The initial ’soft" deadline has come and gone, and the United Nations reports that 55 countries have signed on to the Copenhagen climate accord. Not much in the way of surprises, and well short of 193 countries that are party to the climate convention, but those 55 countries account for 78 percent of global greenhouse gas emissions.

As the L.A. Times reported, major environmental groups in the United States offered up a cautiously optimistic assessment. The accord might not be a treaty. It might not even be a global agreement, as it was never endorsed by all nations in Copenhagen. Worst of all, perhaps, the emissions commitments currently on the table leave something to be desired.

But it’s a start. For the first time, emerging economies have formally registered verifiable climate commitments, and bringing down emissions among developing nations will be critical given that they wil be responsible for virtually all of the emissions growth going forward. In exchange, developed countries have agreed to help with financing.

Whether the deal will hold, let alone gather momentum and become the foundation of a treaty, remains to be seen. The accord will face its next formal hurdle when the United Nations holds its annual climate convention in Mexico later this year.