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Climate Hustle

Changing the Direction of the Climate

Posted on 1 December 2011 by dana1981, Andy Skuce

As Andy recently discussed, the International Energy Agency (IEA) has published the World Energy Outlook 2011 (WEO11), which incorporates the most recent data on global energy trends and policies, and investigates the economic and environmental consequences of three scenarios over the 2010 to 2035 time period:

  • The New Policies Scenario. This is used as a reference case. It assumes that governments will follow through on the (non-binding) pledges that they have made to reduce emissions and deploy renewable energy sources.

  • The 450 Scenario. This is an outcome-driven scenario, which lays out an energy pathway designed to limit the long-term concentration of greenhouse gasses to 450 ppm CO2 equivalent. Achieving this would provide a 50% chance of limiting global temperature increases to 2°C. Some climatologists, such as James Hansen, argue that a more aggressive 350 ppm target is required to avoid the possibility of “seeding irreversible catastrophic effects”.

  • The Current Policies Scenario.  This projection models a future in which only those climate and energy policies actually adopted in mid-2011 are incorporated.

The IEA focuses on CO2 emissions from energy production, as we'll see below.  Their 450 Scenario proposes to keep CO2 equivalent (including all atmospheric greenhouse gases) concentrations in the vicinity of 450 ppm by very quickly reducing both non-fossil fuel CO2 emissions (i.e. reducing deforestation) and non-CO2 greenhouse gas emissions (i.e. methane), such that their emissions in 2020 are lower than today.  However, the main focus of the report is on fossil fuel CO2 emissions.

IEA vs. IPCC Scenarios

There's some good news and some bad news in the IEA scenarios.  The good news is that the IEA is more optimistic regarding future greenhouse gas emissions than the IPCC.  Figure 1 compares cumulative emissions, the corresponding atmospheric CO2 concentration, and the resulting global surface warming at equilibrium (assuming a climate sensitivity of 3°C for doubled CO2) from the IEA and some of the IPCC SRES scenarios (for morre details on the IPCC SRES scenarios, see here).

iea vs ipcc data

Figure 1: Cumulative human fossil fuel CO2 emissions since 2001, resulting atmospheric CO2 concentration, and expected equilibrium surface warming for some IPCC SRES scenarios (solid lines) and the IEA scenarios (dashed lines).  Horizontal reference lines are provided for 1 trillion tons of cumulative CO2 emissions, 450 ppmv CO2, and 2°C warming.

The IEA New scenario, which only requires that governments follow through on current pledges to reduce greenhouse gas emissions, is on par with IPCC scenario B2, which is expected to result in approximately 3°C warming above pre-industrial levels by 2100.  The bad news is that this better than business-as-usual scenario will commit us to more than the 2°C 'danger limit' of global warming by 2035 (note this is eventual warming at equilibrium, which takes several decades, not warming by 2035).

How to Avoid Dangerous Warming

Figure 2 illustrates the annual fossil fuel CO2 emissions in the IPCC SRES and IEA emissions scenarios.

annual emissions

Figure 2: Annual CO2 emissions from fossil fuels for some IPCC SRES scenarios (solid lines) and the IEA scenarios (dashed lines).

All of the IPCC emissions scenarios, and the IEA Current and New scenarios depict fossil fuel CO2 emissions continuing to rise beyond 2035.  In order to keep atmospheric CO2 concentrations below 450 ppm, the IEA creates a scenario in which those emissions peak in approximately 2018.  The IEA provides a possible blueprint to achieve these emissions reductions in Figure 3.

Figure 3: World energy-related CO2 emissions abatement in the IEA 450 Scenario relative to the IEA New Policies Scenario.

The IEA suggests that nearly 50% of the emissions reductions should come from increased energy efficiency, and approximately 15% each from increased deployment of renewable energy technologies and carbon capture and storage (CCS) by 2035. 

IEA Optimism

The IEA is also optimistic in that their 450 scenario allows for 984 billion tons of CO2 emissions from fossil fuels by 2035, and approximately 1.2 trillion tons by 2050.  The Australian Climate Commission in its report The Critical Decade concluded that to have a 75% chance of avoiding 2°C warming, we only have a budget of 1 trillion tons of CO2 emissions between 2000 and 2050 (the IEA aims for 50% probability of limiting warming to 2°C). 

Since the amount of warming caused by a given CO2 increase depends on the climate sensitivity, which has a fairly large range of uncertainty, it's possible that the IEA more optimistic emissions allowance will suffice in limiting global warming below the 'danger limit', although it reduces the probability of success.  The IEA also belives that current committments are sufficient to keep us on track with IPCC SRES scenario B2, even though so far this century we're on pace for the much higher A2 scenario (Figure 4).

iea emissions data

Figure 4: IEA emissions data through 2010 compared to the IPCC SRES emissions scenarios

We hope the IEA's optimism is warranted.

Path Changing Challenges

The WEO11 report notes some major challenges in achieving its 450 scenario:

Four-fifths of the total energy-related CO2 emissions permissible by 2035 in the 450 Scenario are already “locked-in” by our existing capital stock (power plants, buildings, factories, etc.). If stringent new action is not forthcoming by 2017, the energy-related infrastructure then in place will generate all the CO2 emissions allowed in the 450 Scenario up to 2035, leaving no room for additional power plants, factories and other infrastructure unless they are zero-carbon, which would be extremely costly. 

In short, the IEA arrives at the same conclusion as The Critical Decade: because of the long lifespans of power plants, we are very quickly running out of time to take sufficient action to sufficiently reduce our CO2 emissions.

The report also notes that we're not helping the economy by delaying action - quite the contrary, as Skeptical Science has documented:

Delaying action is a false economy: for every $1 of investment avoided in the power sector before 2020 an additional $4.3 would need to be spent after 2020 to compensate for the increased emissions.

The Time to Change Direction is Now

The key quote from the WEO11 Executive Summary is:

If we don’t change direction soon, we’ll end up where we’re heading

As Figures 1 through 3 show, where we're headed is upward towards ever-more dangerous global warming, and where we need to go is downwards towards low fossil fuel consumption, low CO2 emissions, and stable atmospheric CO2 concentrations.  In order to achieve this change in direction, we must take serious action to reduce our emissions immediately, because we're on track to lock in dangerous warming by 2017, and the IEA 450 scenario requires that CO2 emissions peak in 2018.  Achieving an emissions peak within ~5 years requires that we begin enacting serious climate policy immediately.

The WEO11 foreward, written by Executive Director Maria van der Hoeven, sums up the situation very well:

The starkest decisions are those which must be taken without delay. I end by highlighting one area squarely in this category: the energy decisions necessary to contain the rise in the average global temperature to 2° Celsius. We read here of the way carbon emissions are already “locked-in” because of the nature of the plant and equipment which we continue to build. If we do not change course, by 2015 over 90% of the permissible energy sector emissions to 2035 will already be locked in. By 2017, 100%. We can still act in time to preserve a plausible path to a sustainable energy future; but each year the necessary measures get progressively tougher and viciously more expensive. So, let’s not wait any longer!

Realistically speaking, we're probably not going to be able to avoid the 2°C danger limit.  But it's worth remembering that the danger limit is not a hard and fast threshold (though some, like James Hansen, believe it's far too high of a target).  Even if we miss the target, it's critical that we exceed it by as little as possible.  As Lonnie Thompson put it,

Sooner or later, we will all deal with global warming. The only question is how much we will mitigate, adapt, and suffer.

The longer we wait to implement serious mitigation, the more adaption and suffering will result.  As van der Hoeven said, let's not wait any longer!

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Comments 1 to 37:

  1. One reason we may end up 'wait to implement serious mitigation' may be found in op-ed pieces like the one in our local paper this morning, titled "Of course, Canada ditched Kyoto commitments". The author, Michael Den Tandt writes as follows:
    "The skeptical science, for years confined to the scruffy margins by the International Panel on Climate Change and its supporters, took a huge leap forward with the discovery by no less than the CERN laboratories based in Switzerland-arguably the most prestigious scientific group in the world-that fluctuations in the sun's magnetic field have a very large, perhaps dominant effect on the earth's climate."
    He continues "the CERN findings are steadily trickling through the blogosphere, quietly altering the political discussion everywhere..."
    The only thing I can think he is referring to is the CERN work relating cosmic rays to cloud formation, but I get most of my climate science from this site.
    Hopefully, someone more familiar with the science than I am can stop this trickling before it drowns the discussion.
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  2. jimb - see our CERN rebuttal
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  3. Thanks
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  4. According to his website, "Michael Den Tandt is a national political columnist for Postmedia News, publisher of the National Post, Ottawa Citizen, Montreal Gazette, Calgary Herald, Vancouver Sun and Halifax Chronicle-Herald."

    Not a reputable scientific source.
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  5. The IEA is pipe dreaming if they think Emissions will peak and began to decline in 2017. I see emissions peaking in 2035 or 2040- when C02 will have passed 450ppm.

    At this point a 3 degree rise C is certainty- we can only hope we do not go beyond that.
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  6. I have to agree, while 450 ppm is technically feasible, we clearly don't have the political will to make it happen. But the IEA is just discussing how we could do it, if we had the will. Realistically I don't see how we'll avoid blowing past 2°C, which is a scary thought.
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  7. If CO2 levels are successfully reduced to pre-industrial levels, what responses in global temperature should be expected and how soon?

    If we are successful in reversing a rising temperature trendline, at what point do we want it to level out? Furthermore, at what point do we begin to worry about it getting too low?
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  8. Pirate, there is no chance of CO2 dropping too low. RealClimate has the story..
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  9. Pirate,
    No-one is suggesting that it is possible to return to pre-industrial levels. As discussed above, we will be lucky if we can hold levels under 450. How can you imagine we could reduce to 180? If we can ever get the amount of CO2 to level out (likely to be above 450) then we can start to consider what would be a good level to end at. Now we need to decide to begin to reduce the amount of pollution we put in the atmosphere.

    Reducing the amount in the atmosphere is very difficult because when you reduce the atmospehric amount, more CO2 comes out of the ocean in response. Have you really not considered this before?
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    [dana1981] pre-industrial is 280, not 180ppm.  But you're correct that there's virtually nil chance of us getting anywhere close to that, unless we invent some technology to remove massive quantities of CO2 from the atmosphere, or something.

    The question is not warming or cooling, it's how much more warming.

  10. Pirate,

    Lets first start by sequestering the 337 billion tons of carbon (and rising) released by the burning of fossil fuels then we can start worrying about the impact on climate?
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  11. Pirate,

    As we had been discussing offline (the conversation, once again, seems to have gone into a deep coma), there is no place for the CO2 to go once it has been extracted from the ground. It is already saturating the atmosphere and oceans. It took hundreds of millions of years for nature to sequester it underground through fossilization. There is no mechanism that I know of that will put a dent in the atmospheric CO2 levels. Perhaps an ocean expert here on the site knows of some such mechanism.

    I performed a "back of the envelope" calculation recently, under the presumption that we could somehow plant giant sequoia redwoods on any arable/agricultural land we could find (which isn't possible, of course, since those trees require their own very specific environment to grow, and one that is itself greatly threatened by global warming) and that these redwood forests would absorb the 337 Gt of carbon we have released through the burning of fossil fuels, by converting it into bio-matter.

    Under this premise, we would need to plant, today, redwood forests on at least 75% of all arable/agricultural land, and to allow them to grow for 100 years, before they successfully drew enough carbon (337 Gt) from the system to lower atmospheric CO2 levels back to the pre-industrial age.

    Of course, this does not allow for the fact that replacing existing forests with redwood forests is less of a net change.

    It also implies that all of humanity must move off of such land to live in high mountains, deserts and such. Worse than that, with only 25% of the agricultural land available after starting the "great carbon absorption" forests, we'll only be able to feed 25% of the 7 billion people currently alive.

    Of course all of this is just a fantasy, but one that serves to dramatically demonstrate exactly how much CO2 we have added to the atmosphere, and how absurd it is to think that we can somehow remove it.

    The genie is out of the bottle. It's just a question of how big we let the genie get before shackling him.
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  12. Just how much do we know about how long Co2 remains in the atmosphere? I have seen sources that say 100 years,and others that say 1000 years.Is there that much uncertainty?Either way,I think that this is an element of risk that most people do not fully appreciate.They probably have the idea that if all of the worst case scenarios start to occur,then it's just a matter of turning on a dime,and going green...problem solved! Right?
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  13. I dont think you can talk about an optimuum level of CO2. The trick is not to change it too fast. Repeating the mantra - its the rate of change that matters.
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  14. tmac57,

    I'm very curious about that topic (how long CO2 remains in the atmosphere) and need to do some research, because I'm not really sure where it is going to go, and how it is going to get there.

    Current atmospheric CO2 can't go into the ocean, because that is already becoming saturated, is already taking up as much of current and past emissions as it can, and will hold less and less CO2 as it warms. Eventually, the oceans may transition to a source rather than a sink for CO2.

    Current atmospheric CO2 can for a while go into plant matter but only for as long and as far as vegetation can grow and expand. If things get bad enough and deserts start to expand, droughts increase in frequency and strength, the Amazon transitions to savanna... that's another source of carbon rather than a sink.

    The only real way that I've seen to draw down current atmospheric CO2 from current levels comes from the biological pump and ocean circulation covered in this post on ocean acidifcation. But to do that, the ocean has to shed its CO2 in that fashion just to begin absorbing atmospheric CO2, to shed that to draw temperatures down to be able to hold more CO2 itself.

    It looks to me like 100 years is a very, very, very optimistic figure. It looks to me like a number on the order of thousands of years is far more likely.

    Does anyone have any references that point to a better answer?
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  15. Sphaerica,

    I'm not sure that this is relevent however AFAIK(and that is not very much) the long term answer (weathering of silicate rocks) is geological in process and time scale and according to this paper the ocean sequestration of CO2 is less effective than weathering of terrestial silicate rocks.
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  16. @12, tmac57:

    It's a distribution of times, rather than just a number:

    Carbon is forever, Nature, 2008
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  17. Spaerica,oneiota,and Chemware-Thanks for the Information.The Nature article said more about this than anything else that I have read on the subject...pretty unnerving,I must say.
    I find it rather extraordinary that this one aspect hasn't gotten more attention in stories of AGW.If the general public is not aware of the very long timelines that we could be stuck with the excess Co2,and all the concomitant problems that it causes,they might be too sanguine about it,thinking that our technology can easily overcome it in short order.
    This line from the Nature article really struck me: "If civilization was able to develop ways of scrubbing CO2 out of the atmosphere," Tyrrell says, "it's possible you could reverse this CO2 hangover."
    Wouldn't it be ironic if we had to end up using as much energy to 'scrub' out the Co2 from our atmosphere,as it took burning fossil fuels,to put it there?
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  18. tmac57 - "Just how much do we know about how long Co2 remains in the atmosphere? I have seen sources that say 100 years,and others that say 1000 years. Is there that much uncertainty?"

    Archer 2005 represents some fairly recent research on this topic. He models ocean sequestration, oceanic temperature feedback, rock weathering, etc.

    "...we expect that 17–33% of the fossil fuel carbon will still reside in the atmosphere 1 kyr from now, decreasing to 10–15% at 10 kyr, and 7% at 100 kyr. The mean lifetime of fossil fuel CO2 is about 30–35 kyr"

    The numbers following include modeled ocean thermal feedback (+), CaCO3 weathering (-), and silicate weathering (-) influences:

    First case - a 300gT slug (instant release) of carbon (what we've released so far), peak is > 350ppm (we're well above that now...):

    1kY: 16.8% (~315ppm)
    10kY: 9.8%
    100kY: 6.7%
    Mean lifetime kY: 34.7

    Worst case - 5000gT of carbon, burning all buried fossil fuels including all coal, peak for that slug is ~1700ppm:

    1kY: 32.9% (~525ppm)
    10kY: 15.1%
    100kY: 6.7%
    Mean lifetime kY: 36.1

    There are some fast adjustments, mostly soil sequestration and oceanic acidification - those have a half-life of ~40 years. But once those reach equilibrium we're down to longer term geologic sequestration - and that's very slow.

    "Humankind has already released about 300 Gton C from fossil fuels and deforestation, and the IPCC business-as-usual scenario (IS92a) projects about 1600 Gton of carbon released from a combination of fossil fuels and terrestrial fluxes, with emissions beyond 2100 unspecified."

    We're going to have to deal with the effects of our actions for quite some time to come.
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  19. [DB] - Just saw your moderation input, I'll have to look at those... not happy data, I have to say.
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    [DB] Conclusions of Archer 2009 (linked earlier):

    Nowhere in these model results or in the published literature is there any reason to conclude that the effects of CO2 release will be substantially confined to just a few centuries.

    In contrast, generally accepted modern understanding of the global carbon cycle indicates that climate effects ofCO2 releases to the atmosphere will persist for tens, if not hundreds, of thousands of years into the future.

    Relevant Graphics:

    Click to enlarge

    Click to enlarge

  20. tmac57 @17,

    Wouldn't it be ironic if we had to end up using as much energy to 'scrub' out the Co2 from our atmosphere,as it took burning fossil fuels,to put it there?

    I agree, reasonable balance of things means that the reversing of the reaction of burning C requires as much energy as was released multiplied by the efficiency of the reversal process. Natural processes are inefficient by far (i.e. photosynthesis is only at some 10% max, maybe even less I don't know) so forget about any help from nature to do that. That is confirmed by the studies above.

    So it's not just ironic but simply obvious that to "fix" that imbalance we need to reverse the energy flow. But there is some good news: human ingenuity cannot be included in those models. Who knows, in some 100y someone (a modern-day "divine savior") may invent an "artificial photosynthesis" working at close to 100% efficiency with which our descendents will start pumping extracted C directly into the empty holes (mines) we left to them as our heritage. And there is plenty of sun energy to do that. Of course it's SF but at least some hope that AGW is reversible in theory and humanity does not need to be cursed for 10-100ky.
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  21. Thanks to all DB and others for the resources.That's why I really enjoy SkS,everyone is so willing to help with answers and link to good educational material.
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  22. tmac,

    Sadly, it would be lucky if it only takes as much energy to scrub the atmosphere as we got from burning fossil fuels. The laws of thermodynamics rather almost require that it will take more energy (rather than merely the same amount) to reverse the process.

    Remember, in a nutshell the laws of thermodynamics say:
    • You can't win
    • You can't break even unless it is very, very cold
    • It never gets that cold
    • You can't quit the game.
    Getting the atmosphere back to where it was but at no net expense is trying to break even. You can only do that if you return to a snowball earth, and you can't do that.
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  23. What I find hard to understand is why no political party (here in New Zealand and elsewhere) is prepared to advocate Jim Hansen's Tax and Dividend. Besides being likely to be very effective in reducing the output of Carbon dioxide, it seems like a real vote winner. Who could resist 'cocking a snook' at 'the man' and receiving a nice addition to one's credit card each month. Anybody out there understand what is happening.
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  24. Nice comment Sphaerica. Beautiful rendition of the laws of thermodynamics. Fortunately we have a source of energy that could reverse the trend - namely the sun. If we allowed the forests to regenerate, and the biomass of the seas to recover we would store up a lot of Carbon dioxide. Sea level rise may also help as corals grow up to the new low tide level. Calcium carbonate is a tad over 60% carbon dioxide. We won't do the first two so the only thing to do is to sit down, assume the prenatal position and kiss you know what goodby.
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  25. By the time the people who are willingly ignorant on the subject of Climate Change are forced, by reality, to change their tune, we will in the 3C+ committed range. That seems inevitable at this point, even though there is still time on the clock, and responsible people MUST push for change against all odds (in my humble opinion...).

    So we are left with mitigation the effects, and technological fixes.

    In the fixes area, this article caught my attention:
    and it uses solar power to do it!
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    [DB] Fixed link.

  26. Sphaerica #22. From what I've read, it doesn't take as much energy to capture CO2 as the energy produced releasing that CO2. For example, see here

    And if it was the case, CO2 scrubbers on power plant stacks wouldn't have been developed. But unless we have significantly greater non-carbon based energy production, we're not going to make a dent on CO2 in the atmosphere. Nor do I see the political will to make any significant changes to business as usual. China, for example, may have the largest capacity of electrical generation by wind turbines, but it is also the largest user of coal - and therefore the largest producer of CO2. But at least they're looking at alternatives such as the Liquid Fluoride Thorium reactors (as well as a few other nations).

    What's needed is a Manhattan style project to develop fusion reactors.

    Long term the planet will survive - the planet will warm, the human infestation will suffer massive dieback, and subsequently, maybe millions of years time, some other intelligent life form may evolve. But that's not a very anthropologic friendly perspective is it?
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  27. actually thoughtful #25
    Corrected the link:
    and it uses solar power to do it!
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  28. PhilMorris-"What's needed is a Manhattan style project to develop fusion reactors. "
    Been done...just look up ;)
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  29. PhilMorris - thank you. I like to think of myself as technologically literate, but occasionally reality intrudes....
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  30. 24, william,

    I'm afraid forests won't make a dent in the problem. We've burned 337 Gt of carbon since 1751. I did some rough estimates, and it seems that planting giant sequoia redwoods would require using 75% of the arable land on the planet to allow those trees to grow large enough that in 100 years they absorbed all of the carbon released to date, and that assumes that we stop now, and that humanity abandons all of that land for use for living space and food production.

    At the same time, climate change is going to cause deserts to expand and so to shrink the amount of arable land available.

    I wouldn't count on natural sinks -- corals or trees -- to make any sort of dent in the problem.
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  31. PhilMorris @ 26:

    I'm going to guess that there is a huge difference between scrubbing CO2 from from a highly-concentrated source of emission ad storing it as CO2, and removing it as a trace element from the atmosphere-at-large. If removing it as a trace element involves splitting CO2 back into C and O2, then the thermodynamics is as Sphaerica states.
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  32. 26, PhilMorris,

    I was probably a little too quick, flip and shooting from the hip in my post, although I would note that (a) your linked paper appears to be old, or at best references 1999 material and (b) most efforts are concerned with breaking even from some point forward (i.e. capture as much as you release), not scrubbing back what we've already let lose.

    Still, yes, maybe with enough, efficient renewable energy sources we could solve the problem. The sun should burn for long enough. The question is probably more of "can we draw it down quickly enough to keep civilization thriving long enough to develop and implement the technology on a large enough scale to have the necessary impact... or are we all just buzzard meat."
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  33. If we're talking about the carbon 'cycle' and referring to photosynthesis and the like, we're overlooking what burning fossil materials actually does.

    It doesn't disrupt the biological carbon cycle, it violates the geological carbon cycle. If we want to suck out CO2 released by internal combustion motors alone, then one year's worth equates to about 93 million years' worth of fossil deposition. Growing trees won't do it.

    What we need is a way to speed up geological weathering processes. So far, I've only come up with a process as crude and clumsy as our fossil fuel extraction processes.

    Blow things up. It's sort of equivalent in that we've been knocking off mountains and quarrying huge holes in the ground to get at fossils. We'll just need to do much the same thing with mountains and holes in different rock formations. The only saving grace is that the necessary rocks are abundant and easily accessible.

    The mental image I have is that instead of using small planes as crop dusters, those same small planes will become one of the prime targets for developing a carbon neutral fuel. Because we'll be needing to fly round the clock dusting operations over selected reef systems and their associated coasts to ward off the very worst ravages of acidification and species loss in just a few areas. We won't be able to save them all.
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  34. Does the IEA report CO2 levels with just CO2, or as a net CO2 amount that includes CO2 equivalents as well? If not, then methane and N2O are also important considerations for action in the short term. Perhaps, if we start with ways to reduce these GHG's we will have more success at delaying the necessity of mitigation efforts. My concern is a sudden surge of methane and CO2 from boreal stocks and offshore environments as sea and tundra temperatures continue to rise. Have these been included in their analysis?
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  35. On the subject of reversing CO2 emissions, one thought I sometimes fixate on is this:

    If we put aerosols up into the atmosphere they might shield us from some of the warming for a period. We also need to pull CO2 out of the atmosphere which ultimately needs to involve some aspect of the Calcium Carbonate chemistry cycle. And this needs a power source to fuel the reversal of chemical reactions.

    So... Could we create a nano-something that we inject into the atmosphere. Its short term impact is to act as an aerosol and have a cooling effect. But its other effect is to use solar anergy to drive chemical reactions in the atmosphere, on the surface of the nano-particle, that grab some CO2 and push it down into the surface carbon cycle, ultimately to be sequestered. If we just keep pumping this nano-something-or-other up there, ultimately we achieve the balance we need.

    I leave it as a simple exercise for all you chemistry typpes to work out the technicalities.
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  36. TMac57

    How long does CO2 last in the atmosphere. Simple answer. Some doesn't last very long, some lasts a bit longer, some lasts longer still, some lasts even longer.

    Another way of looking at it is that the main place CO2 can go is into the oceans. So CO2 can go into the surface layers of the oceans fairly quickly - decades. Then how fast it can go into the oceans more than that depends on how quickly the surface layers of the oceans mix with the deep oceans - centuries, up to a few millenia. Once the atmosphere and oceans, with all their mixing, are in balance after a millenium or two things stay static until additional processes kick in. Mainly carbonates dropping out ofthe ocean to the sea floor to ultimately be sequestered in subduction zones. And also a slower pump based on the formation of Carbonic Acid in the atmosphere from the reaction between CO2 and water slowly rains out of the atmosphere, reacts with rocks and adds to the carbonate cycle in the oceans. This has a typical time constant of around 100,000 years.

    So we are looking at processes that remove some CO2 on decade timescales, some on century to millenial scales and some on scales of 100's of 1000's of years.

    If H Sapiens stops emitting CO2 within a century, 500,000 years from now you will barely even know we were here. Apart from the geological evidence.
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  37. re posts 1-4- a bit late, but the local paper printed two 'letters to the editor' pointing out that CERN did not in fact say what the author of the op-ed piece said it did (and thanks for the link) Unfortunately I expect that a lot more people read the op-ed piece than the letters.
    Also in the news was the story that Canada was withdrawing from Kyoto, something that had been rumoured for some time, but confirmed today. This seems to be continuing a pattern.
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