LONDON—Humanity has now entered a new climate reality era, with carbon dioxide concentrations expected to remain above the level of 400 parts per million throughout 2016 and for many generations to come, the World Meteorological Organization says.
The WMO, the United Nations system’s leading agency on weather, climate and water, says the globally averaged concentration of carbon dioxide in the atmosphere reached “the symbolic and significant milestone of 400 parts per million” for the first time in 2015 and surged again to new records in 2016 on the back of the very powerful El Niño event.
CO2 levels reached the 400 ppm barrier for certain months during 2015 and in certain places, but they have never done so on a global average basis for the entire year. The WMO says in its annual Greenhouse Gas Bulletin that the growth spurt in CO2 was fuelled by El Niño, which started in 2015 and had a strong impact well into this year.