After the disappointment of Copenhagen in 2009, hopes are high that global leaders will strike a comprehensive deal to combat climate change at the COP21 meeting in Paris.
Still, it will be challenging for more than 190 countries to agree on how exactly they'll keep the globe from overheating.
"There are still a number of reasons to be optimistic," Mikael Karlsson, president of the activist network the European Environmental Bureau EEB, told CNBC.
This time around, private companies are on board, he said, while climate scientists and economists are much more clear on the devastating costs of failing to cut carbon emissions.
Here, we explore what could realistically be achieved before everyone goes home on December 11.