An Inevitable Headline in 2014: "Planet's CO2 level reaches 400 ppm for first time in human existence."

Sometime, about one year from now, the front pages of whatever decent newspapers are left will carry a headline like the one above, announcing that for the first time in human existence (or in nearly a million years, or 3 million years, or 15 million years), the global atmospheric concentration of carbon dioxide – the principal gas causing climate change – will have passed 400 parts per million.

That’s a significant and shocking figure. Unfortunately, it is only a temporary marker on the way to even higher and higher levels. Here (Figure 1 below) are the most recent (March 2013) data from the Mauna Loa observatory showing the inexorable increase in atmospheric CO2 and the rapid approach to 400 ppm.

Figure 1. The concentration of CO2 in the atmosphere measured by Scripps/NOAA at Mauna Loa. We're rapidly approaching 400 parts per million. Figure 1. The concentration of CO2 in the atmosphere measured by Scripps/NOAA at Mauna Loa. We're rapidly approaching 400 parts per million.

There is a range of estimates around the detailed time record of atmospheric composition, and the study of changes in atmospheric carbon dioxide concentrations over the billions of years of the Earth’s existence is an exciting area for research. A commonly cited figure with strong evidence comes from measurements of air trapped in ancient ice cores obtained from Antarctic ice. We now have a detailed 800,000 year record, which shows clearly that atmospheric CO2 levels never approached 400 ppm during this period (as shown in Figure 2).

Figure 2. The concentration of CO2 in the atmosphere, measured over the past 800,000 years. It never came close to 400 ppm. Present day is on the right of the curve. Figure 2. The concentration of CO2 in the atmosphere, measured over the past 800,000 years. It never came close to 400 ppm. Present day is on the right of the curve.

In December 2009, a research team from UCLA published a paper in Science that suggested we would have to go back at least 15 million years to find carbon dioxide levels approaching today’s levels. This research used isotopic analysis of shells in deep sea sediments and reported that CO2 concentrations may not have exceeded 400 parts per million since the Mid-Miocene Climatic Optimum (MMCO) – between 16 and 14 million years ago. The MMCO was associated with reduced planetary ice volumes, global sea levels a huge 25 to 40 meters higher than today, and warmer ocean temperatures. Decreasing CO2 concentrations after that were associated with substantial global cooling, glaciations, and dropping sea levels.

Gavin Schmidt of NASA’s GISS has pointed me to research in a December 2011 article in the journal Paleoceanography by Gretta Bartoli, Bärbel Hönisch, and Richard E. Zeebe reporting on paleoclimatic records that suggest that CO2 concentrations (at least in the Northern Hemisphere) may have been around 400 ppm between 2 and 4.6 million years ago. This evidence comes from isotopes measured in planktic foraminifer shells spanning 2.0 to 4.6 million years ago and indicates that atmospheric CO2 estimates during the Pliocene gradually declined from just above 400 ppm to around 300 ppm in the early Pleistocene 2 million years ago.

800,000 years ago? Three million years ago? 15 million years ago? More research will continue to clarify the variability of Earth’s atmospheric composition over time, as well as the impacts for the planet as a whole of screwing with it. [That’s a technical term…]

But the more important point to remember is that never in the history of the planet have humans altered the atmosphere as radically as we are doing so now. And the climatic consequences for us are likely to be radical as well, on a time-scale far faster than humans have ever experienced.

Peter Gleick

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A Reuters story about startling high levels of carbon dixoide in the air near the North Pole caught my eye this week. Levels of carbon dioxide, the main greenhouse gas from human activities, rose to 392 parts per million (ppm) in the atmosphere in Svalbard in December.... 392? That seems awfully…

Ugh. Here's an ugly addendum. A colleague has pointed to a new paper in PNAS that concludes:

"with CO2 stabilized at 400–450 ppm (as required for the frequently quoted “acceptable warming” of 2 °C), or even at AD 2011 levels of 392 ppm, we infer a likely (68% confidence) long-term sea-level rise of more than 9 m above the present. Therefore, our results imply that to avoid significantly elevated sea level in the long term, atmospheric CO2 should be reduced to levels similar to those of preindustrial times."

Nine meters....

That's sobering.

By Paul Weimer (@… (not verified) on 07 Mar 2013 #permalink

I'm scared guys, i'm really scared. Not specifically at this news, but at the fact that the majority of mankind still doesn't care. Even just the 50 year graph shown at the top already confirms that the rate of CO2 is actually ACCELERATING.

Can you say 450ppm by 2045?

Calm down - I have it on good authority from the heads of the automotive and energy industries that this is all nonsense. Even leading republicans will tell you this is rubbish. Also, if this really was important then prestigious media channels like Fox news would be running this daily,. Come on who would you rather trust, important people like these or "scientists" who only have "facts" to back them up?

The headline probably should come in 2014 (with global collation of CO2 data), but it will more likely come this year when the reading for Mauna Loa hits 400 ppm this May.

James Lovelock was predicting this effect in 2006 and earlier. Once the tipping point between negative and positive climatic feedback has been passed, chaos will probably ensue...

By Mike Waud (not verified) on 08 Mar 2013 #permalink

while one cannot but agree with the forecasts outlined here, it is also vital to understand the how and why we got ourselves into this fine mess, and why we will go on burning fuel until nature puts an end to it.
Prior to 1800, kings princes and bishops lived in castles and cathedrals because they had cornered the energy market. (our muscle power)
They were the idle rich, the rest of us peasants supported that idleness. A king could have his castle because he could order thousands of men to build it, stone by stone, by hand.
Starting in 1800 we burned 200 million years worth of fossilised sunpower in just 200 years, and suddenly everyone could live like kings, in warm houses, well fed and with our own personal transport. (those factors defined the aristocracy before 1800/1900)
What we thought of as man's genius was in fact taking a slice of the energy market for all of us.
We see this as our right, and demand that politicians maintain that right. If they don't, then there will be violent revolution. So our leaders sanction infinite fuelburning, they have no choice, as we have no choice but to try to maintain our 'way of life'.
This is why the deniers are listened to. Nobody wants to hear bad news, only that our good times can roll on forever.
What has in fact happened is that the planet has recognised humanity as an infestation, and is getting rid of us with the ferocity of heat wind and water

By endofmore (not verified) on 11 Mar 2013 #permalink

Excellent article Peter, not something I'm looking forward to seeing. Along with the initial Arctic Ice Cap melt out sometime this decade (it was at half the volume in 2012 that it was in 2009), some are guessing 2016 or so, humanity is going to get alot of visual numbers and picture warnings we need to take heed of.

As others have pointed out, we'll probably cross the threshold this year as the CO2 increase from Feb 2012 to Feb 2013 is much larger than the previous year and just adding that February increase to last year's May high pushes it past 400ppm (also the difference between 2011/2012 Feb readings was much smaller than the difference between the 2011/2012 May readings) so we may not just reach 400ppm but go past it some this year in May (ugly).

By Sasparilla (not verified) on 11 Mar 2013 #permalink

"End of More" is a brilliant meme, considering that some day it will probably be determined that plutocrats suffer from a neurophysiological disorder that impairs their "sense of satiety" (aka. the "enough" factor), producing their chronic craving for "more," as in, "endless increase of (whatever)."

Though, we can certainly have warm houses and clean water, hot showers, sanitation and transportation, etc.: all with clean energy sources such as thorium and renewables, and intelligent design (good engineering) of our public and personal infrastructure. What we can't have is growthism as our global religion, and an endless stream of consumer baubles, and overpopulation to go along with the overconsumption.

Some years ago I took the WWF "ecological footprint" data and came up with a rough estimate as follows:

At USA levels of impact, a global population of ONE to TWO billion is sustainable.
At Western European lifestyle, a global population of two to three billion.
At Eastern European lifestyle, three to four billion.

For six billion to live sustainably, a global average of Cuban lifestyle is necessary. There's enough to eat, everyone has the basics and a good education, but meat is a condiment rather than the main course at meals, private automobiles are for emergency workers only, and consumer baubles are rare luxuries.

We're at seven billion and the UN says we're heading for nine, but I say we aren't going to make it that far.

Whenever I hear someone argue that Thomas Jefferson's moral standing is impaired because he held slaves, I ask them how the future will look upon us for causing a human dieoff on a scale that will make the totality of 20th century holocausts and pogroms look like amateur hour by comparison. That's what we're heading for. That blood is on our hands.

Keyword search "diachronic competition" and contemplate the moral implications.

Humans adjust!
We can not change nature so we should be focussing on adjusting to new weather conditions etc as what has happened many times in the past. The world is going through a change, and not TAX will stop it!
How many ice ages and climate changes has there been ? The earth is overdue for a NATURAL change, IE another ice age!

Dazza, this is not right. Yes, humans can adjust, at least to some climate change. But the economic and social costs are likely to be vast, especially if we do nothing to slow the rate of climate change. In addition, what's happening now has NOT happened in the entire existence of humanity. We are NOT overdue for another ice age. The next ice age is not expected to begin for thousands of years. I've not made any arguments about policy, but a carbon tax would certainly have a positive effect: it would encourage emitters of carbon to cut back; it would raise funds to develop new innovative technologies for new energy or for adapting. Finally, you say we cannot change "nature." This isn't "nature." This is humans mucking up the delicate atmosphere that protects us.

Assuming all carbon stopped being pumped into the atmosphere, how long before we got back down to 350 ppm?

By conrad schmidt (not verified) on 15 Mar 2013 #permalink