Bloomberg: The amount of carbon dioxide in the atmosphere surpassed a threshold not seen for 3 million years, exceeding 400 parts per million for the first time since researchers began tracking the data.
The main greenhouse gas blamed for global warming averaged 400.03 parts per million at the U.S. National Oceanic and Atmospheric Administrations Mauna Loa monitoring station in Hawaii on May 9, the agency said yesterday.
The level is considered a landmark by scientists and environmentalists, who say...