CO2 at 403.3 ppm

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.”

Another concern in the report is the continuing, mysterious rise of methane levels in the atmosphere, which were also larger than the average over the past 10 years. Prof Nisbet says there is a fear of a vicious cycle, where methane drives up temperatures which in turn releases more methane from natural sources.

Earlier in 2017, there was a publication that climate models needed to be corrected to correctly model the water loss in leaves in plants.

Prior to the adjustment the old models had projected temperature based upon CO2 ppm as follows.