In a paper published today in Nature Climate Change, Lead author Professor Richard Betts, of the Met Office Hadley Centre and the University of Exeter, say that 2016 will be the first year with concentrations of carbon dioxide above 400 ppm (parts per million) all year round.
Betts explains that atmospheric carbon dioxide concentrations are rising year-on-year due to human emissions, but while El Nino was in the picture, sea-surface temperatures in the southern Pacific Ocean helped to warm and dry tropical ecosystems, reducing their uptake of carbon. This is one reason why forest fires were so much worse than usual, according to the Met office.
Added to the impact of El Nino on atmospheric CO2 concentrations, human emissions are 25 percent higher than they were during the last big El Nino in El Niño in 1997-1998. Charles David Keeling began recording CO2 at Mauna Loa, Hawaii, in 1958. It was he who noticed the rising trend in CO2 levels over a period of time. Early measurements made by Keeling showed concentrations of CO2 were around 315 ppm.
Now, 60 years later, atmospheric carbon dioxide levels have been rising at an average rate of 2.1 parts per million, but using a seasonal climate forecast model and the statistical relationship with sea temperatures, Betts and his colleagues are forecasting that the rise this year could be a record 3.15 + – 0.53 ppm.
Betts and his team are saying the average atmospheric CO2 concentration in 2016 will be 404.45 +-0.53 ppm, dropping to 401.48 +- 0.53ppm in September of 2016 before continuing to climb the next year. CO2 concentrations are also seasonal. Generally, this means that in the summer months, plants draw down CO2, releasing it again in the fall and winter, reports Phys.org.
Professor Betts said: “Carbon dioxide at Mauna Loa is currently above 400 parts per million, but would have been expected to drop back down below this level in September. However, we predict that this will not happen now because the recent El Niño has warmed and dried tropical ecosystems and driven forest fires, adding to the CO2 rise”.
In early May of this year, scientists warned us that once global CO2 levels reach above 400 ppm, there was the very good chance they would never drop below that point, even if we do manage to curb greenhouse gas emissions, according to the story in Digital Journal.
In April this year, the monthly CO2 average was 407.57 ppm at Mauna Loa. In April 2015, the CO2 level was 403.94ppm. In May this year, the CO2 level had risen to 407.70ppm, while in May 2015, it was 403.94ppm. Yesterday, June 12, 2016, the CO2 level for the day was 407.26ppm. One year ago on the same day, the level was at 402.46ppm. So you can see how much the levels have risen in just one year.
Chris Jones, also of the Met Office Hadley Centre and another co-author, said: “Studying how these natural cycles interact with human influences is an important part of climate science. Making and testing predictions like this helps us build our understanding and further develop climate models.”
