On the heels of a historic agreement between the U.S. and China to phase down super greenhouse gases known as hydrofluorocarbons using the Montreal Protocol, India now has an opportunity to join the other leaders to secure the most immediate and significant climate protection available to the world through 2020.

More than 110 countries have expressed support, including Russia, South Africa and the EU 27, as well as the U.S., Canada and Mexico, many island states, and other developing nations, but India’s support will be important for a swift conclusion. Secretary of State John Kerry will be in India next week and should make securing India’s support a priority.

President Barack Obama and his administration have embraced the phase-down of climate-damaging HFCs under the Montreal Protocol, making the HFC agreement with China’s President Xi Jinping a priority outcome of their first summit, along with progress addressing the threat from North Korea. Putting climate protection as one of their top priorities is historic and may turn out to be the most important development yet to reduce the world’s climate threat.

The Obama-Xi agreement builds on Kerry’s earlier efforts in China to form a climate task force. Secretary Kerry also made the HFC phase-down under the Montreal Protocol a priority of his participation in the Arctic Council summit last month, bringing Russia into the growing consensus. This follows the success of former Secretary of State Hillary Rodham Clinton who made phasing down HFCs a key part of the Rio+20 summit declaration, supported by more than 100 heads of state. Clinton also made reductions of HFCs part of the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants, which she launched in February 2012.

India now has the chance to join the U.S. and China as a leader to complete the consensus needed to amend the Montreal Protocol in October. Reluctance risks leaving India on the sidelines as China and the U.S. develop their special relationship.

Historically, India has been a key nation in the Montreal Protocol throughout the 25 years of its operation, which includes phasing out nearly 100 chemicals similar to HFCs, by nearly 100 percent. This has put the stratospheric ozone layer on the path to recovery by midcentury and provided significant climate mitigation as well.

India was the chief advocate for ensuring the Montreal Protocol fully implements the principle of “common but differentiated responsibilities,” when their team insisted on a dedicated funding mechanism to pay full incremental costs for developing countries to shift to safer substitutes. The fund is one reason the Montreal Protocol is considered a fair and equitable treaty.

Phasing out HFCs under the Montreal Protocol will cut the equivalent of 100 billion tonnes of CO2, 10 times more than the Kyoto Protocol to date. This will avoid 0.5 degrees Celsius of warming by the end of the century and make a major contribution to keeping temperature increases to less than 2 degrees Celsius above pre-Industrial levels.

Phasing down HFCs also will catalyze energy efficiency improvement in the air conditioners, refrigerators and other equipment that use HFCs during the transition to superior substitutes, which will significantly reduce CO2 emissions as well as HFCs. In the past, the transitions have been associated with efficiency gains of up to 30 percent. In India, where a high percentage of domestic power generation is for air conditioning and refrigeration, improvements in efficiency will significantly reduce the demand for electricity.

In the U.S., the HFC amendment will provide important progress toward the U.S. pledge in Copenhagen, Denmark, to reduce emissions 17 percent below 2005 levels by 2020, providing nearly a quarter of what still has to be done to meet this target. Congressional ratification will be needed to approve the amendment, but the Montreal Protocol has enjoyed strong bipartisan support since it was first negotiated under President Ronald Reagan, not least because the cost of phasing out these chemicals has been extremely low. Phasing out HFCs would cost on the order of 5 cents to 10 cents per ton of CO2 equivalent, far lower than many mitigation options.

Leadership from India to support the HFC agreement would signal that the world has entered a new period where the largest emitters, both developed and developing, are working side by side to address our most critical climate issues.

While efforts to cut CO2 and other climate pollutants will continue to be a challenge, future generations will view an HFC agreement as a turning point in climate protection, when the world finally began to take effective action.

Durwood Zaelke is founder and president of the Institute for Governance & Sustainable Development in Washington and Geneva. Paul Bledsoe is a senior fellow on energy and climate at the German Marshall Fund of the United States, and was communications director of the White House Climate Change Task Force under President Bill Clinton.