For the first time since record-keeping began, the average atmospheric concentration of carbon dioxide (CO2) hovered over the 400 ppm (parts per million) threshold for a full month, during March 2015, according to the National Oceanic and Atmospheric Administration (NOAA).
To be specific here, the average for the month was 400.83 ppm. Considering that this average has been growing rapidly over the last few decades, it was only ever a matter of time before this new record was achieved -- to give a better idea here, the average concentration of CO2 in the atmosphere rose by 0.75 ppm per year in 1959 and around 2.25 ppm per year in 2015.
“It was only a matter of time that we would average 400 parts per million globally,” stated Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network. “Reaching 400 parts per million as a global average is a significant milestone.”
“This marks the fact that humans burning fossil fuels have caused global carbon dioxide concentrations to rise more than 120 parts per million since pre-industrial times. Half of that rise has occurred since 1980.”
Considering that industrial activity is (as of yet) not really slowing down to any notable degree (the economic downturn has has some effect, even if only a minimal one), these concentrations are currently set to continue coming for quite some time into the future -- potentially bringing with them world-changing climatological, agricultural, and social, turmoil, and difficulties.
For those wondering, the 400 ppm threshold was indeed passed last summer, but with recurring fluctuations factored in, the global monthly average was still under 400 ppm -- despite the occasional breaking of the threshold at various times and in various regions.
To explain further, the global monthly average is calculated from the data obtained via 40 different, isolated sites around the world -- all of which are located far from sources of pollution that would/could skew the results.
As far as what this all means:
“Reaching 400 ppm doesn’t mean much in itself, but the steady increase in atmospheric greenhouse gases should serve as a stark reminder of the task facing politicians as they sit down in Paris later this year,” noted Ed Hawkins, a climate scientist at the University of Reading.
In other words, it's just a number -- but it's not just a number, it's a number on a sign on the side of the tracks as a train goes speeding by, right towards a brickwall.
Image by CO2Now