Tundra, Part 2: The point of no return

What is the point of no return for the climate — the level of CO2 concentrations beyond which catastrophic outcomes are virtually unstoppable?

No one knows for sure, but my vote goes for the point at which we start to lose a substantial fraction of the tundra’s carbon to the atmosphere — substantial being 0.1% per year! As we saw in Part 1, frozen away in the permafrost is more carbon than the atmosphere currently contains (and much of that is in the form of methane, a far more potent greenhouse gas than carbon dioxide).

What is the point of no return for the tundra? A major 2005 study (subs. req’d) led by NCAR climate researcher David Lawrence, found that virtually the entire top 11 feet of permafrost around the globe could disappear by the end of this century.

Using the first “fully interactive climate system model” applied to study permafrost, the researchers found that if we tried to stabilize CO2 concentrations in the air at 550 ppm, permafrost would plummet from over 4 million square miles today to 1.5 million. If concentrations hit 850 ppm in 2100, permafrost would shrink to just 800,000 square miles.


While these projections were done with one of the world’s most sophisticated climate system models, the calculations do not include the feedback effect of the released carbon from the permafrost. That is to say, the CO2 concentrations in the model rise only as a result of direct emissions from humans, with no extra emissions counted from soils or tundra. Thus they are conservative numbers–or overestimates–of how much CO2 concentrations have to rise to trigger irreversible melting.

In short, those would-be points of atmospheric stabilization, 550 ppm or 850 ppm, aren’t stable at all — they are past the point of no return. We must stay well below 450 ppm to save the tundra and hence the climate.

Significantly, none of the major climate models — including NCAR’s (!) — included this crucial tundra feedback in their forecast of future concentrations atmospheric impacts for the IPCC. Thus, the 2007 Fourth Assessment Report by the UN’s Intergovernmental Panel on Climate Change underestimates greenhouse gas forcings and climate change this century — an especially worrisome situation given that the 2007 IPCC report was already incredibly dire (see “Absolute MUST Read IPCC Report: Debate over, further delay fatal, action not costly“).

Yet the IPCC report says that to stabilize below 450 ppm, the world must average under 5 billion tons of carbon emissions a year for the whole century. Annual carbon emissions are currently over 8 billion tons and rising 3% per year. We need to cut that to 4 billion by 2050 and below 1 by 2100.

And remember the tundra has some 1000 billion metric tons of carbon. In the future, losing a mere 0.2% per year of the tundra (in the form of CO2) would add two billion tons a year to our carbon emissions, yet that rate would still leave us with over 80% of the tundra by 2100, so it is not an especially fast loss rate compared to what we may see at 550 ppm or higher. And, of course, the greenhouse gas impact would be far greater if much of that carbon were released as methane.

The point is that once even a small fraction of the tundra begins to defrost, it makes efforts to stabilize anywhere near 450 ppm almost impossible. But again, should we get to 550 ppm or above for any length of time, then permafrost emissions (and other amplifying feedbacks) are likely to take us to 700 to 1000 ppm and beyond, which is the end of life on this planet as homo “sapiens” have come to know it (see here).

So the only prudent option is to stay below 450 ppm, which is eminently doable from a technological and economic, though not (yet) political, perspective (see “Is 450 ppm (or less) politically possible? Part 2: The Solution“).

Part 3 explores some recent research on destructive feedbacks that are internal to the tundra ecosystem.


33 Responses to Tundra, Part 2: The point of no return

  1. Ben says:

    Good god that was depressing.

  2. Earl Killian says:

    It helps to remember that Earth’s atmosphere originally contained no free oxygen. Earth’s second atmosphere was originally all nitrogen and CO2. Most of the CO2 became carbonate rock, but enough was converted by plants to O2 through photosynthesis. It now contains 209,460 ppm O2. 99% of that O2 came from the splitting of water by photosynthesis coincident with use of CO2 to make sugar and cellulose (this started about 3.3 billion years ago in bacteria). Much of that O2 went to oxidizing minerals (e.g. iron), so the amount of photosynthesis was larger than the 209,460 ppm suggests. The point is that somewhere on Earth are plant remains (carbon) sufficient to combust with 209,460 ppm O2. The tundra is just one small repository of photosynthetic storage. For example, the clathrates also hold enormous quantities of carbon (in the form of CH4). It would be much better if we don’t release them.

  3. kenlevenson says:

    Earl, so you’re piling on the good news this morning? ;)

    Perhaps off the mark – but looking at the graph above, knowing it doesn’t account for melting permafrost feedbacks (right?) – intuitively, it looks to me like, if we include those feedbacks, it would drop to zero by 2050. No? (Am I not reading this right? Or reading too much into it?)

    Scenarios are starting to make Lovelock look not so crazy anymore…but prescient.

  4. kim says:

    You can forget runaway catastrophes. Spencer, in a reply to the Great Raymond T. Pierrehumbert, at Pielke Pere’s site explain how the climate models all have climate sensitivity wrong. It is simple and elegant, the explanation, I mean.

  5. kim says:

    So you can chill. Emulate the earth.

  6. kenlevenson says:

    OMG….call me sally, but I didn’t realize there was a Sr. in the field too….

    Given this choice quote (quickly pulled from an abundance of possibilities) from Sr. on his 4-28-08 post:

    “The current focus of the IPCC and others on climate change with their emphasis on global warming, as a guise to promote energy policy, therefore, is an erroneous and dishonest approach to communicate energy policy to policymakers and the public. The optimal energy policy requires expertise and assessments that involves a much broader community than the climate science profession.” linky –

    Is it me, or does it feel like an Irving Kristol/Bill Kristol thing going on? No?

    It’s all much clearer to me…thanks Kim.

  7. Dano says:

    It is simple and elegant, the explanation, I mean.

    What is also simple is the typical seizure by the denialist crowd to grasp the latest of anything that they hope validates their ideology. Many times they have done this, many times we see that time has told us of this tactic (CRF being the latest).

    What science does, as Spencer says, is look at work and test it in different ways. Has anyone taken Spencer’s work to heart on their models yet? No? Then we don’t know whether he is right or wrong*. Therefore we can’t use a blog post or single paper as evidence yet.

    In the meantime, society has moved on and is debating adaptation and mitigation strategies. That’s right: what will we do in the face of future warming (much of it man-made, as Spencer says is plausible)? That’s what society is discussing now. Will the future decision-making be better informed when modeling is more robust? Certainly.



    * Note to denialists: this does not mean I reject Spencer’s findings. Don’t try to make it sound as if I do.

  8. Dano says:

    kenlev pulls out the nut:

    The current focus of the IPCC and others on climate change with their emphasis on global warming, as a guise to promote energy policy, therefore, is an erroneous and dishonest approach to communicate energy policy to policymakers and the public.

    RP Sr finally comes out and says it. Certainly his hobbyhorse of land-use change is a component of man-made climate change, but a minor part and not all of it.

    The current energy policy of most countries on this planet looks likely to be a major component of the recent man-made climate change, so it is entirely appropriate to communicate an approach to alter current energy policy to avoid additional climate impacts.

    IOW: RP Sr sez doublespeak buncombe.



  9. exusian says:

    kim Says: “It is simple and elegant…”

    And wrong.

    As usual.

  10. Gestur says:

    And when I look at this graph, it appears that from 1900 to 2000, the permafrost area has declined from 12 (or you could take 13 a little later) millions of km^2 to something like 10 millions of km^2. Using the 13 to 10 rate, that’s about a 0.26% annual rate of decline over this 100 year time period, and it’s about a 0.18% annual rate of decline using the 12 to 10 endpoints. So those rates of loss of area have been experienced already, it appears.

    I have no knowledge of the intensity of CO4 release from the permafrost and into the atmosphere arising from this loss area of permafrost—is all permafrost equal?—so that loss of area doesn’t necessarily translate into released CO4 of similar rates. But isn’t it likely that this historical loss has resulted in some CO4 emissions?

    Given this, and as a point of clarification, I think a better tack to take would be to discuss the much larger magnitude of the loss possible under various temperature rising scenarii. Again just eyeballing this graph, it looks like the SRES A2 would decline to around 3.5 millions of km^2 by 2050, which is again about a 2.1% annual decline, or some 11 times larger than the 0.18% decline. Even the SRES B1 looks to decline to 5 millions of km^2 by 2050, which is again about a 1.4% annual decline, or some 7.6 times larger than the 0.18% decline. Both of which are huge accelerations in the rates of loss of permafrost and hence potential release of CO4.

  11. Ronald says:

    I agree with Ben when he says that looks depressing.

    We had in our large local newspaper an editorial from George Will about how we don’t have to worry or even think about global warming, all the worry is about some Polar Bears dying and we should just decide to not hunt them, everything would be fine. I wish our newspaper would have articles about this subject from people explaining the real dire possibility of catastrophe from those who can explain that kind of stuff instead of stuff writing that stuff from a longtime political hack.

    How should we look at Global Warming, with pessimism or optimism? I sure do think that many try to never think that we may be giving future generations trouble. We do in our minds look at them with the mental filters we evaluate all information with. I think I try hard to look at it with realism, not pessimism or optimism. But if these studies are realism, all that realism is sure depressing.

  12. kim says:

    exusian, it is simply amazing how well you’ve demonstrated Spencer and me to be wrong.

  13. Tom G says:

    Something that troubles me is the methane coming from the Siberian permafrost during the winter.
    My understanding is methane comes from “wet” permafrost. Frozen bogs.
    Yet these bogs continue release the gas even when they should be re-frozen during the winter.
    Could these be small pockets of gaseous methane trapped in these areas?

  14. kim says:

    Dano won’t know what to think of Spencer’s paper until someone tells him.

  15. exusian says:

    And when did the troll known as kim ever demonstrate anything?

    Try the RealClimate post on Spencer for all the demonstrating a rational person needs.

  16. Greg N says:

    A news report from the BBC today is an interesting read – there are indications that the Arctic region is responsible for last year’s methane increase

  17. kenlevenson says:


    To follow on your clathrates comment – did you see this New Scientist article? (subscription for the whole thing)

    “Perhaps the greatest threat of an unexpected release of carbon from the deep comes from an indirect effect of human-made CO2. Global warming could destabilise some deep carbon reserves, notably in clathrates – ice lattices which are found beneath the ocean floor and continental permafrost, and even under freshwater lakes like Lake Baikal in Siberia (pictured). These ice structures may hold trillions of tonnes of methane. …
    “If you raise temperatures even slightly, they could be released.” According to Ronald Cohen, a geophysicist at the Carnegie Institution, natural warming caused large releases of methane around 55 million years ago.
    …Though the deep carbon cycle could theoretically absorb human-made emissions, Hazen points out that this would take millions of years. Catastrophic methane emissions could happen over just a few decades….Natural processes such as volcanism are also known to bring carbon to the surface, but there may be other mechanisms to release buried carbon that have not been considered by mainstream climate science. For example, there is growing evidence that microbes living deep in the crust may be converting carbon into forms that can migrate to the surface – notably methane.”

    Joe, perhaps another feel good series on clathrates?

  18. Scott M. says:

    Tundra thawing has directly demonstrated for the last interglacial, and by inference, for previous warm periods between ice age maxima over the last couple of million years. See for example Pewe et al., 1997, GSA Special Paper 319, “Eva Interglaciation Forest Bed, Unglaciated East-Central Alaska”. From their abstract: “…the warm interglacial was characterized by deep and rapid thawing of permafrost and erosion of loess … ” Pewe et al. document white spruce stumps and logs that were up to 200 years old at time of burial under what is now present-day tundra. Being as how white spruce does not grow on permafrost, the terrane must have been thawn out for centuries (if not millenia) at the height of the last interglacial.
    And yet, the world didn’t end … :-/

  19. Traddles says:

    Scott M., it’s like George Carlin says, “The planet’s going to be fine…it’s humanity that’s fucked.”

  20. David B. Benson says:

    Scott M. wrote “… the terrane must have been thawn out for centuries (if not millenia) at the height of the last interglacial.” I doubt this is necessary for white spruce. I suspect it suffices for the ground to thaw to just below root depth.

    Have you references?

  21. Joe says:

    Greg — nice catch. I’ll stick it in the next post.

  22. Robert says:

    If you are considering very long timescales then the sun’s luminosity becomes an important factor. 500 million years ago the sun’s luminosity was 6% less than today:

    The Gaia hypothesis suggests that the earth regulates its temperature by modulating atmospheric CO2. The recent natural level of 280ppm is low historically, but this may be because “Gaia” is fighting a losing battle against the long term rise in luminosity. In which case we are playing with fire by artificially raising CO2 at all. No level should be considered safe, and certainly not 450 ppm+

  23. Dano says:

    500 million years ago the sun’s luminosity was 6% less than today:

    And the moon was much closer, exerting much more tidal force on the earth.

    Personally, I’m polluted with an ecological education & I’d say Gaia adapts rather than modulates. She’s not moving the moon away & lessening volcanism as a result. But that’s just me.



  24. kim says:

    Interesting, Robert. I’ve wondered if the interworkings of the biosphere with the sun have kept the earth perched near the edge of glaciation. Vulcanism is the source of CO2 and critters, powered by the sun, virtually permanently sequester carbon as hydrocarbons and carbonates. As the earth heats, the biosphere goes into high gear, and as it cools and ices, it goes into granny. This is a self-regulable cycle. Keeping us on the cusp of glaciation is a marvelous response to the gradual increase in insolation.

  25. paulm says:

    ….No one knows for sure, but my vote goes for the point at which we start to lose a substantial fraction of the tundra’s carbon to the atmosphere —…..

    I would say from the graph we are pretty much there. The next 18 months will tell. It was pretty much the same for the arctic sea ice. I mentioned on seeing the graph, posted in here, that it looked like it had tipped for 2007 – well they are now saying an ice free arctic next year!

    These graphs are scary, but many (even those in the know) seem to be in denial as to the catastrophic message they are portraying.

    The permafrost melt is pretty dire – I don’t see how higher concentrations of CO2 are avoidable now, what ever action we take.

  26. Reader says:


    The Gaia hypothesis also places us humans within the system or superorganism. In what way do you suppose our actions are ‘unnatural’ and a cause for concern? Is it possible we just aren’t seeing the big picture?

  27. David B. Benson says:

    Gaia doesn’t care about whole families that go extinct, much less mere genera and species. I don’t think you can count on Gaia to do anything as Homo Spaiens self-distructs.

  28. David B. Benson says:

    Oops. ‘Homo sapiens’

  29. Greg N says:

    Oops. ‘Homo sapiens’

    That’s what the planet’s saying.

  30. kim says:

    No, Greg, that’s what the people who think the world is overpopulated say. Quite a little dilemma of identity they face, and they are facing it disreputably, so far.

  31. David B. Benson says:

    The Holocene is termination 1. The Eem/Sangamon is termination 2. Looking back in the Vostok ice ccore record, termination 4 was far warmer than the following three.

    Somehow, I can’t (yet) get too excited about a small amount of methane release.

  32. kenlevenson says:

    Relatively small compared to what is coming perhaps – but according to Fred Pearce Siberian melt is already releasing the equivalent of ALL U.S. man made GHG emissions….that evokes a “holy sh*t” in my mind.,+which+meant+a+warming+effect+on+the+planet+greater+than+that+of+all+the+U.S.&ei=GfQ1SLzkDJyUywTI_5XqDw&client=firefox-a&sig=7dT3ovC7HTREtjtsHdn2l5rQUpo

  33. Aaron Lewis says:

    This site remains wildly cheerful by excluding the unpleasant concept of warm plumes of North Atlantic water intruding into the Arctic and liberating clathrates.

    If you suffer from an unbearable sense of joy, pour yourself a large glass of absenth and read the 2008 report from :

    Then, and only then, you may drink the absenth.