Irreversible Does Not Mean Unstoppable

A translation in Chinese is available here.

210 comments on this post.
  1. Slioch:

    Typo: “carbon molecules”
    Presumably “carbon dioxide molecules” or “carbon atoms”.

    [Response: Well the carbon comes in different forms, so I changed it to ‘carbon-containing molecules’ – which should cover everything. – gavin]

  2. Maiken:

    Thank you for giving us hope, even though a small hope it is! But if we do not act upon the hope we still have, then there won’t be any reason for hope left to work with later. What I struggle tremendously with is how to best communicate the tremendous urgency in a way that it activates people, without seeming to be an alarmist or spreading stiffening fear.
    One way to better communicate what awaits us in case of inaction, and what is needed and possible to avoid passing tipping points, could be models that internet users can play with to see for themselves what will happen under which assumptions. One such model I just found on the Yale webpage (
    If you know of other webpages on which people can play with different climate or economic models, could you please post them here?
    Thank you very much!

  3. Alastair McDonald:

    Well, all I can say is that you have excelled yourselves in this post. It is nothing but denialist rubbish.

    You state:

    It is not really news scientifically that atmospheric CO2 concentration stays higher than natural for thousands of years after emission of new CO2 to the carbon cycle from fossil fuels.

    So that is all right then. We don’t have to worry unless the levels of greenhouse gases increase. How are you going to prevent that. Stop burning all fossil fuels? That is the only way!

    The Arctic sea ice is retreating and the glaciers are melting worldwide. This will reduce global albedo and raise sea level temperatures, so the oceans will release more CO2 even if we stop adding fossil fuels now.

    When are you going to face up to the fact that the world is heading for disaster. Unless we take panic measures we are all doomed.

    Cheers, Alastair.

    [Response: – gavin]

    [Response: I agree, stopping burning fossil fuels is the only way. I’m not sure where you think we disagree. David]

  4. Richard Pauli:

    Wonderfully hopeful. Thank you.

    Humans have made resolute decisive actions in the past, so the required change is possible.

    Most perplexing is why we are not moving faster.

  5. Ark:

    Without underestimating the challenge of going carbon-neutral globally: that’s not the limit! If after phasing out coal-fired power plants, we start using their Carbon Capture & Storage units to capture and store CO2 from biomass-fired power plants (bio-residues, algae etc.), we can effectively introduce negative CO2-emissions.

    [Response: In principle, yes. In practice: the German Advisory Council on Global Change made an estimate of the global potential for this in its recent report on bioenergy (page 136, so far only available in German). At best you can reduce the atmospheric CO2 concentration by 9 to 18 ppm over a century in this way. So, I wouldn’t count on it. It is far easier to avoid CO2 emissions than to get the CO2 back out of the air. -stefan]

  6. Chris Colose:

    Good post

    For further clarification on “unstoppable” Solomon et al. note “where irreversible is defined here as a time scale exceeding the end of the millennium in year 3000; note that we do not consider geo-engineering measures that might be able to remove gases already in the atmosphere or to introduce active cooling to counteract warming).”

    Matthew and Caldiera 2008 (in GRL) also speak of irreversible climate change on human timescales, and conclude that elevated temperatures may not decrease significantly for half a millennia even if emissions dropped to zero soon.

  7. Ray Ladbury:

    David, thanks for this as a counter to the sort of “It’s hopeless, so I don’t have to do anything” idiocy that has greeted this story. It seems that the denialosphere is willing to embrace science only so long as they can use it as an excuse for inaction.

    One thing that has concerned me. If you look at the past 10000 years, the two most notable developments have been remarkable climatic stability and the emergence of human civilization. It seems that it could well be argued that the former may have been a prerequisite for the latter, since it shifted the balance so that people could grow more calories via agriculture than they could hunt and gather.

    If climate change brings an end to that stability, it could well mean that human population cannot be sustained at even a tenth of current levels. Moreover, even if we developed advanced geoengineering solutions that brought us back down to 280 ppmv CO2, it’s not clear to me that we would necessarily return to a pattern of climatic stability. Have any modeling efforts looked at this question?

  8. Colin:

    First, thank you, Maiken, for the link to the Yale model. I look forward to exploring that later when time allows. Secondly, I’ll express thanks to all you guys at RealClimate for truly outstanding work. However, I have to take exception to a couple of points not necessarily reflected in your latest post.
    First, virtually everything I read, here and elsewhere, seems to a great extent based on the paleo-climatologic record deduced from ice and sediment cores among other sources. While I have no doubts about that data or the resultant deductions, I am extremely dismayed that no one seems to “realize” that those conditions took place without the anthropogenic “forcing” we are currently witnessing. Therefore, what is happening now is unprecedented and “relying” on past changes to model what is to come is, at best, weak and a gross underestimate. I think there is support for this view in the Arctic melting of the past couple years researchers have proclaimed “decades ahead of the worst case models.”
    Secondly, I am further concerned that I don’t hear or read anything regarding the role of thermodynamics in these events. Specifically, those “laws” indicate that the greater the differential between a “hot source” and a “cold sink” the greater the rate of heat-flow. Especially since it is “well known” that water is so much “better” than air at conducting heat. This appears to be supported by the reported thinning of the “permanent” ice in the Arctic as well as the declining volume. I anxiously look forward to the data and reports from the “yellow submarine project” at the southernmost continent.
    Lastly, while it is reported that sea-level is rising “slowly,” I find nothing regarding the subsequent effect on the “floating” ice shelves. Being a scuba diver and a “fan” of Archimedes I am keenly aware that for every 33 feet of depth a submerged object will experience an increase in pressure of 1 atmosphere (~14.7 psi). So, a straight forward calculation will show that for each inch of sea level rise, there is a corresponding increase of buoyant (upward) force in excess of 74,000 tons on every square mile of shelf. It seems to me that this should be of particular significance, especially when “coupled” with the thermodynamics.
    If anyone could offer any “clarification” or let me know how/where I may be flat-out wrong I will be most appreciative. Thanks.

  9. Geoff Beacon:

    The only long-term way to accelerate the CO2 drawdown in the long tail would be to actively remove CO2 from the air, which I personally believe will ultimately be necessary.

    — We can remove CO2

    As a result of the long tail, any climate impact from more CO2 in the air will be essentially irreversible.

    — We can’t.

    [Response: We can but it’s hard. David]

    Isn’t methane different? Cut emissions and the level in the atmosphere goes down because of the OH sink. My quick reading of the relevant section in AR4 ( “ Changes in lifetime”) seems to indicate this sink doesn’t vary much with the concentration of methane. Have I got this correct?

    [Response: The lifetime of methane is thought to go up with an increase in the emission flux, because of limitation by availability of OH. So the steady-state concentration goes up somewhat faster than a linear dependence on the emission flux. Not a huge effect, but not negligible either. David]

    This paragraph suggests that any extra methane does not directly increase the OH sink so the “queue of methane” waiting to be removed simply increases by this extra amount. Until slower effects kick-in, such as extra water vapour from global warming, this gives the “extra methane” (or “marginal methane” in the language of economists) an unlimited lifetime.

    P.S. An earlier attempt to ask this question got the answer “all methane is equal”. I hadn’t bothered with the mixing (or queue jumping) issue because I thought the physical climatic should be the same with or without mixing.

  10. Geoff Beacon:

    Perhaps some of my last post was rather convoluted. Put more simply:

    If methane emissions exceed the capacity of the OH sink, we are in trouble. But is the sink independent of methane concentrations?

    Is all this well known?

  11. Jim Cross:

    I’ve read something recently about the regrowth of tropical rain forests due to abandonment by farmers.

    I assume this is positive impact, but suspect it not much of one. Has anyone assessed how much of an impact this could be?

  12. Chris Colose:

    I do have a question: has anyone looked at various trajectories of land use/deforestation, etc and any other secular changes in geochemical boundary conditions over the coming century to see at what kind of atmospheric concentrations CO2 would “re-equilibirate” to following sufficient time of zero anthropogenic emissions?

    In other words, there is nothing special about “280 ppmv” that should make it a default baseline to which we will inevitably return, but that seems to me to be a function of the current biospheric state and agriculture (or perhaps any long-term changes in ocean chemistry which stay affected longer than the CO2 residence time). To what extent would such changes such as land modification make “300 ppmv” or “320 ppmv” a new baseline (i.e., a new “natural background”) to which we would re-equilibriate given enough time for anthropogenic CO2 removal?

  13. John Mashey:

    Yes, and really, people should go read the book, and maybe even help out by adding another review or two… as it’s not just for RC readers, but a good “start here” recommendation.

  14. Leonard Ornstein:


    You say: “The only long-term way to accelerate the CO2 drawdown in the long tail would be to actively remove CO2 from the air, which I personally believe will ultimately be necessary. But the buffering effect of the ocean would work against us here, releasing CO2 to compensate for our efforts.

    As a result of the long tail, any climate impact from more CO2 in the air will be essentially irreversible.”

    Your emphasis, as well as Solomon’s remains misleading and self-contradictory.

    Focus on terms like “essentially irreversible” and “unstoppable” will mislead policy makers and the public by leading them to believe that significant drawdown is for the future – or simply impossible!

    Your belief that NET removal, (“drawdown”) of CO2 from the atmosphere “will ULTIMATELY be necessary” is simply wrong!

    Drawdown is necessary NOW, and therefore should be at the center of discussions on mitigation. And drawdown now IS possible.

    As you noted, by acting now, we largely avoid the bulk of the buffering delay.

    In this connection, I have 2 papers in the pipeline a Climatic Change, that describe about 8 to 13 GtC/yr (8 to 13 wedges) of affordable ‘bio-sequestration’, that require only already mature technologies; one involves irrigated afforestation of sub-tropical deserts, and the other, sustainable eco-neutral conservation harvest of old-growth tropical forests.

  15. Jim Redden:

    Very informative post. Thanks for that.

    David does not mention his very relevant book in the context of his post, so I will:
    The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate

    Anthropogenic climate change is discussed in the revealing framework of geologic time, and past and present time periods are considered–a relatively easy read as climate books go, and very apropos to the discussion due to the long time scales looking forward and backward.

    Issues of the residency of CO2 in the atmosphere and ocean are discussed (the long tail of emissions). The Dryas event, along with HO cycles are explored/explained too. Of course, references to the peer reviewed literature are included for anyone who wants to go further to build upon what they’ve learned.

    I still believe the big surprises are yet to come from the biogeochemical cycles of the ocean related to plankton lifecycle and acidification–not good ones at that–long before we get close to exhausting hydrocarbon fuel sources. Hope I am wrong.

  16. Steve Albers:

    Interesting to see this paper and I’m gaining new perspective that a 20% figure for the carbon remaining in the oceans translates into double that (40%) for the enhanced atmospheric CO2 concentration. That really does make the warming effect stay at its present level of enhanced temperature (due to ocean heat storage), even if all emissions are cut.

    Now we will need to learn more about how much CO2 can be sequestered in the soil and vegetation.

  17. Steve Albers:

    Hi – please note my previous post (I think #14) should read \20% figure for the emitted carbon remaining in the atmosphere\

  18. Mark J. Fiore:

    Hi. I post here at RealClimate a few times per year.This is a great post,as usual. Lots of good info.
    The Earth will not stabilise at 350ppm. Nor 450 ppm.Nor 550 ppm. My research indicates that co2 has an excellent chance,no, let me rephrase that, a formidable chance, of stabilising at 650 to 1000 ppm.Above 850 ppm the oceans become anoxic, and outgass methane. See Peter Ward’s work.There is no hope of stabilising below 650 ppm, unless worldwide, mammade, human co2 emissions were to fall 80% below 1990 levels, right now. End of story.
    Mark J. Fiore

  19. Rod B:

    A couple of secondary detail questions: (1) Isn’t rock the predominate CO2 absorber in the long run (over 1000 yrs. min; probably in the 10s and 100s of thousand yrs.) and in this scenario wouldn’t it be rock absorbing most of the decreasing tail? (2) Is the delayed absorption by the oceans what the “time constant” discussion a couple of threads back was about?

    [Response: Yes, ultimately CO2 returns to the solid earth by reaction with the CaO component of igneous rocks, a negative feedback system that stabilizes the climate of the earth with a time constant of hundreds of thousands of years. The time scale for equilibration with the ocean is a few hundred years. David]

  20. Geoff Beacon:

    Perhaps some of my last post was a bit convoluted. Put more simply: If methane emissions exceed the capacity of the methane sink, we are in trouble. But is it fixed?

  21. Pat Neuman:

    Saying we

    “have to remember that the climate changes so far,
    both observed and committed to, are minor compared with the
    business-as-usual forecast for the end of the century” …

    downplays what we’ve already been set in motion, in my view, even with the comparsion.

  22. D iversity:

    In one form or another there probably will be a practical means of taking greenhouses gases out of the atmosphere available before the end of this century; and it will probably be difficult and damned expensive. It just might be cheap and easy; but the fat tail is that it won’t be there at all.

    Stopping making the problem worse remains the policy choice tha twe are least likely to regret.

  23. Roberto:

    I fail to understand why somebody in science would use the word irreversible which has a very definite meaning in the real world as well as in science, to characterize a time scale of a millennium. Nobody working on this topic did it before, and I am sure there must be a reason for doing it now.

  24. Gail:

    Actually, the aggregate of studies indicate that we have already heated and polluted the earth well beyond unstoppable, and that the newer studies indicate that feedback effects are outpacing even the most recent predictions.

    [Response: Serious as this is, it is not all driven by climate change – indeed it is more serious because it is not linked to any one of the multitude of impacts humans are having on ecosystems. – gavin]

  25. Nigel Williams:

    Great post! Solomon et al say:

    “Some recent studies suggest that ice sheet surface mass balance loss for peakCO2 concentrations of 400–800 ppmv may be even slower than the removal of manmade carbon dioxide following cessation of emissions, so that this loss could contribute less than a meter to irreversible sea level rise even after many thousands of years (44, 45). It is evident that the contribution from the ice sheets could be large in the future, but the dependence upon carbon dioxide levels is extremely uncertain not only over the coming century but also in the millennial time scale.”

    I’ve read the Abstracts of the papers referenced,

    44. Charbit S, Paillard D, Ramstein G (2008) Amount of CO2 emissions irreversibly leading to the total melting of Greenland. Geophys Res Lett 35:L12503, 10.1029/2008GL033472.

    45. Parizek BR, Alley RB (2004) Implications of increased Greenland surface melt

    Charbit et al note that: “The long-term response of Greenland to anthropogenic warming is of critical interest for the magnitude of the sea-level rise and for climate-related concerns. To explore its evolution over several millennia we use a climate-ice sheet model forced by a range of CO2 emission scenarios, accounting for the natural removal of anthropogenic CO2 from the atmosphere. Above 3000 GtC, the melting appears irreversible, while below 2500 GtC, Greenland only experiences a partial melting followed by a re-growth phase. Delaying emissions through sequestration slows significantly the melting, but has only a limited impact on the ultimate fate of Greenland. Its behavior is therefore mostly dependent on the cumulative CO2 emissions. This study demonstrates that the fossil fuel emissions of the next century will have dramatic consequences on sea-level rise for several millennia.”

    Wiki gives us that:
    …the atmospheric CO2 content is currently approximately 3 teratonnes.

    Which is saying that we are at or inevitably soon to be at the 3000GtC that Charbit et al found means the “…melting [of all Greenland] appears irreversible”.

    [Response: I think Charbit meant 3000 GtC of emissions, not the total mass in the atmosphere. We have already emitted about 300 GtC. David]

    In the abstract for
    Implications of increased Greenland surface melt under global-warming scenarios: ice-sheet simulations, Parizek BR, Alley RB (2004)

    they note that “The Greenland ice sheet is likely to make a faster contribution to sea-level rise in a warming world than previously believed, based on numerical modelling using a parameterization of recent results showing surface-meltwater lubrication of ice flow. Zwally et al. (Science 297(557) (2002) 218) documented correlation between increased ice velocity and increased surface melt (as parameterized by positive degree days). They argued that surface water is piped directly to the bed with little delay, causing increased basal-water pressures and basal-sliding velocities, an effect not included in recent Greenland ice-sheet models known to the authors.”

    So what do Solomon et al mean when they say: “…the contribution from the ice sheets could be large in the future, but the dependence upon carbon dioxide levels is extremely uncertain …”

    The dependence (and hence the likely contribution and timing) looks pretty clear to me – what am I missing? Why the hesitation?

    (Captcha: to improve tears!!!)

  26. SecularAnimist:

    David wrote: “Perhaps the despair we heard in our interviewers’ questions arose from the observation in the paper that the temperature will continue to rise, even if CO2 emissions are stopped today. But you have to remember that the climate changes so far, both observed and committed to, are minor compared with the business-as-usual forecast for the end of the century. It’s further emissions we need to worry about.”

    As I understand this study, the take-home message is that whatever turns out to be the peak level of atmospheric CO2 by the time we stop increasing it, is the level we will be stuck with for a long time — and we’ll also be stuck with whatever amount of anthropogenic warming accompanies that level for a long time.

    Therefore it is very important that CO2 levels peak at the lowest level possible. Which in turn means that our CO2 emissions — which are currently accelerating — need to peak as soon as possible, and then decline as rapidly as possible.

    So, yes, of course we need to worry about future emissions and do everything possible to slow, stop, and reverse the currently accelerating increase in emissions.

    However, the other thing I take from this study is that at a minimum, the current levels of CO2 and the warming and climate change effects from those levels that we are currently experiencing, are with us for the long term — including, for example, melting ice caps and glaciers. There is no possibility of stopping these effects let alone reversing them, even if the warming levels off and stops at current temperatures — because current temperatures are sufficient to cause these effects, even without any additional warming.

    And given the nature of the effects we are already seeing — including evidence of self-reinforcing feedbacks already kicking in — that is certainly a reasonable basis for “despair”.

    I’d be very happy if someone can explain to me that I’ve got this all wrong.

  27. Hank Roberts:

    Half wrong, Sec, look up Charney climate sensitivity.

  28. Gail:

    Gavin, thank you for your excellent point. Of course, there are many different ways humans have of driving species to extinction, not only emissions of greenhouse gasses. And I think the larger issue is that although indeed humans are despoiling our planet in many ways, the most dangerous is climate change because of the exponential impact from feedback loops, such as the melting of the polar ice and, my own particular favorite, deforestation which could easily lead, through even further warming and drying of the soils, to desertification. From my own personal observations on the US Eastern seaboard, this process is well underway and it is irreversible, in the sense that once trees show signs of senescence, which ALL of them do (thinning crowns, singed leaves, yellowing and dropping of needles, rotting limbs) it indicates that the roots of the tree are already so damaged that the tree cannot be saved.

    Although I am not a scientist I have been wading through as much technical research as I can locate, and I have yet to find the exact culprit. It could be blamed on warming, drying, soil nutrient depletion from acid rain, pollution, ozone levels, some other factor or a combination.

    In any event, the sudden and rapid demise of deciduous and coniferous trees is not an encouraging sign for other vegetation, such as food crops.

    I am not an advocate of giving up, although I’m quite gloomy. I think the emphasis must be on stopping emissions, green energy, developing technology to clean the atmosphere, and preserving as many life forms as we can for future propagation.

  29. Steve Albers:

    I think you’re close SecularAnimis. It’s that the current warming amount is locked in for a long time, along with 40% of the present CO2 concentration enhancement.

  30. Igor Samoylenko:


    Hansen et al (2008) estimated the cost of removing CO2 out of the air artificially at $10 tln per 50ppm of CO2 ($100 per one ton of carbon). You noted that when we attempt to do it, the oceans are likely to work against us by releasing more CO2 into the air.

    So, is this figure of $10 tln really the minimum cost of artificially drawing 50ppm of CO2 from the air and the real cost is likely to be higher, potentially much higher (i.e. if we are to try to remove carbon from the long “tail” of 30% of CO2 left after the oceans take up the initial 70%)?



    [Response: I don’t know the details of Hansen’s calculation. It’s an interesting question, the ocean will make a huge difference to the answer one would get. David]

  31. Dave Hume:

    Firstly I am not a scientist,but what is bothering me is the boiled egg syndrome. As the water heats up the white of the egg hardens and as it pentrates deeper the yolk solidifies. My conclusion is that there will come a point in time when the core of the earth begins to manifest in increased volcanic activity, seismic events etc. Without the polar Ice Cap reflecting the heat away. and greenhouse gasses traping the heat, and the methane release already happening, how long before we are plunged into another ice age due to multiple volcanic clouds covering the planet.

    We have recently had a disasterous tusunami in the indian ocean and also the quakes in pakistan, and the current volcanic activity in the north.

    I live in South Africa and I am now almost 62 years old, I have four grand children , the eldest is almost 3 and the future looks very bleak for them.

    I run a Christian Debating forum , which I also use to promote climate change conciousness, and our God given responsibility to manage the planet.

    In South Africa we have already experienced some loss of our coastline due to abnormal high tides. Also Last year we had almost 8 months of continuous rain , something I have not experienced in the past, also this year we have had flooding again. One of a news reports called it a killer storm.

    I have written to some of our many political parties, to create awareness, yet our semi state controlled media has no real meaningfull coverage on the climate debate.

    I think pandoras box is already open, and I dont think we can close it again.

    Yours in Christ


    [Response: The impact of climate change on seismic events/volcanoes/tsunamis etc. is not something one needs to worry about – the forces controlling those phenomena are vastly in excess of anything we will be able to do to the Earth’s crust. There is possibly an exception to this related to changes in isostatic loading associated with melting ice sheets, but even there we have a very long way to go. There are important stewardship issues raised by the CO2 problem, but this is not likely to be one them. – gavin]

  32. G.R.L. Cowan, H2 energy fan until ~1996:

    In one form or another there probably will be a practical means of taking greenhouses gases out of the atmosphere available before the end of this century; and it will probably be difficult and damned expensive. It just might be cheap and easy; but the fat tail is that it won’t be there at all.

    True if “fat tail” means impossibility. Permanent CO2 removal on an industrial scale has already been inadvertently demonstrated. Also see olivine-related comments in Air Capture.

    — G.R.L. Cowan, (How fire can be domesticated)

  33. Nigel Williams:

    ..and further to my last post (1 February 2009 at 4:01 PM), can you also elucidate on what Solomon actually says in the first part of the quote above:

    “Some recent studies suggest that ice sheet surface mass balance loss for peakCO2 concentrations of 400–800 ppmv may be even slower than the removal of manmade carbon dioxide following cessation of emissions, so that this loss could contribute less than a meter to irreversible sea level rise even after many thousands of years…

    The quoted studies seem to show the opposite.. ?

    This is a very important paper, and I’m keen to thoroughly comprehend it’s meaning. The other sections on temperature, precipitation and inevitability etc are quite clear – but the sea level rise section is (at least to me) harder to get to grips with.


    [Response: I think it’s an open question what the response of the ice sheets will be during the time period of the CO2 peak. The impacts of the tail are much easier to predict. David]

  34. Alan Millar:

    When we had 3000 ppm CO2 in the atmosphere was that irreversible?

    Hmmm let me think!


    [Response: Try reading too. The definition of ‘irreversible’ above is linked to a time scale of 1000 years or so. Since I’m pretty sure the last time 3000 ppm happened was much longer ago than that, it’s hardly relevant. Unless you happen to have some new source of CO2 data with better than 1000 year resolution back in the Cretaceous which show changes much faster than that? …. Didn’t think so. – gavin]

  35. Gareth:

    There’s a full review of The Long Thaw here, part of an effort to assemble a reasonably complete set of reviews of current and future climate-relevant books (with thanks to Bryan Walker, who is doing most of the spadework).

  36. Chris McGrath:

    When we talk about climate change from burning fossil fuels we often forget to mention its ugly step-sister, ocean acidification.

    One consequence of the oceans acting as a sink for CO2 is that ocean acidification will last for similar timeframes as climate change:

  37. Jim Norvell:

    If it was easy to reduce our use of carbon energy, we would have already done it. Now if any of you think that we will be able to generate the needed energy in the next 50 years without carbon fuels or even moderately reduce them, then I have a some water front property in Colorado that I would like to sell. We cannot even agree on a new power grid to bring solar electric power from the Mojave to LA. If what you believe is in respect to AGW is true, then we truly are on the road to perdition and this 1k year prediction may well come true but we are not going to do anything to stop it. I am just going to enjoy my ride out.

    Jim N

  38. Durbrow:

    How can we learn about possible methods to withdraw CO2 from the atmosphere. Can someone refer me to a reliable post or website on methods to take out the CO2? Thanks!

    [Response: Look for papers by David Keith and Kurt House. David]

  39. Jerry Toman:


    Most of what you said is correct, except that, by geo-engineering, we can alter the earth’s energy budget causing cooling to occur, especially over arctic regions.

    We are only encouraging warming in this area by our jet traffic during the winter months, which traps heat. Air traffic should be suspended at high latitudes (>45) through March. After this, it should be increased to create cirrus clouds which reflect the initial low-angle solar radiation back into space and delay the onset of the arctic spring. Sulfur could be added to the fuel to increase reflectivity of the clouds formed. During the summer, ships burning high-sulfur fuel could be added to the mix.

    Via deployment of the Atmospheric Vortex Engine ( on a large scale, we can eliminate 90% fossil fuel use for electricity generation within ten years, and thereby take care of the CO2 emissions problem, and possibly, increase the earth’s albedo at the same time.

    CO2 sequestration can be achieved via increasing crop production (, followed by char production from the biomass and burial of same.

  40. Danny Bloom:

    Jesse Ausubell at Rockefeller University said it best in 1989, and I repeat his call in my Graduation Speech to the Class of 2099 here:

    “We must loosen the noose around coal.”

    Dr Ausubel said that, remember, in 1989, in a published paper. It is now 2009. The unstoppable is getting more and more unstoppable. At what point, do we act? By 2099 it might be too late. Stop all car and truck traffic now? Now? Or just go on with business as usual, screw the future of the human species…..

  41. Ray Ladbury:

    Jim Norvell says, “I am just going to enjoy my ride out.”

    Anything to justify selfishness and inaction, huh, Jim? Your children must be so proud.

  42. Ray Ladbury:

    Alan Millar says “When we had 3000 ppm CO2 in the atmosphere was that irreversible?

    Hmmm let me think!”

    Not bloody likely.

  43. Hank Roberts:

    > We cannot even agree on a new power grid to bring solar
    > electric power from the Mojave to LA

    Sure you can: simply choose not to use it as an excuse to cut a big road swath through Joshua Tree. Put it along occupied corridors.
    Simple — place it so distributed small generation can tie into it, rather than placing it where _only_ the one big utility generator can connect at one end and the other, and the rest in Joshua Tree.

    That’s not what the new grid is supposed to be about, is it?

  44. Marcus:

    #9,10,20: Geoff Beacon: The absolute methane sink increases with increasing concentration, so no, we aren’t doomed by increasing methane emissions. Reasoning:

    If we could magically hold the OH level in the atmosphere constant, then methane lifetime would be constant, so the sink would be directly proportional to the concentration. d[CH4]/dt = [OH]*[CH4]

    Of course, OH isn’t a constant, and yes, with increasing methane emissions the OH level will likely drop, so methane lifetime will increase somewhat, but if we reduce emissions the OH level will come back up. If we were to cut all anthropogenic emissions of CH4, VOCs, NOx, etc. to zero, we’d probably return to near preindustrial OH levels fairly quickly – within a few years, would be my guess, mostly controlled by the time it takes for the longest lived OH sinks to return to preindustrial levels as well.

  45. Jim Norvell:

    Ray, Hanson gives us 4 years (

    The writer of this thread says that we are doomed for 1k years. What is your solution?

    Jim N

  46. jyyh:

    Every now and then people keep telling there’s been 3000 ppm CO2 in the atmosphere before, and that it hasn’t been a problem to the life on earth. I’d advise these people to take a look of the vegetation during the time, do you see many crops growing? Are we heading to the fern world of dinosaurs? I’d like to think redwoods and such large conifers should be promoted everywhere they can grow. The needles are more acidic than leaves, making the soil beneath those hard to cultivate, maybe there would be a place to put the olivine? Difficult issues for us AND the future generations.

    ReCaptcha Arrangements first, and I tend to agree.

  47. Rick Brown:

    re #45 Jim Norvell

    Maybe you missed it, but this has been clarified here before. Hansen says that Obama has the four-year term he has been elected to serve. That’s not the same thing as giving “us” four years.

  48. truth:

    This is how Susan Solomon’s words were reported in The Herald:

    Ms Solomon said: ‘Climate change is slow, but it is unstoppable – all the more reason to act quickly, so the long-term situation does not get even worse’.

  49. Edward Greisch:

    The good news is: Factory built small nuclear power plants are here to replace fossil fuel power plants.
    Downloaded from:
    For Immediate Release
    Press Contact: Claire Gimble

    Hyperion Power Generation Lands Initial Set of Customers for the HPM Small, Safe, Transportable Nuclear Power Reactor
    LOS ALAMOS, N.M., August 12, 2008 — Hyperion Power Generation’s CEO, John R. “Grizz” Deal, announced today that the company has received its first Letter of Intent to purchase the Hyperion Power Module ™ (HPM), a small, compact, transportable, nuclear power reactor.
    The intention to purchase up to six units for various projects, at approximately $25 million each, was placed by TES Group, an investment company focusing on the energy sector in Central Eastern Europe. If successful, they could potentially be in the market for up to 50 HPMs. Each power module provides 27 megawatts of electricity when connected to a steam turbine, enough to provide electricity for 20,000 average-size American-style homes or the industrial equivalent.
    “The Hyperion Power Module was originally conceived to provide clean, affordable power for remote industrial applications such as oil sands operations,” said Deal. “Yet, the initial enthusiasm has been from those needing reliable electricity for communities. The big question for the 21st century is, ‘how do we provide safe energy to those who need it, indeed those developing nations who demand it, without contributing to climate change?’ Today’s safer, proliferation-resistant nuclear power technology is the answer, but it’s not feasible for every community to be tied to a large nuclear power plant. Some communities, those that need power for just the most basic humanitarian infrastructure, such as clean water production for household use and irrigation, are too remote for conventional nuclear power. This is where the Hyperion Power Module, a safe, secure, transportable power generator can help.”
    Conceived at Los Alamos National Laboratory, the Hyperion Power Module intellectual property portfolio has been licensed to Hyperion Power Generation for commercialization under the laboratory’s technology transfer program. Inherently safe and proliferation-resistant, the HPM utilizes the energy of low-enriched uranium fuel in a technology unlike any other currently in use or in development. Approximately 4,000 units of the same design will be produced, sealed and shipped from company manufacturing sites.

    27 megawatts divided by $25 Million = $0.9259 per installed watt.
    I think that includes fuel for 5 or 10 years, which is inside the core. It is a good deal for a small power plant. Electricity from this mini-nuke costs 5 to 6 cents per kilowatt hour. It shouldn’t be expected to produce electricity a cheaply as a 1000 MWe power plant.

  50. Jonas:

    Interesting Article…

    But, I’m a bit confused about reading this article on CO2 and it’s
    warming effect noted in Antartic ice core samples.

    Can someone please explain …?

    [Response: What’s to explain? The climate affects the carbon cycle – over ice age timescales it seems to be mainly through ocean processes (solubility, production, stratification) which takes time to work through. CO2 is still a greenhouse gas, and so the combination is an amplification of the cycles which are driven by orbital wobbles. None of this is controversial. – gavin]