Monthly Atmospheric CO2 Now Exceeds 400 ppm

Reprinted from our sister publication, CleanTechnica.

Chilean meteorologist takes air samples on Easter Island (NOAA)
Chilean meteorologist takes air samples for NOAA index on Easter Island (NOAA)

For the first time since people started tracking carbon dioxide in the earth’s atmosphere, the global average concentration of CO2 has surpassed 400 parts per million for an entire month.

Says Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network, about the record carbon dioxide level:

Air sampling by boat in the Pacific (NOAA)
Air sampling by boat in the Pacific (NOAA)

“It was only a matter of time that we would average 400 parts per million globally. We first reported 400 ppm when all of our Arctic sites reached that value in the spring of 2012. In 2013 the record at NOAA’s Mauna Loa Observatory first crossed the 400 ppm threshold. 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.”

NOAA bases its global carbon dioxide numbers on air samples taken from 40 sites around the world. The samples then ship for analysis to NOAA’s Earth System Research Laboratory in Boulder, Colorado. The lab issues monthly concentration numbers after processing these global results.

Ed Dlugokencky, the scientist who manages the global network, says that NOAA selects particular sites “because the atmosphere itself serves to average out gas concentrations that are being affected by human and natural forces. At these remote sites we get a better global average.”

Recent global mean CO2 concentration, March 2015 (NOAA)The NOAA March report also prompted this prediction from Dlugokencky:

“The global average will remain above 400 ppm through May, the time of year when global carbon dioxide concentrations peak due to natural cycles on top of the persistent rising greenhouse gases. Decaying plant matter and soil organisms give off carbon dioxide gas all year long, but the dormant period in plant growth allows the respiration of carbon dioxide to dominate during those months. Carbon dioxide levels drop back down as plants begin to bloom, using carbon dioxide for photosynthesis in late spring and summer.”

NOAA’s latest results confirm that atmospheric CO2 is increasing 100 times faster in the age of humans than it has in natural rises in the past. James Butler, director of NOAA’s Global Monitoring Division, adds that it would be difficult to reverse the increases of greenhouse gases which are driving increased atmospheric temperatures. “Elimination of about 80% of fossil fuel emissions would essentially stop the rise in carbon dioxide in the atmosphere, but concentrations of carbon dioxide would not start decreasing until even further reductions are made, and then it would only do so slowly.”

In an interesting sidelight, the International Energy Agency reported a few weeks ago that global emissions from fossil fuel energy use had stayed at the same levels last year as in 2013. However, despite the cackling of climate change deniers at this finding, annual variations are virtually meaningless against the total climate picture. Note that NOAA data show that carbon dioxide concentrations actually grew from 2012 to 2014 by 2.25 ppm per year, the greatest amount ever recorded over three consecutive years.

54 thoughts on “Monthly Atmospheric CO2 Now Exceeds 400 ppm”


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  2. Curious as to why the northern hemispheres’ spring / summer causes the level to drop and the southern hemispheres’ spring / summer have no affect. Shouldn’t there be two cycles per year?

    1. Most of the land mass on earth is in the northern hemisphere. Thus, there is a lot more plant growth in the northern hemisphere during the northern summer season than there is in the southern hemisphere during the southern summer season.

  3. This is excellent news. If CO2 levels continue to increase at a rate of 2.25 ppm per year, then in 355 years CO2 levels will finally reach their minimum optimum level for flora at 1,200 ppm. We can do better and increase CO2 levels at a faster rate if it was not for the anti-science, anti-human, leftist fanatics who want the impossible – a static climate.

    1. Fossil fuel reserves will likely be depleted in much less than 355 years, so I am not sure what can be done to keep it increasing.

      I doubt CO2 concentration will ever reach even the estimated 1950 ppm that was common 150 million years ago during the Jurassic Period.

      1. Alaska alone has enough hydrocarbons to last 400+ years. Atmospheric CO2 levels of 1,950 ppm is a bit higher than some plants would like. Recent studies have shown wheat exposed to 1,800 ppm CO2 has a deteriorating effect. The range they found that most flora responded best was between 1,200 ppm and 1,500 ppm.

        Currently atmospheric CO2 accounts for 2.72% (1.88 W/m^2) of all radiative forcing. A three-fold increase in CO2 levels would not be a significant increase.

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