Carbon dioxide at highest level ever directly measured

By Tom Yulsman | June 8, 2018 2:42 pm

Rather than declining, CO2 levels in the atmosphere are rising thanks to continuing growth in emissions of the climate-altering gas

Carbon dioxide released into the atmosphere by human activities moves and changes through the seasons. This visualization shows the behavior of carbon in the atmosphere from Sept. 1, 2014, to Aug. 31, 2015, based on observations and modeling. (Source: NASA Goddard Space Flight Center/K. Mersmann, M. Radcliff, producers)

This visualization shows the behavior of carbon dioxide in the atmosphere from Sept. 1, 2014, to Aug. 31, 2015, based on observations and modeling. In May, atmospheric CO2 reached the highest levels ever directly measured. (Source: NASA Goddard Space Flight Center/K. Mersmann, M. Radcliff, producers)

The Paris Agreement was intended to turn the world onto a new path, one that would limit the risks and impacts from climate change through lowered emissions of carbon dioxide and other greenhouse gases.

But according to the latest indication, we’re still on the old path.

Carbon dioxide


In May, CO2 levels in the atmosphere exceeded 411 parts per million, as measured at an observatory atop Hawaii’s Mauna Loa, according to an analysis released yesterday by scientists with the National Oceanic and Atmospheric Administration and the Scripps Institution of Oceanography.

That’s significant because it’s the highest monthly average ever directly measured. It also suggests that 2018 could turn out to be the seventh year in a row with large increases in concentrations of the heat-trapping gas.

To put the current CO2 level in perspective, consider that right before the preindustrial revolution — before we ramped up our burning of fossil fuels — the concentration stood at just 280 parts per million.

Even more telling: Research shows that you have to go back at least 3 million years to find a time when CO2 concentrations in the atmosphere were this high. And the impact we’ve already had on the atmosphere will linger for a very long time to come. As Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network, put it in a release from NOAA:

“CO2 levels are continuing to grow at an all-time record rate because burning of coal, oil, and natural gas have also been at record high levels. Today’s emissions will still be trapping heat in the atmosphere thousands of years from now.”

The growth rate of CO2 in the atmosphere averaged about 1.6 parts per million per year in the 1980s, and 1.5 ppm per year in the 1990s. But then the growth rate jumped to 2.2 ppm per year during the last full decade. And there’s no sign that the current decade will break the trend.

Annual mean carbon dioxide growth rates for Mauna Loa.

The annual mean growth rates for carbon dioxide in the atmosphere as measured atop Mauna Loa in Hawaii. In the graph, the horizontal lines indicate decadal averages of the growth rate, for 1960 through 1969, 1970 through 1979, and so on. (Source: NOAA/ESRL)

“Many of us had hoped to see the rise of CO2 slowing by now, but sadly that isn’t the case,” said Ralph Keeling, director of the Scripps CO2 Program, quoted in a release. “It could still happen in the next decade or so if renewables replace enough fossil fuels.”

Under the Paris Agreement, 178 nations have committed to reducing their emissions of carbon dioxide and other greenhouse gases. The goal: Limit global warming to no more than 2 degrees Celsius over pre-industrial levels.

Unless we can get onto another emissions path very soon, it’s likely that we’ll blow through that goal.


Radiative forcing, relative to 1750, due to carbon dioxide alone since 1979.

Radiative forcing, relative to 1750, due to carbon dioxide alone since 1979. The percent change from January 1, 1990 is shown on the right axis. (Source: NOAA/ESRL)

The graph above may look a little intimidating, but take a minute to consider what it shows: How CO2’s impact on global temperature has grown since the 1970s.

Scientists call this “radiative forcing” — a measure of CO2’s influence on the amount of energy, ultimately derived from the Sun, that is retained in the atmosphere, thereby causing warming. The direct warming influence on the climate by CO2 has risen by 50 percent since 1990.

Given CO2’s impact, it should come as no surprise that the planet’s average surface temperature has risen about 2 degrees Fahrenheit, or a little more than 1 degree Celsius, during the last century. Last year was the third consecutive year in which global temperatures were more than 1.8 degrees Fahrenheit (1 degree C) above late nineteenth-century levels.

And then there was this news from NOAA a couple of days ago:

The average May temperature across the contiguous U.S. was 65.4 degrees F, 5.2 degrees above average, making it the warmest May in the 124-year record, according to scientists at NOAA’s National Centers for Environmental Information.  This surpassed the previous record of 64.7°F set in 1934, during the dust bowl era. There were more than 8,590 daily warm station records broken, or tied, in May.

  • Mike Richardson

    Unfortunately, with the U.S. out of the Paris Agreement, the chances of slowing CO2 emissions anytime soon. And not surprisingly, temperatures are rising globally. Given the May we had in Louisiana, I can easily believe NOAA’s announcement about record temperatures last month. Apparently, it wasn’t just my own local anecdotal observation.

    • Tom Yulsman

      Actually, U.S. greenhouse gas emissions peaked in 2007. You have to go all the way back to 1992 to find a year with lower emissions. See Figure ES-1 here:

      • Mike Richardson

        Wind and solar power becoming more common, and increasingly efficient vehicles likely played a role in that, as well as the economic downturn after 2008. But we now have an EPA administrator who wants to weaken vehicle emission standards, and a President who wants to subsidize coal and oil while cutting incentives for alternative energy. This, combined with an economy that (for the moment, at least) continues to grow, makes me doubt we won’t see rising emissions in this country again. Regardless, we certainly aren’t taking a lead in trying to speed the reduction of greenhouse gas emissions.

        • 18wheel

          Wind and solar and electric vehicles will supplement not replace: hydrocarbon use will increase thirty more years, then flatten off thirty following simply as a result of supply and demand. The only thing that will change this is new discoveries. The surest way to make those is to keep the economy functioning and the kids educated instead of indoctrinated. The case for the English-speaking world is only fair, and we are burying more children in superstition and hysteria daily.

          • Mike Richardson

            What does speaking English have to do with carbon emissions?

  • 18wheel

    1) this is a rehash of figures and graphics put out a month or two ago 2) if you believe carbon dioxide rising from 0.03% to 0.04% over two centuries is the main driver, when you can’t explain the Medieval Warm and Little Ice Age in hindsight, I got a bridge to sell you… The scam is this: convince people of carbon sin, tell them every weather event is because climate change (or the gods are angry) and sell indulgences to the feeble-minded.

    • Tom Yulsman

      Your comments are a rehash of tired old talking points that have been debunked innumerable times. And I’ve found that actually providing the science to debunk them never convinces anyone. So I won’t bother. Moving forward, keep in mind that this is a science magazine, so please leave the politics (“scam,” “carbon sin,” “gods are angry,” “sell indulgences,” “feeble-minded”) for another site. On another note, thank you for eschewing ad hominem attacks. I’m hoping everyone will keep it that way.

  • TLongmire

    “Today’s emissions will still be trapping heat in the atmosphere thousands of years from now.” There is no way this is factual in any meaningful way. China is wise enough to realize that climate modification is the future and they will soon be turning their western deserts green and capture huge amounts of carbon in the process.

    • Tom Yulsman

      Pieter Tans is saying that CO2 that we’ve put into the environment already will remain in the Earth system for thousands of years — because that’s how long it will take for that CO2 to be geologically sequestered. As imply, the way to change that is not just to stop emitting CO2 but to draw it out of the atmosphere. Given the failure of the world so far to reduce emissions, I find it far-fetched that we’ll go further to actually draw down what we’ve already put into the environment. But I hope we will. Also, reforestation and the like can only take care of so much, not the entire problem.

      • TLongmire

        If I had billions of dollars and wanted to make a measurable difference I’d find a desert, irrigate it, plant it full of hybrid poplars, and create biochar on a 5/8 year cycle of burial/expansion process.

      • Andrew Worth

        “Today’s emissions will still be trapping heat in the atmosphere thousands of years from now.”
        60% of the CO2 pulse is removed through land and ocean uptake within 100 years, nearly 80% is removed within 1000 years.

      • Damn Nitpicker

        Reforestation might be the wrong thing to do. If you think the Earf is overheating, well, consider
        a farmer’s field … “re-foresting” that field would lower the surface albedo, probably causing more insolation to be retained, exacerbating the perceived problem.

        Baldocchi 2001: ”Changing a landscape from forest to agricultural crops, for instance, increases the surface’s albedo and decreases the Bowen ratio [the ratio between the flux densities of sensible and latent heat exchange; i.e., increasing the latent heat] (Betts et al. 1996); forests have a lower physiological capacity to assimilate carbon and a lower ability to transpire water, as compared to crops (Kelliher et al. 1995; Baldocchi and Meyers 1998).”

        Baldocchi, Dennis, et al. 2001 “FLUXNET: A new tool to study … carbon dioxide, water vapor, and energy flux densities. Bulletin of the American Meteorological Society

        Myhre & Myhre 2003: ”A distinct feature in all the calculations is the negative radiative forcing at the northern midlatitudes due to the conversion of forest to cropland.

        ”Betts (2000) … his study revealed that the planting of trees, to reduce the increase in atmospheric CO2, in order to mitigate global warming, may actually lead to the opposite, as the vegetation changes result in a heating …”

        ”Snow-covered areas have much higher surface albedo over open land (as cropland) than in forested areas. This effect causes a temperature decrease in the case of deforestation, particularly at high latitudes, …”

        Myhre, Gunnar, and Arne Myhre 2003. “Uncertainties in radiative forcing due to surface albedo changes caused by land-use changes.” Journal of Climate



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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