delegates converged sunday for the grand finale of two years of tough, sometimes bitter negotiations on a climate change treaty, as u.n. officials calculated that pledges offered in the last few weeks to reduce greenhouse gases put the world within reach of keeping global warming under control.

yvo de boer, the u.n.'s top climate official, said on the eve of the 192-nation ugg classic crochet conference that despite unprecedented unity and concessions, industrial countries and emerging nations need to dig deeper.

"time is up," de boer said. "over the next two weeks governments have to deliver."

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