The Scripps Institution of Oceanography measured an average of 388.92ppm CO2 concentration at their Mauna Loa, Hawai’i’s Observatory during October 2011 and 390.31ppm CO2 concentration during November 2011. These readings are from the Scripps’ dataset, not NOAA’s, which was my original data source when this series began.
That value is the highest value for October and November in recorded history. Last year’s 387.15 and 388.62 were the previous highest respective values ever recorded. This year’s readings are 1.77ppm and 1.69ppm higher than last year’s. While under 2ppm per year, these two increases are significant. Of course, more significant is the unending trend toward higher concentrations with time, no matter the month.
The yearly maximum monthly value normally occurs during May. This year was no different: the 394.34 concentration (value updated since my last post) is the highest value reported both this year and all time.
I am more convinced than earlier this year that we will not witness CO2 concentrations below 390ppm during any calendar month. September and October were the only months this year which recorded concentrations below 390ppm. Judging by the year-over-year increases seen per month in the past 10 years, I predict 2012 will not see a concentration below 390ppm. I had earlier predicted that 2011’s minimum would be ~388ppm. I overestimated the minimum somewhat since both September’s and October’s measured concentrations were just under 389ppm.
CO2Now has the following graph on their front page:
It shows concentrations in the Scripps dataset going back to 1958. As I wrote above, concentrations are persistently moving upward. For additional reference, here are two graphs showing historical CO2 emissions and historical CO2 concentrations dating back 10,000 years:
Courtesy of Skeptical Science
Courtesy of Skeptical Science
And while previous increases in CO2 concentrations occurred naturally (i.e., PETM), this event is decidedly unnatural. Moreover, it is occurring over an incredibly short time-frame. It is the speed at which concentrations are rising (see last figure above) that is likely to pressure ecosystems in the coming centuries.
400ppm will be a much-discussed threshold due to its psychological significance. We will likely pass that threshold on an annual basis in 2015. 450ppm is another threshold thrown about in the global warming discussion. We will likely pass that threshold in the late 2030s – or about 25 years from now. Given our historical emissions to date and the likelihood that they will continue to grow at an increasing rate in the next 25 years, we will pass a number of “safe” thresholds – for all intents and purposes permanently as far as concerns our species. It is time to start seriously investigating and discussing what kind of world will exist after CO2 concentrations peak at 850 and 1100ppm. I don’t believe the IPCC has done this to date. To remain relevant, I think it will have to do so moving forward.
Cross-posted at SquareState.