World CO2 Averages Touch 402.2 PPM Daily Values in Early April, 102 PPM Higher Than at Any Time in Last 800,000 Years

There’s a tale in the ice. A record of past atmospheres locked away as snowfall trapped air bubbles and then compressed them into thin layers age after age over tens of thousands of years. Over the last few decades, scientists have been drilling holes in the great ice packs of Greenland and Antarctica. Their quest? To unlock this tale and reveal a direct record of global greenhouse gas levels through the deep past.

What their drilling uncovered was both quite informative and rather chilling. First, it showed that, for more than 800,000 years, global CO2 levels had been relatively stable in a range of 180 to 300 parts per million. As the levels of heat trapping CO2 rose, temperatures peaked during brief interglacials. And as levels fell, temperatures plunged back into ice age conditions.

Global temperature flux during these swings from ice age to interglacial were just 4 degrees Celsius. A 100 ppm CO2 rise correlated roughly to a 250 foot rise in sea level and much warmer average conditions globally. A corresponding fall of about the same amount brought temperatures back down and piled ice two miles high over today’s temperate regions such as New York.

What the ice cores also revealed was that human CO2 emissions had pushed global levels of this potent greenhouse gas far out of any climate reckoning comparable to the context of human beings, who have only existed in current form for about 200,000 years.

In fact, what scientists found was that atmospheric CO2 levels were pushing more than 100 parts per million higher than at any time during this vast epochal span:

Ice Core CO2 record 800,000 years

(Antarctic ice core CO2 record and comparable temperature swings. Note that the difference between ice age and interglacial is about 8 C of local temperature and about 100 ppm of CO2. It is worth considering that, due to polar amplification, Antarctic temperature changes were about double the global average. Current CO2 levels are more than 100 parts per million higher than even the peak value over this 800,000 year period. If an average peak interglacial CO2 average of 275 ppm is considered, then current values are around 127 parts per million higher. Image credit: Havard/Jeremy Shakun.)

This record was a key contribution to climate science. One, it revealed how past CO2 levels compared to past temperatures. And since the data was directly derived from air bubbles trapped beneath hundreds of feet of ice, it also provided us with an exact measure for past atmospheres.

Secondly, and perhaps much more ominously, it showed us how very far beyond any climate comparable to that great span of time we’d already come.

102 ppm higher than at any time in the last 800,000 years

Humans have now pushed the CO2 boundary 102 parts per million higher than the context provided by the last 800,000 years. It’s kind of a big deal when you consider that a mere fluctuation of about 100 parts per million CO2 was enough, when combined with changes in orbital forcing, to set off feedbacks resulting in a 4 C temperature change globally (8 C change for the Antarctic environment) as ice age proceeded to interglacial and back.

Current human forcings through CO2 and other emissions have now entirely over-ridden the natural cycle, eliminating the possibility for future ice ages and putting us on a trajectory for catastrophe. With annual global carbon emissions now exceeding 12 gigatons, not only have we forced ourselves well outside of any past bounds to which we can easily relate, we have also generated an unprecedented velocity of change. For the current human carbon emission now exceeds, by at least six times, the most rapid past level of natural carbon emission.

No vast flood basalt could ever rival the volume and pace at which humans currently emit greenhouse gasses.

This enormous emission continues to have severe effect through an ever-higher ratcheting of global CO2 levels.

As of the past week, global daily CO2 values had rocketed to 402.2 parts per million, well outside anything seen in the ice core record:


(Mauna Loa Observatory CO2 measure for the last six months. Note that daily and weekly values have been mostly above 400 ppm since early March. Image source: The Keeling Curve.)

This an extraordinary measure. One that has no context in direct records such as those available to us through ice core data. But paleoclimate proxy data does provide some corollary. According to isotopic carbon measures found through seabed samples, we can determine that the last time CO2 levels were above 400 parts per million was during the mid-Plieocene between 3 and 3.3 million years ago.

And during that time global average temperatures were 2 to 3 degrees Celsius warmer than they are today (with Antarctic values at least twice that). Both Greenland and West Antarctica were mostly ice free and sea levels were between 15-75 feet higher. These are, likely, the potential low end of the changes we’ve locked in due to human global greenhouse gas forcing long term, even if, somehow, global CO2 levels are brought to a plateau.

Mid-Pliocene Antarctica

(An graphic extrapolation of Antarctica’s ice cover and elevation based on paleoclimate data. Note that the Antarctic ice sheet is greatly diminished at a time when CO2 values remained constant around 400 ppm. Image source: Commons.)

480 CO2e…

Unfortunately, the global CO2 measure doesn’t tell quite the entire story. For atmospheric levels of gasses like methane, nitrous oxide, and a host of less common industrial chemicals have also all been on the rise in Earth’s atmosphere due to human emissions. As a result, according to research by the Advanced Global Atmospheric Gasses Center at MIT, total heat forcing equal to CO2 when all the other gasses were added in was about 478 ppm CO2e during the spring of 2013. Adding in the high-velocity human greenhouse gas contributions since that time gets us to around 480 ppm CO2e value. In the context of past climates and of near and long term climate changes due to human interference, 480 ppm CO2e is nothing short of fearsome.

The last time the world saw such a measure of comparable atmospheric greenhouse gas heat forcing was during the Miocene around 15-20 million years ago. At that time, global temperatures were 3-4 C warmer, the Antarctic ice sheet was even further diminished, and sea levels were 80-120 higher than today.

This combined forcing is enough to result in a state of current climate emergency. In just a few years, according to the recent work of climate scientist Michael Mann, we will likely lock in a 2 C short term warming this century and a probable 4 C warming long-term. If the current, high-velocity pace of emission continues, we will likely hit 2 C warming by 2036, setting off extraordinary and severe global changes over a very short period.

These are very dangerous and, likely, catastrophic levels. In such a context, the inexorably rising rate of atmospheric CO2 and other greenhouse gas forcings simply adds further insult to a very high risk situation.


Havard/Jeremy Shakun

The Keeling Curve

Advanced Global Atmospheric Gasses Center at MIT

Far Worse Than Being Beaten With a Hockey Stick: Michael Mann, Our Terrifying Greenhouse Gas Overburden, and 2 C Warming by 2036


Pliocene Climate

Miocene Climate and CO2 Flux With Related Ecosystem Impacts


Leave a comment


  1. Mark Archambault

     /  April 11, 2014


    Great summary of the implications of 400 ppm and 480 ppm CO2e.

    You wrote; “With annual global carbon emissions now exceeding 12 gigatons…” Please correct me if I’m wrong, but I had thought we were now up to about 30 gigatons / year in emissions. Perhaps I’m mixing it up with another climate statistic.

    Only grammatical point is to reduce the use of the words “terrifying” and “terrifyingly”. Otherwise, this one’s a keeper, as they say.

    • Thanks Mark. CO2 is 30 gigatons. But you add in the weight of oxygen (one carbon + 2 oxygens). So the weight of the carbon component is approx 1/3. The total gigaton emission of all CO2e gasses is about 45 gigatons. Net carbon value is probably now 12-13 gt.

      Will do a quick edit otherwise.

  2. Mark Archambault

     /  April 11, 2014

    From the website Common Dreams: “21st Century’s First Decade Saw Doubling of Greenhouse Gas Emissions: IPCC” –

  3. Mark from New England

     /  April 11, 2014

    You wrote: “If the current, high-velocity pace of emission continues, we will likely hit 2 C warming by 2036, setting off extraordinary and severe global changes over a very short period.” – and to realize that 2 C is just a stepping stone to 4 C or more by century’s end. Can we even imagine how bad it’s going to get. I’ve come to the conclusion now that there’s no such thing as global warming alarmism. I’m sure that line will set the denialists hair on fire, but it’s the truth.

    Oh – and for a bit more anonymity (as if that means anything these days!), I’m changing my moniker to “Mark from New England”. Hat tip to ‘Colorado Bob’, who, I’m sure, is the only Bob in Colorado 😉

    • I long since stopped caring if people knew who I was. They can get in line if they have a problem 😉

      • Mark from New England

         /  April 11, 2014

        And I see you just posted yet another article – I think I know what you were doing in ‘your absence” over the last week! Best climate blog ever.

        • I have a whole boatload of stuff to catch up on! CPC just reported 65% chance of El Nino by November and their statement includes a ‘most powerful Kelvin Wave on record’ statement.

          Perhaps my wife will set me free to write one this weekend? I have to do a tally of my brownie points…

  4. It’s extremely close to game over from my perspective. The Arctic ice is the bellwether. If the summer ice goes, a canary is dead from a cage of canaries. If the Arctic becomes ice free all year around, then the entire cage is dead. W’re witnessing the extinction of humanity as a species. I’m not trying to be alarmist here: look at the Kevin Johnson’s work. For us to avoid a 2 degrees C rise, we have to cut radically NOW. For us to avoid a 4 degrees C rise, we have a few more years. This is not including the additional feedbacks.

    • Arctic sea ice is probably mostly gone at 1.5 to 2 C global warming. We’re at .8 C now and probably aren’t too far from ice free summer conditions.

      You’re right about rapid reductions. We need them now.

  5. Paul from NSW

     /  April 11, 2014

    Can someone give comment on the recent statements from James Lovelock. To my mind the evidence seems overwhelming, but here is someone who should know, now implying that it is probably not that bad. I know that some of his comments are being taken out of context by the deniers.

    • Lovelock told England to retreat to climate controlled domes, give up trying to control AGW since Britain’s not a world power anymore (leave to US and China), and that some technological means will be available for humans to escape our corporeal form (since that is really the source of the problem). This is what from the Telegraph. YMMV.

      He’s a bit of a maverick. So I think he had some interesting points. The let’s make us noncorporeal stuff is a bit futuristic but I don’t his position as supporting deniers. He’s in fact saying it’s going to hit us bad and we should head for the hills.

      • It’s kind of a retreat/bunkering mentality. A bad idea in my opinion. How long do artificial bunker cities last? My bet is not too long. See biosphere. There’s so much we take for granted that’s in our current environment. So many natural services that we fail to take into account.

      • I take your point about the bunker mentality (which is what it is, not that different from the nuclear mentality), but I think the Biosphere was mismanaged. I also think this is going to end up being the plan of last resort. This and living underwater and flying into space and all sorts of crazy stuff (unlikely to work). I’ve gotta tell you man, I don’t think there’s the political will to the cut the emissions back to the levels needed to stave off near term human extinction. I’m always optimistic and I’ll wait for the Arctic ice to completely melt before I give up, but it looks bad.

        I mean your essay just hits you in the guts — we’ve never been here and we’re not showing signs of stopping. Again, Kevin Anderson’s work on this is very clear.

        • We need to stop letting monied interests have their way. I suppose that’s what I mean by leadership. There’s no way out of this otherwise. Bunkering is basically a plan to fail, in my view.

          I agree that biosphere was probably done poorly. That said, the challenge of creating fully functional artificial environments devoid of beneficial outside inputs is a challenge human beings have not yet surmounted. If we were less focused on profits and gain for a few individuals and more focused on resiliency and broader happiness/well being, then perhaps we could achieve such goals.

      • Look at what’s happening with the Senate election. The Democratic politicians throw a bone here and there but they’re not that different either (though progressives I think have the best idea). How exactly can this leadership work? You mean someone like a Gandhi or MLK Jr.? We thought Obama would be a transformative person but he’s a nice guy who’s stuck being a figurehead. They’ve all been this way for a while. This country is largely an oligarchy. We do have people like Bernie Sanders and Elizabeth Warren and they too get sucked by up the system. I appreciate you sharing your views. I’m just wondering what our real chances are for getting out of this mess is.

        I think a country with a capacity to construct a nuclear submarine could do the biosphere within a couple of decades in a “put a man on the moon” kind of way. The only problem with the nuclear submarine is that there’s no food. so if we could do that is a self-sustaining manner, we could make it. Depending on the damage done to earth, we may be able to get out in a few hundred years or never.

        Itt is going to take hundreds to thousands of years for the system to recover from all the changes caused by us thusfar (this is a pure guess, if anyone has a good link on the damage assessment I’d like to know).

      • Mark from New England

         /  April 12, 2014

        Robert wrote in reply to Ram: “We need to stop letting monied interests have their way…”.

        And now the recent McCutcheon decision out of the US Supreme Court has just made fighting the monied interests THROUGH the system all that much more difficult, if not impossible without a massive political awakening as to how both parties benefit from the current arrangement.

        Therefore, effective resistance will likely require massive civil disobedience and actions like blocking the entrance to the Koch Brothers headquarters, etc. has organized events around the Keystone XL Pipeline, but I also believe there is a need for rapidly planned small scale actions to make the lives of those who profit from the destruction of the Earth a bit inconvenienced.

        Hello NSA, I don’t care if you’re listening…

  6. I just found this clip from a 1990 program called ‘after the warming’…

    • 26 years of the scientific community calling for action… 26 years of the fossil fuel industry getting on the way of action….

    • Bernard

       /  April 15, 2014

      Thanks for submitting, watched both episodes yesterday (they’re both on youtube). Much of his projected timeline is spot one if you allow for an error of a few years.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: