Six years after a fiasco in Copenhagen and a year before he leaves office, a Paris summit offers Barack Obama the chance to make his mark in the fight against climate change.
In December 2009, Obama left the Danish capital after signing on to a hastily issued statement by leaders hoping to save face.
His hair now greying, Obama will arrive tomorrow in the French capital 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.
After the terror attacks in Paris, Obama was among the first to say he would stick to his plans to attend climate talks tomorrow.
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 Obama has called the “disorganised mess” of Copenhagen.
This time, the ground has been well prepared in advance.
A year ago, Obama inked a deal with 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, Obama’s first meeting when he lands in Paris tomorrow will be with Chinese President Xi Jinping.
The negotiations in Paris will also be different, each country is setting its own targets rather than having binding targets imposed upon them.
That also means the agreement will not be a formal treaty, which would need ratification from a sceptical US Congress.
Memories are still fresh of the US legislative branch torpedoing the Kyoto climate deal.
Many analysts see Paris as a legacy moment for President Obama, “a capstone for all he has done domestically to move the US into a more sensible and inspiring place on climate change”.
“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,” according to Jennifer Morgan of the World Resources Institute.
Still, it is highly unlikely the Paris targets collectively limit global warming to two degrees centigrade 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,” Obama said in a recent interview.
“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.”