Written by Jackson Ewing.

Over the past year, the United States and China forged a climate change partnership that would have been almost unthinkable not long ago. Not only have both countries committed to emissions reduction and sustainable energy goals of substantial ambition, they are pursuing those goals in concert.

This bilateral climate cooperation has been crucial to the UN climate summit in Paris and will continue to be so after any agreements are signed. Following years at loggerheads, the converging positions of the world’s two largest emitters are becoming invaluable components of future climate response actions.

So why is this happening?

A combination of domestic, bilateral and international forces help explain the transformation, and reveal its potential and continuing challenges.

China’s pollution crisis

In China, conventional pollution has moved environmental issues up the list of development priorities and made them part of the country’s core national strategic calculations.

The scale and scope of protests against air pollution and environmental decline – which by some measurements lead to 1.6 million deaths per year – are on the rise, and Chinese leadership is responding through rhetoric and practice.

President Xi called poor air quality Beijing’s “most prominent” challenge in 2014, while a top climate advisor deemed an acute pollution episode in the capital “unbearable.”

In response, the metrics for measuring local bureaucratic success and promotions through party ranks emphasize environmental performance more than ever before. Punitive measures against polluters are gaining strength, and efforts to transform energy systems are accelerating through rapid expansions in solar, wind and nuclear sectors.

Such measures have the corollary effect of reducing greenhouse gas emissions, which has changed the ways that Chinese leadership views international pressure to act on climate change.

Outside pressures to reduce China’s carbon emissions used to be viewed as anathema to the country’s development needs, and a distraction from its core business of wealth generation and societal development. They are now seen as opportunities for gaining partnerships, technical support and finance to help China transition toward a cleaner energy future. This includes expanding China’s manufacturing and export of clean-energy technologies, which have strong economic growth potential.

Xi’s China thus looks to the international climate arena for help addressing its domestic energy transition and pollution reduction goals. That the measures taken will also reduce climate risks is an added bonus.

US executive action

In the US, executive branch boldness has the Obama administration toeing the line of what is politically and legally tenable to advance some form of the environmentally progressive agenda the president campaigned on in 2008.

Frustrated with congressional intransigence and international inertia, the administration has opted for executive regulation at home and bilateral partnerships abroad. Obama’s Clean Power Plan places new emissions standards on power plants and vehicles, mandates and supports clean energy expansion, and seeks to cut energy waste and improve infrastructure.

On the first day of the Paris summit, the US announced Mission Innovation and officials touted the potential for technologies to lower emissions and “further encourage private-sector investment in clean energy innovation.” And in defending its Clean Power Plan, the White House emphasizes public health dividends, job creation, economic growth and long-term energy security.

Like China, US leadership sees these measures as being in the country’s long-term economic and strategic interests, and not merely as a ticket out of climate pariah status. Federal actions suggest this is not bluster, but a key part of the Obama administration’s vision for the country’s future.

Some welcome common ground

Bilaterally, American and Chinese diplomats have come to see climate change cooperation as low-hanging fruit in an agenda otherwise brimming with strategic tension. From currency markets and competitive free trade groupings to maritime navigation and the rise of China’s military, the relationship does not lack for wicked problems.

Climate change used to be just another avenue for strategic posturing, with China clinging to its status as a developing country with little culpability for the problem, and the US justifying its inflexibility through China’s inaction. Those days have passed, at least for now.

Beijing and Washington now see opportunity in the climate problem, and view it as a refreshingly non-zero sum game. They recently formed and now cofund the US-China Clean Energy Research Center, with a mandate extending through 2020, and are pursuing technical cooperation on issues from carbon capture and sequestration to sustainable urban infrastructure.

These connections feed into growing business ties, manifested most publicly through the annual US-China Clean Energy Forum. Such ties create incentives that are likely to keep climate cooperation from being a flash in the pan.

Global enablers and implications

This growing US-China alignment has accelerated because of changes in the direction of international climate change diplomacy.

UN-centric approaches have largely abandoned the holy grail of an encompassing and “binding” global agreement that covers an exhaustive range of climate issues. Disaggregated and largely voluntary approaches now rule the day, which allows the US and China to chart their own paths without feeling overly constrained or dictated to by international accords.

This shift also presents challenges. The US, China and their partners in Paris are searching for acceptable ways to transparently report and verify what emissions reductions are taking place where. This issue is taking on renewed urgency in the wake of China’s revelations that it underreported past coal consumption, and that it may resist including strong verification protocols in the Paris agreement.

The US insists upon enhanced international norms and practices around verification, which it sees as essential to prevent the approach of voluntary commitments from becoming a house of cards. The two countries’ ability to extend their cooperation to this issue will help determine the Paris outcome.

The US and China can likewise drive efforts to lubricate the gears of global commerce and reduce barriers to cooperation in clean energy sectors. Complex intellectual property and trade regulation challenges currently keep clean energy trade from reaching its full potential. These hurdles will not disappear overnight, but Paris is an appropriate forum for developing strategies to address them.

More fundamentally, the US and China are in a position to ensure that moves toward the flexible and voluntary do not devolve into reduced ambition and the shirking of loose commitments.

If these two economic and polluting behemoths show earnestness and ambition in Paris and beyond, the world is likely to follow.

Jackson Ewing is an Adjunct Research Fellow in International Relations at Nanyang Technological University. This article was first published on The Conversation and can be found here. Image credit: Wikipedia Commons