TOKYO -- Attempting to demonstrate her climate change credentials during the recent Democratic presidential debate, Hillary Clinton recalled a dramatic scene from six years ago.
"When we met in Copenhagen in 2009, President [Barack] Obama and I were hunting for the Chinese, going throughout this huge convention center, because we knew we had to get them to agree to something," the former secretary of state said.
The pair did manage to track down Chinese Premier Wen Jiabao, who was meeting with the leaders of India, Brazil and South Africa to discuss a united front among the emerging nations. But when the U.S. team sat down uninvited at the table, Chinese negotiator Xie Zhenhua burst into a tirade, wagging his finger at the U.S. president.
The Copenhagen climate change summit was, by most accounts, less successful than Clinton portrayed. What is significant, however, is how the tables have turned in the years since.
The biggest change is that China, under President Xi Jinping, is eager to show the world that it is intent on cutting carbon emissions. In Beijing last November, Xi, alongside Obama, announced a goal of capping rises in China's CO2 emissions by around 2030. It was the first time China explicitly laid out a peak emissions date, as well as the first time a developing country had made such a promise.
Recognizing climate change as one of the few areas the two economic giants can agree on, Obama responded by pledging to cut net greenhouse gas emissions 26-28% below 2005 levels by 2025.
This September, when Xi visited Obama in Washington, the two presidents reaffirmed their personal commitment to a successful climate agreement in Paris, where leaders are scheduled to meet for the annual Conference of the Parties. Xi said China plans to start a national emissions trading system by 2017.
There are several reasons for China's shift in policy. First, due to the slowdown of its economy, the country is easily on track to meet its 2030 target for peak emissions. There are signs that they might have already peaked: Coal consumption fell year-on-year in 2014 and does not seem likely to recover in 2015. If coal consumption did indeed top out in 2013, the peak of carbon emissions is probably not far behind.
"It takes zero to 10 years after the peak of coal consumption for carbon emissions to peak," said Jusen Asuka, professor of environmental policy at the Center for Northeast Asian Studies, at Japan's Tohoku University. Even in the slowest scenario, China's emissions will peak in 2023, a full seven years ahead of its stated goal. This gives China a strong hand to play when it sits down in Paris.
Second, it makes sense in terms of domestic politics to curb greenhouse gases. Chinese citizens are growing increasingly angry at rising levels of PM 2.5 pollution choking cities and threatening the health of their children.
China is also becoming a major supplier of renewable energy technology, such as solar and wind power. It has become the world's largest investor in clean energy, spending $89.5 billion, or 29% of the world total, in 2014. When exporting such products, it helps to be seen as a "green" country, rather than as the world's largest emitter of greenhouse gases, which China is.
Third, and perhaps most important to Xi, is the power struggle unfolding at home. The president's high-profile anti-corruption campaign has disproportionately targeted the oil faction, led by former security chief Zhou Yongkang, and the coal-rich Shanxi faction, which includes Ling Jihua, a former aide to Xi's predecessor Hu Jintao. Shifting away from fossil fuels deprives these rivals and their allies of the source of their power.
Obama, like most presidents nearing the end of their second term, is looking to add to his legacy, and he knows any agreement on climate change would look good in his trophy cabinet.
His party is on board. In the October debate, four out of five Democratic candidates raised climate change in their opening remarks. Former Maryland Gov. Martin O'Malley even talked of achieving 100% renewable energy by 2050.
Republican candidates, meanwhile, have scarcely mentioned climate change in the past two debates.
"The reduction of greenhouse gases is a zero sum game," says Asuka of Tohoku University. "Just like distributing water and food, if you get more, others get less. The politics of climate change negotiations is to try to make other countries bear more of the burden, as the world will only be able to emit a certain amount of carbon if we are to limit global warming to 2 C above preindustrial levels."
With room to make bolder pledges, China is expected to push Obama and European leaders to make further concessions at the Paris conference. Demonstrating on the world stage that China is a responsible "major" power is one of Xi's abiding ambitions.
Any agreement by the major economies, however, does not guarantee a meaningful result. India is much less enthusiastic than China about taking action, despite being the world's third-largest greenhouse gas emitter. Prime Minister Narendra Modi's government aims to reduce emissions per unit of gross domestic product by 33-35% by 2030 from 2005 levels. China, on the other hand, will aim for a 60-65% reduction.
In his Sept. 25 speech to the United Nations in New York, Modi alluded to an argument that has been made many times by emerging countries: Global warming was first caused by economic growth in developed countries, so it is unreasonable to expect emerging countries to hold back from pursuing growth due to global warming concerns.
The Indian government says it will promise to promote clean energy in exchange for having the U.N. accept emissions growth in the country. India aims to increase its non-fossil energy sources, such as nuclear and renewable energy, to 40% of total generation capacity by 2030, up from about 30% at present.
This arrangement would be convenient for Modi's "Make in India" campaign aimed at promoting manufacturing in the country. During his visits abroad, Modi has urged foreign companies to build photovoltaic power plants in India.
If successful, the prime minister's diplomatic strategy would help India secure the international community's blessing for further growth, even at the expense of higher emissions, and more foreign direct investment.
Nikkei staff writer Yuji Kuronuma in New Delhi contributed to this story.