Because little action was taken to combat climate change at the United Nations conference last December in Copenhagen, a panel of experts speaking at Yale Law School Tuesday afternoon said there needs to be an effective strategy to ensure fast action on the issue.

The panel, which was moderated by Yale Law School professor Douglas Kysar and featured Caleb Christopher, the attorney to the UN Mission to the Marshall Islands; Natural Resources Defense Council policy director David Doniger; Suffolk University professor Steven Ferrey; and Dan Esty LAW ’86, a professor at both Yale Law School and Yale School of Forestry and Environmental Studies professor, discussed the present and future of international climate change regulation in front of an audience of about 40 at the Law School. While the panelists agreed on the need for urgent action, each expert focused on different aspects of the issue.

Esty said while countries like Mexico, Brazil and South Africa stood ready to take action after Copenhagen, the United States’ leadership is an integral part in ensuring progress.

“You cannot get a deal done if the U.S. does not put a deal on the table,” Esty said.

One way to solve the problem, Esty said, is by incorporating a federal tax for greenhouse gas emissions, which he referred to as the “harm charge.” Esty also said that there needs to be a shift towards the use of natural gas in the United States, noting that countries which have done have managed to lower their emissions. He used Britain as an example.

When asked by an audience member about the Mexico City climate change conference later this year, Esty said he would not count on anything being decided, although he believed that China would step up because cutting greenhouse gas emissions is not only about global warming, but also part of the country’s air pollution problem.

Doniger, who called himself as an optimist, spoke about what Copenhagen managed to achieve, despite the general conclusion that it was a failure. Doniger stated that a lot of important steps have been taken; countries like South Africa, China and North Korea have commited to reduce emissions, which would have been unimaginable a few years ago.

Ferrey, who is an adviser on privatization for the World Bank, emphasized the role that India and China play in reducing carbon dioxide emissions. In the past 15 years, China‘s carbon dioxide emissions have doubled, Ferrey said. He added that even if all other countries in the world were to reduce their emission levels, without China, it would still be hard to achieve the targets.

Christopher focused on the urgent need for action, especially for small nations. Although the Pacific nation of the Marshall Islands was one of the most vocal supporters of the Copenhagen conference, they need the help of large nations, he said.

“We need to find something achievable, not just empty words. We can’t stay in the cycle of workshops,” Christopher said.

Nate Freeman LAW ’11, who was in the audience, said he agreed with Esty’s tax proposal and the United States could not rely on a cap-and-trade system of reducing greenhouse gas because this type of regulation is open to abuse.

“Internationally, everybody has to be on board, and domestically, there needs to be a way to make people pay for the harm they cause,” he said.

At the Copenhagen conference, the United States promised to raise $100 billion annually by 2020 in order to help developing countries in coping with climate change.