The Copenhagen climate summit heats up this week with U.S. President Barack Obama speaking at the U.N. conference on Friday, and the arrival today of Secretary-General Ban Ki-moon, who called upon participating nations to step up the climate talks and “seal the deal” for the good of all mankind. More from the U.N. press center:

“The two-week summit under way in the Danish capital is ‘as momentous as the negotiations that created our great United Nations… from the ashes of war more than 60 years ago,’ Mr. Ban said at the opening of the conference’s high-level segment.

‘Once again, we are on the cusp of history.’

With the two-week summit set to wrap up on Friday, Mr. Ban underscored that nations cannot be allowed to fail in the home stretch, urging countries to put aside their ‘maximalist’ negotiating positions and ‘unreasonable’ demands.

…Talks were briefly suspended yesterday by African nations over the future of the Kyoto Protocol, currently the only legally binding pact on climate change.

Many industrialized countries are hoping to merge the Protocol and the outcome of the two-week Copenhagen meeting, in its second week, into a single agreement.

However, their developing counterparts, among the least responsible for greenhouse gas emissions, want to extend the Protocol past 2012, when its first commitment period ends, and hammer out a separate agreement this week in the Danish capital.”

(Photo by Neilson Barnard/Getty Images)