It’s official: There will be no binding agreement to address global warming negotiated at Copenhagen next month. World leaders dashed high hopes for a treaty this year, rolling back expectations after it became clear that a strong treaty would be too politically costly for the summit’s major players, including the United States. Commentators are somber, if unsurprised, by the world’s unwillingness to negotiate a strong successor to the Kyoto Protocol, which is due to expire in 2012. Much of the frustration and disappointment has come to rest on President Obama. Pundits argue that his inability to deal aggressively with global warming, as he promised during his campaign, is embarrassing within the United States and abroad. Here’s why: