Enter your email address:

Enter the recipients' email addresses, separated by commas:

Message:

Could Obama actually return from Copenhagen with a deal? The White House is suddenly feeling a gust of optimism. Richard Wolffe on how he might earn that Nobel prize after all. Plus, read our user's guide to the state of the climate change debate.

The last time President Obama made a late schedule change to travel to Copenhagen, the gamble failed badly: despite a spirited speech, he returned empty-handed as his hometown of Chicago lost the contest to host the 2016 Olympics.

But late Friday afternoon, the White House repeated the gamble. Less than two months since their last Copenhagen debacle, the...