Recently, some media sources are reporting on the approach of Mauna Loa CO2 approaching or passing 410 ppm in 2017.
For example, Digital Journal reported on March 10, "In the next few
weeks, carbon dioxide is expected to pass the 410 ppm mark on a daily basis at
the Mauna Loa Observatory, something we have never experienced."
While it is true that MLO has not passed 410 ppm in the past, it is helpful to note that this benchmark has already been exceeded elsewhere.
The reality is that 30 monitoring stations exceeded daily readings of 410 ppm by June, 2016. The locations marked with yellow stars below are those who passed that point by that month.
Source: NOAA ESRL Active Data Viewer and Station Data https://www.esrl.noaa.gov/gmd/dv/iadv/
What is more concerning is how many stations have reported preliminary readings above 415 and in one case almost 420 ppm.
For example, Barrow, Alaska has two preliminary readings above 420 ppm, that if not determined to be from a local source, will be a significant jump in CO2 concentration at that location.
Cold Bay, Alaska had numerous readings above 410 ppm through 2016. and may approach 415 ppm this year.
Ny-Alesund Svalbard has readings above 415 ppm in early 2017, which is not the peak of its CO2 cycle.
Further south, Iceland has already recorded preliminary CO2 above 410 ppm in 2017.
Finally, Tiksi, Russia has preliminary readings just shy of 420 ppm, and those will likely go higher later this spring if previous years represent a pattern for its increase in the next few months.
While Mauna Loa is important as the longest running CO2 concentration reporting site, it is not the first to pass 410 ppm. That was done last year in numerous locations. It is just catching up.