The United States of America and China have signed an ambitious agreement designed to limit greenhouse gas emissions ahead of next year’s summit.

President Obama announced that the US would be moving much more aggressively on reducing their carbon footprint. The Chinese President, Xi Jinping, agreed to cap China’s emissions in the future, a truly striking move from a nation which has thus far been unwilling to acknowledge its role in greenhouse gases or box itself into a corner on climate change.

“This is a major milestone in the US-China relationship,” Obama said, with Xi at his side. “It shows what’s possible when we work together on an urgent global challenge.”

This unexpected declaration comes on the last day of President Obama’s visit to China and shows that the time may be right for the world’s biggest polluters to start working to bring down their output. This united front also may present a problem to developing nations, who have thus far walled themselves off from responsibility on pollution due to the two largest polluters not having an agreement to reduce their own emissions.

The problem however comes when trying to decide how feasible either of these positions are, especially for America with the Republicans in the ascendency unwilling to confront climate change as a problem.

It was a campaign promise by President Obama to reduce greenhouse gas emissions when he first ran for president and this may represent a return to his roots as a candidate. The US therefore set a new target to reduce its emissions of heat-trapping gases by 26 percent to 28 percent by 2025, compared with 2005 levels. That’s a sharp increase from earlier in Obama’s presidency, when he pledged to cut emissions by 17 percent by 2020.

China, whose emissions are still growing as it builds more coal plants, didn’t commit to cut emissions by a specific amount. Rather, Xi set a target for China’s emission to peak by 2030, or earlier if possible. He also pledged to increase the share of energy that China will derive from sources other than fossil fuels. This search for alternative fuel sources may end up being very important for China as their coal mines are what cause the tremendously damaging smog over major cities. The coal mining industry has also led to a large amount of death due to cave-ins and as ever damage to the lungs of miners.

“This is, in my view, the most important bilateral climate announcement ever,” said David Sandalow, formerly a top environmental official at the White House and the Energy Department. “It sends the signal the two largest emitters in the world are working together to address this problem.”

This new policy presented by Obama may serve as the American contribution to the ever increasingly list of agreements set to go into the treaty negotiations in Paris next year. The US has become very aggressive on its pollution policies in hopes of convincing other nations to become involved in their agreement and hopefully reduce their pollution outputs.

For China this represents a major turning point in their political history. They are reacting now as a superpower would when confronted with a problem of this magnitude; it is now China’s responsibility too. China accounts for around 30% of global emissions, but has only gotten serious in recent years as the large-scale impact on health and quality of life in China has come into focus.

Al Gore, the former vice president and a leading advocate for limiting climate change, called the announcement “a major step forward in the global effort to solve the climate crisis.” He did however say more will be required, “including a global agreement from all nations, but these actions demonstrate a serious commitment by the top two global polluters.”

The Republicans in Congress however are looking for a way to thwart this idea in its infancy. “This unrealistic plan, that the president would dump on his successor, would ensure higher utility rates and far fewer jobs,” said incoming Senate Majority Leader Mitch McConnell.

Despite opposition, which was bound to come, from the Republicans this is not a problem which can be ignored. The United States needs to commit itself to a large reduction in greenhouse gas outputs if it hopes to have any sort of moral authority when asking for it from other countries. This agreement may represent the first compromise which would allow East and West to find a real solution on the environmental impact of greenhouse gases. I hope this agreement stands and that the US can work towards making it a reality. It will leave a world not full of more jobs or more money for our children, but it will leave a world which will be clean, where it will be safe to go outside, where the next generation can leave their mark.