It's definitely good news that he is visiting Copenhagen though the timing is odd. If he decides to actively engage in the move for change, even better. The note of caution though is that on paper it does sound like a drive by meeting which suggests it's a low priority. Whether he is serious or not will be known quickly enough by all involved. Obama has backed out of too many battles in the US so if this happens in Europe, he may start losing even more friends out there. At the moment, most Europeans still see him as the candidate of a year ago as opposed to the cautious politician we now know in the US.
Attending the talks but not committing to the more important sessions with world leaders doesn't scream of confidence or support. What makes this a particular problem is that the US is at the top of the pile for being part of the environmental problems faced by the world. The US consumes much more energy per household than Europe yet the meetings are somehow not important to the White House.
Obama will travel to Copenhagen on 10 December, on his way to collect the Nobel peace prize in Oslo the next day. But the White House gave no indication that the president was prepared to return to the city when Gordon Brown and 60 or more world leaders fly in to add impetus to the final deal one week later on 18 December - the last day of the talks.
The Observer revealed this week that the US administration was poised to announce a specific figure for cuts ahead of the Copenhagen talks.
Obama's commitment to attend the talks was welcomed by the UN and many environment groups but dismissed by others as a photo opportunity designed to upstage the other 60 world leaders.
