Keeling Curve Website Wants You To Know When CO2 Levels Hit 400 Parts Per Million

On Monday, Hawaii’s Mauna Loa Observatory measured CO2 levels in the air of 398.36 parts per million (ppm). And that means carbon dioxide, the main gas driving climate change, will soon hit 400 ppm for the first time in human existence

The world’s longest unbroken record of atmospheric CO2 levels is the “Keeling Curve” measured at Mauna Loa since 1958. The curve was initiated by Charles David Keeling and is maintained by his son, Ralph F. Keeling, at the Scripps Institution of Oceanography (where I did my Ph.D. research on the physical oceanography of the Greenland Sea).

The Scripps folks want you to know precisely when we hit 400 ppm so they have set up a website and even a twitter feed, @Keeling_curve, that will tweet out the CO2 level every day.

The 400 ppm level is another major milestone on humanity’s accelerating path to destroying a livable climate. As climatologist Chris Field told the AP, “It’s an important threshold. It is an indication that we’re in a different world.”

How different can be seen in this chart:

The 400 ppm level was passed in parts of the Arctic last May because, as E&E News (subs. req’d) notes, “It typically gets to a peak concentration above that of the rest of the world due to winds blowing CO2 up north in the spring.”

A 2009 article in Science reported that when CO2 concentrations were sustained at this level 15 million years ago, it was 5° to 10°F warmer and seas were 75 to 120 feet higher.

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32 Responses to Keeling Curve Website Wants You To Know When CO2 Levels Hit 400 Parts Per Million

  1. David Goldstein says:

    Ha!, Joe- I just posted this comment on another CP story- I’ll repost it here: CO2 nerd here with the weekly Mauna Loa update: as of 4/14/2013 398.41 ppm a 2.4 ppm increase over last year. 1.59 to go for a weekly 400 reading…can we make it???? I am going to go out on a limb here and predict the highest weekly reading sometime this May as 399.89! (what can I say, I am a Philadelphia sports fan and I am used to falling short. That would mean almost a year wait for 400). Though reaching 400 next month may give my solar stocks a boost!

  2. prokaryotes says:

    People might argue:”Oh it’s just 400 ppm, so little…”

    Yet, small amounts can have a huge impact, for instance with carcinogen benzene…

    Production of Benzene from Ascorbic Acid and Sodium Benzoate

    Recently, a great deal of attention has focused on the presence of benzene in certain bottled and canned soft drinks and fruit drinks

  3. prokaryotes says:

    Most visitor’s of CP probably know this lecture yet, but for those who don’t i can highly recommend it

    Richard Alley: “The Biggest Control Knob: Carbon Dioxide in Earth’s Climate History”

  4. Paul Magnus says:

    This is exciting…

  5. M Tucker says:

    I think if you remember that it happened about 2013 or 2014 that will be good enough. There isn’t a whole lot of difference between what you get at 400 compared with 398. Just remember that we hit 350 around 1990 and about 24 years later we got to 400. Also remember that the rate of increase has been increasing. A few years back it was 2 ppm/year and now it is about 2.5ppm/year. Remember we live in a time of accelerating CO2 concentration. Remember the lack of resolve to address this civilization threatening issue. Those born today will live through the doubling.

  6. Superman1 says:


    I commented on your HP article a while back. One point I wanted to add.

  7. Superman1 says:

    You were motivated to do whatever had to be done to solve your problem, you did it, and it worked. The seven billion residents of this planet have little, if any, motivation to solve the climate change problem, they are not willing to make the sacrifices required as you were, they are doing essentially nothing on the scale of what is required, and the global climate models predict 5-6 C (end of species) by the end of the century on the present path.

  8. Superman1 says:

    Given that these global climate models exclude the positive feedbacks that we see today and that are starting to accelerate, those temperatures will in fact be reached well before the end of the century if we continue along the present path. All credible predictions I have seen continue along the present path.

  9. Superman1 says:

    Further, the reactions of the American, Canadian, Australian et al governments to exploit their ‘recent’ fossil fuel resource discoveries as fully and rapidly as possible give validation to the business as usual predictions.

  10. David Goldstein says:

    Yes- this is obviously a fundamental and enormous difference between my situation and the climate situation – and I have to tell you, I went through A LOT of denial (multiple emergency room visits and hospitalizations, etc.) before I learned to take proactive and responsible action. I learned, finally, that it was much better to avoid suffering if possible. An obvious lesson but one that took me a lot of unnecessary suffering to internalize.

  11. David Goldstein says:

    BTW, Supe- here is my latest HuffPost article. It is a bittersweet climate change fable:

  12. Merrelyn Emery says:

    If you mean a doubling to 700 or 800ppm, I doubt it. Things (ecology and economy) are falling apart far too fast for that, ME

  13. David Goldstein says:

    I am guessing that he meant doubling in the sense of 560 (double the pre fossil fuel 280)? That would be in about another 50 or so years assuming a 3 ppm annual emissions.

  14. Rabid Doomsayer says:

    Look at graph and be scared. We are as far above the maximum natural CO2, as the maximum is above the minimum. There is a bigger difference in what we have done than there is, between the depth of an ice age and the heighth of an interglacial.

    What we have done in a century and a bit, took nature thousands of years. There will be consequences, consequences beyond your imagination.

  15. prokaryotes says:

    And after each larger Co2 excursion it took millions of years to bury the Co2 again.

    USA TODAY ‎- 3 hours ago
    Carbon dioxide now at highest level in 5 million years

    For the first time in roughly 5 million years, the amount of carbon dioxide in the Earth’s atmosphere could top 400 parts per million in the Northern Hemisphere next month.

    Human ancestors were just learning how to walk on two feet about that time, in a world that was much warmer than the one we walk on today.

    Carbon dioxide is the greenhouse gas that is responsible for 63% of the warming attributable to all greenhouse gases, according to the National Oceanic and Atmospheric Administration’s Earth System Research Lab.

    This latest report comes from the Scripps Institution of Oceanography, keepers of the famed “Keeling Curve,” the longest continuous record of carbon dioxide measurements on the planet. The measurements were begun in 1958 by Scripps climate scientist Charles Keeling and taken near the top of Mauna Loa on the Big Island of Hawaii.

    When Keeling first began his measurements, the amount of carbon dioxide (also known as CO2) was 316 parts per million (ppm). As of Tuesday, the reading was 398.44 ppm as measured at Mauna Loa.

    While CO2 levels topped 400 at stations at high northern latitudes last May, the Mauna Loa record has never exceeded 400 in the monthly average, according to Ralph Keeling of Scripps. The monthly average could top 400 ppm in May, he says. Daily and weekly averages of 400 ppm are also possible in May for the first time. Ralph Keeling is the son of the late Charles Keeling.

    For the past 800,000 years, CO2 levels never exceeded 300 parts per million, according to Scripps, which measures CO2 levels along with several other agencies, including NOAA. Records of past levels of CO2 are found in samples of old air preserved as bubbles in the Antarctic ice sheet, Scripps reports.

    “The 400-ppm threshold is a sobering milestone, and should serve as a wake up call for all of us to support clean energy technology and reduce emissions of greenhouse gases, before it’s too late for our children and grandchildren,” said Tim Lueker, a Scripps oceanographer.

    The daily level of carbon dioxide can be followed on Twitter @keeling_curve

  16. Lee Norton says:

    CO2 of 400 ppm is just another number. We’ve been in deep trouble since 1987 when we passed 350 ppm, and even that may be too high. Check out Dan Lunt’s (U. of Oxford) mid Pliocene numbers of 390 ppm, 2.9 degrees warmer than our pre-industrial value and sea levels 15-20 m higher than today. There were no man-made greenhouse gasses back then and CH4 had not doubled. It’s just taking awhile for our climate to stabilize to our atmospheric values. We’ll be warming for a long time even if we halt all carbon emissions now. Getting back to 350 ppm or less is quite wishful if you run the numbers.

  17. Merrelyn Emery says:

    Those 50 years are likely to contain cataclysms of verious types. All of them will have the effect of closing down some human activities. The cumulative effect will be a multiplier because our current systems are extremely fragile, ME

  18. Paul Klinkman says:

    Well I’m from New England, a place with an embarrassment of sports riches.

    According to their website, individual readings at the Mauna Loa Observatory have exceeded 400 ppm recently. However, the daily average has stayed under 400. So, is it the daily average or the weekly average over 400 that counts for people? Or, is the general hockey stick trend frightening you?

  19. Paul Klinkman says:

    “And after each larger Co2 excursion it took millions of years to bury the Co2 again.”

    You may be right, but we should want to know whether you’re right or wrong. How quickly does “nature” sequester carbon? Any actual forecasts or wild guesses out there? Where’s the evidence? Which ecosystems (peat bogs, for example) have the most success at carbon sequestration over a 10,000 year period? Can we create more bogs?

    To the point, our world will want to sequester maybe half of the atmosphere’s carbon. Speeding up the natural process might be possible and affordable.

  20. BobbyL says:

    Hitting 450 will be much more dramatic than hitting 400 since that is supposed to be the threshold for dangerous (catastrophic ?) climate change. I predict we will hit 450 around 2030, a few years after India overtakes China as world’s biggest coal user, and millions of gallons of bitumen from the Alberta tar sands are flowing through the Keystone, Northern Gateway and other pipelines, and the US is just one more nation fracking like mad for natural gas,and oil drilling in the Arctic is going full blast.

  21. prokaryotes says:

    This graphic here shows that it took the sink millions of years to get from an ice free state (with high Co2) to todays balanced state with ice at the poles.

    The sink and source of CO2 (sink = weathering of rocks and source = volcanoes) depends on continental drift.

  22. prokaryotes says:

    And yes we can sequester carbon today, with biochar technology.

    The Intergovernmental Panel on Climate Change (IPCC) reported Biochar as a key technology for reaching low carbon dioxide atmospheric concentration targets. The negative emissions that can be produced by Bio-energy with carbon capture and storage (BECCS) has been estimated by the Royal Society to be equivalent to a 50 to 150 ppm decrease in global atmospheric carbon dioxide concentrations. Annual net emissions of carbon dioxide (CO2), methane and nitrous oxide could be reduced by a maximum of 1.8 Pg CO2-C equivalent (CO2-Ce) per year (12% of current anthropogenic CO2-Ce emissions; 1 Pg=1 Gt), and total net emissions over the course of a century by 130 Pg CO2-Ce, without endangering food security, habitat or soil conservation. Wikipedia

  23. prokaryotes says:

    And 1 negative feedback to climate change is more geomorphological response. From crust rebound and from increased weathering.

  24. Mulga Mumblebrain says:

    Not ‘likely’ ME, but certain. Add in ocean acidification, numerous other ecological disasters, economic implosion and global war over dwindling resources and shifts in economic power, and we have no hope, whatsoever, of making another 50 years, unless there is revolutionary change to all aspects of the global system as it is currently configured.

  25. Gingerbaker says:

    ““The last time carbon dioxide levels were apparently as high as they are today “” and were sustained at those levels “” global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland,” said the paper’s lead author, Aradhna Tripati, a UCLA assistant professor in the department of Earth and space sciences and the department of atmospheric and oceanic sciences.”

    So why is everyone touting a small review article in Science, which says that if we were to stop all CO2 emissions tomorrow, the global temperature would not go up?

    Should we not be expecting a time lag to equilibrium temperature much higher than today’s?

  26. BobbyL says:

    I think the lag time applies if we leveled off at 398 ppm. Then it would take three or four decades to reach the highest temperature that would be reached. To do that CO2 emissions would continue but be reduced from today’s levels. But CO2 emissions are not going to stop tomorrow. So the global temperature will keep going up.

  27. Greg says:

    Yes, very true. A close friend who is a chemist ended his horrible migraines by cutting out the sodas he suspected had sodium benzoate. Key was that the manufacturer had insisted they had removed the ingredient and he had trusted them but they hadn’t. Trust but verify…

  28. Brent Roberts says:

    I am curious about something. I have heard that lag time takes 30 or 40 years, but I have also heard it takes centuries to reach equilibrium after CO2 emissions stop. Are we talking about two different things here? What’s the difference?

  29. Dennis von Itter says:

    Congradulations you Humans! You’ve changed the World. What are you going to do next, go to Disneyland?

  30. wili says:

    Aren’t we already past that in CO2 equivalence?

  31. wili says:

    Well, from what I understand, there are two types of lags that kind of work in opposite directions.

    The first is the lag that Gingerbacker rightly referred to–the lag in heating that CO2 will cause.

    I think of this as very quickly building a tall dam across a small stream: It takes a while for the water-level to build up to the level of the dam. So with heat building up behind the CO2 “dam.” (I almost wrote “damn”; perhaps that would have been more appropriate, since we seem intent on damning ourselves and our progeny to a hellish future.)

    The other lag, working in the other direction (but leading to ocean acidification) is the ocean’s uptake of CO2.

    I don’t know how long it takes for the level of CO2 dissolved in the ocean to be in equilibrium with the CO2, but apparently it is not an instantaneous process.

    What we really have to keep our eyes on (besides, of course, the needed immediate, near total draw-down of all fossil ‘death’ fuel use) is the multiple feedbacks that kick in at various points, and that are already kicking in, especially in the Arctic.

  32. shochin says: