WASHINGTON • Six years after a fiasco in Copenhagen and a year before he leaves office, a Paris summit offers US President Barack Obama the chance to make his mark in the fight against climate change.
In December 2009, he left the Danish capital after signing a hastily issued statement by leaders hoping to save face.
His hair now greying, Mr Obama will arrive on Monday in Paris against a very different backdrop.
A deal to slow global warming seems to be within reach, even if it is less ambitious and less far reaching than first hoped.
"Paris is a legacy moment for President Obama, a capstone for all he has done domestically to move the United States into a more sensible and inspiring place on climate change," said Ms Jennifer Morgan of the World Resources Institute.
"We are in a much different position on climate than we were six years ago, with renewable energy now providing a low-carbon energy option for those without electricity around the world, and people feeling the impacts of climate change in their daily lives."
Still, it is highly unlikely that the Paris targets will be able to limit global warming to 2 deg C above pre-industrial levels, the long-stated goal.
"Let's stipulate right now, whatever various country targets are, it's still going to fall short of what the science requires," Mr Obama said in an interview with Rolling Stone magazine. "For us to be able to get the basic architecture in place with aggressive enough targets from the major emitters that the smaller countries say, 'This is serious' - that will be a success."
After the Nov 13 terror attacks in Paris, Mr Obama was among the first to say he would stick to his plans to attend the climate talks on Monday. Some 150 other leaders are also expected to be there. Only a few of them, including German Chancellor Angela Merkel, were around to remember what Mr Obama has called the "disorganised mess" of Copenhagen.
This time, the ground has been well prepared in advance.
A year ago, Mr Obama inked a deal with the planet's other major polluter, China. For the first time, Beijing made a firm promise that greenhouse gases would peak by 2030, sending a signal to the rest of the world. Tellingly, Mr Obama's first meeting when he lands in Paris on Monday will be with Chinese President Xi Jinping.
The negotiations in Paris will also be different - each nation is setting its own targets rather than having binding targets imposed upon all the countries.
That also means the agreement will not be a formal treaty, which in the US would need ratification from a sceptical Congress.