting in Rwanda next week to hash out a major deal among 197 countries on phasing out refrigerant chemicals used in air conditioners.

"So you can see, countries are ready for action, and the time to get it done is now," said Environmental Protection Agency Administrator Gina McCarthy in a media call late Wednesday, noting last month's commitment by 100 countries at the United Nations to sign onto an agreement in Kigali.

"We are on a roll, folks," she added. "We have done a great job here under this president's leadership, and it's not going to stop now."

Agreement in Kigali to phase out the chemicals, known as hydrofluorocarbons, or HFCs, could reduce global warming by half of a degree Celsius by 2100, McCarthy noted.

The adoption of the agreement also will be a significant step in achieving the goal's of last year's climate change agreement in Paris, which seeks to keep global temperatures from rising above 2 degrees Celsius in the coming decades, she said.

"This is one of the best steps we can take to fight climate change and continue to the Paris agreement goal," she said.

The Paris Agreement reached a major milestone Wednesday when it achieved the threshold requirements for it to take effect by early next month.

Nevertheless, McCarthy conceded that there are some "challenges" going into next week's meeting in Africa, noting that developing nations are seeking more assurances that they will have access to HFC alternatives as the phaseout occurs. They also want to ensure access to adequate funding from developed nations and private sources in helping to reach the goals.

"We have also listened to developing countries' concerns, and we know we need to make sure that nations, especially in the developing world, have the funding and support they need to adopt safer alternatives to HFCs," she said. India has been vocal about the need for adequate funding for the agreement to move ahead.

McCarthy said she is aware of India's concerns, but the Obama administration and the majority of countries are confident they can work out the issues next week to enact an "aggressive" program.

The HFC deal is being hashed out under the Montreal Protocol, which was established in the 1980s in response to the erosion of the ozone layer by chemicals found in ordinary chemical sprays, such as freon, which were phased out and replaced by HFCs.

Now, scientists have found HFCs to be a harmful greenhouse gas that is causing the Earth to warm, resulting in more drought and flooding.

McCarthy emphasized the protocol's existing funding mechanism to downplay concerns that emerging economies may back out without adequate support. She said the mechanism would help the countries adopt new technologies to replace HFC use with safer alternatives and greater energy efficiency.

In addition, private donors at the U.N. General Assembly last month announced $80 million to help spur the transition in developing nations to HFC alternatives, which are crucial to the success of the phaseout, McCarthy said.

The global phaseout of HFCs dovetails with EPA's recent implementation of two regulations to phase out the refrigerants in the U.S., McCarthy noted.

"So, we are incredibly well positioned for success in Kigali," McCarthy said. "We have the tools and technologies we need, the proven mechanisms of the Montreal Protocol and the collective commitment and the culture of collaboration to adopt an ambitious HFC phasedown amendment."