CO2 in the Earth’s atmosphere surged to a record high in 2016, according to the World Meteorological Organization (WMO). Last year’s increase was 50% higher than the average of the past 10 years. Researchers say a combination of human activities and the El Niño weather phenomenon drove CO2 to a level not seen in 800,000 years.
Scientists say this risks making global temperature targets largely unattainable. This year’s greenhouse gas bulletin produced by the WMO is based on measurements taken in 51 countries. Research stations dotted around the globe measure concentrations of warming gases including carbon dioxide, methane and nitrous oxide.
The figures published by the WMO are what’s left in the atmosphere after significant amounts are absorbed by the Earth’s "sinks", which include the oceans and the biosphere.
2016 saw average concentrations of CO2 hit 403.3 parts per million, up from 400ppm in 2015.
"It is the largest increase we have ever seen in the 30 years we have had this network," Dr Oksana Tarasova, chief of WMO’s global atmosphere watch programme, told BBC News.
"The largest increase was in the previous El Niño, in 1997-1998, and it was 2.7ppm; and now it is 3.3ppm. It is also 50% higher than the average of the last 10 years."