A friend alerted me to this news item yesterday from the Met Office that had escaped my attention: El Niño drives record rise in atmospheric carbon dioxide. So because I haven’t downloaded the latest monthly Co₂ values from Mauna Loa for a while, I thought I would take a look. After a bit of refactoring of the application I did notice a surge in the rate of increase in Co₂ during recent months, in fact the April 2016 12 month rate of change was the highest since records started in March 1958, and was +4.16 ppm higher than the concentration of April 2015.
There must be a causal link between Co₂ and El Niño events, because you can see some of the recent events (1973, 1977, 1987, 1995, 1998 & 2003), standing out quite well in the rate of change chart. Don’t ask me how that comes about I just draw the graphs , but the Met Office article gives you more information.
Interestingly the Met Office article states that the average rate of increase is 2.1 ppm. I can only think that they mean an annual rate but they don’t say over what time period in the article. If it was at an average rate of 2.1 ppm and it has been going on since 1958 then surely the concentration levels would be at 315+(58 x 2.1) or 436.8 ppm in 2016 and far too high. In my graph above I have the decadal rise in Co₂ concentration at 15.2 ppm since 1958, which is annual rate of 1.52 ppm and much lower than the Met Office value. I think I have my maths in my application correct 315+(58 x 1.52) would give a 2016 figure of around 402.58 ppm.
It’s probably over the last 10 years, because if you limit your data like I’ve done in the following graph, you will see that the average rate of increase is higher at +21.9 ppm/decade over that period, or +2.19 ppm annually. I was never particularly brilliant at maths, but I did have a very good maths teacher Mr Brightmoor. One thing I did remember from his lesson was to include the units when I gave the answer, and hopefully I still try to follow what he said on all the graphs and tables I produce.
I did receive a nice reply from Richard Betts who wrote the original article, and he confirmed that the +2.1 ppm rate was over the last 10 years as I suspected, and not the entire 58 years of the series.