The United States has declared that greenhouse gases may be threatening to human health — as well as to planetary health.

The announcement by the Environmental Protection Agency has been welcome for many climate activists, and also for world leaders gathered at the UN Climate Summit in Copenhagen, Denmark. 192 countries including the US are represented in Copenhagen.

The Summit will continue until December 18, and hopefully will result in a strong world agreement to curb greenhouse gas emissions.  For more on the Climate Summit, you can check out BBC coverage:Copenhagen.

You can also read Tweets from Copenhagen by New York Times environmental reporter Andy Revkin here:Revkin Tweets.