It doesn't sound like anyone took a close look at David's graph. It shows supposed projections for CO2 levels to reach either 950 ppm or 450 ppm *by 2007*. Then it compares the Mauna Loa data to these projections, and implies that somehow modelers got things wrong.
But of course no one has predicted that CO2 levels would rise that fast. We might reach 450 ppm somewhere in the middle of this century, and 950 ppm by 2100 or later, if we stick to business-as-usual. David--did you make a mistake in labeling the axes on your graph? It seems you must have--and that your graph doesn't support your conclusions. --Mason (p.s. I'm the one who wrote the article that Ken posted at the start of this thread.) On Nov 23, 7:31 pm, "David Schnare" <[EMAIL PROTECTED]> wrote: > Ken, John, et al: > > My confidence in our understanding of the carbon cycle has reached what I > hope is a nadir. Attached is a chart of Mona Loa CO2 data and actual CO2 > emissions data. They do not reflect a 100 year dwell time in the > atmosphere. The literature on CO2 half-life suggests a 7.5 year half-life > with the range from about 5 to 15 years. That range is a better explanation > of the actual CO2 data than the modeled estimates (by a wide margin). > > Thus, one wonders, what are the GCM modelers assuming, and how close to > reality is that? > > David Schnare > Center for Environmental Stewardship > > On Sun, Nov 23, 2008 at 6:03 AM, John Nissen <[EMAIL PROTECTED]> wrote: > > > Hi Ken, > > > You are forgiven for breaking the rules, because you are not. What you > > have posted is extremely relevent - and is what started me off on taking > > geoengineering seriously - not the carbon capture but the aerosol cooling > > geoengineering. We need to understand the carbon cycle in order to > > appreciate the imperative for geoengineered cooling. > > > There is no alternative to geoengineered cooling in the short term, the > > awsome problem of saving the Arctic sea ice - which is ignored in this > > article. I know you appreciate this [1]. > > > When I read the IPCC report in 2007 about stabilisation at 2 degrees, I > > could not understand how they arrived at the "climate sensitivity", on which > > all their calculations seemed to be based. When I looked into it, their > > calculations seemed to use 140 years as the lifetime for CO2 - the half life > > for the 50% of CO2 which is not immediately absorbed. > > Your article does not explain that, as CO2 concentration increases in the > > atmosphere, the equilibrium concentration in the ocean and biomass > > increases. This explains the almost exactly 50% of CO2 which is immediately > > absorbed. > > > It is the lifetime of the remaining 50% which is of concern. If we halted > > all CO2 emissions overnight, what would the effect be? IPCC gave a mean > > estimate of around 140 years. Yet I found papers saying that this > > lifetime was thousands of years - one gave 32,000 years as an estimate. Who > > was right? I suspected the longer time could be correct, and your research > > confirms that. So emissions reduction, however severe, would not halt > > global warming. > > > Your article suggests the answer is geoengineering to remove carbon. But > > we do not have the time. We have to apply cooling techniques, of which only > > the stratospheric aerosols and marine cloud brightening techniques offer > > high feasibility of sufficient scaleability over the few seasons to save > > the Arctic sea ice from disappearing over the next few years. > > > Thus your article is highly relevent to geoengineering. > > > Cheers from Chiswick, > > > John > > > [1] You gave a telling postscript to a recent posting of yours (re > > Worldwatch Book): > > > PS. By the way, given that changes in CO2 emissions will not significantly > > affect temperatures over the next decade or two in any plausible scenario, > > it is hard to image how anything other than climate engineering can > > significantly reduce climate risk over this time period (perhaps there are > > adaptive strategies that could reduce this risk, but it is hard to see how > > those would apply to sea ice, ice sheets, arctic ecosystems, and > > permafrost). > > > ----- Original Message ----- > > *From:* Ken Caldeira <[EMAIL PROTECTED]> > > *To:* geoengineering <[email protected]> > > *Sent:* Saturday, November 22, 2008 3:08 AM > > *Subject:* [geo] Carbon is forever (Nature online news story) > > > NOTE: I AM BREAKING THE RULE ABOUT POSTING GENERAL CLIMATE/CARBON POSTS TO > > THIS GROUP. (BAD, BAD, BAD) > > >http://www.nature.com/climate/2008/0812/full/climate.2008.122.html > > > News Feature > > > Nature Reports Climate Change > > Published online: 20 November 2008 | doi:10.1038/climate.2008.122 > > Carbon is forever > > > *Carbon dioxide emissions and their associated warming could linger for > > millennia, according to some climate scientists. Mason Inman looks at why > > the fallout from burning fossil fuels could last far longer than expected. > > * > > [image: Carbon is forever] > > > Distant future: our continued use of fossil fuels could leave a CO2legacy > > that lasts millennia, says climatologist David Archer > > > 123RF.COM/PAUL <http://123rf.com/PAUL> MOORE > > > After our fossil fuel blow-out, how long will the CO2 hangover last? And > > what about the global fever that comes along with it? These sound like > > simple questions, but the answers are complex — and not well understood or > > appreciated outside a small group of climate scientists. Popular books on > > climate change — even those written by scientists — if they mention the > > lifetime of CO2 at all, typically say it lasts "a century or > > more"1<http://www.nature.com/climate/2008/0812/full/climate.2008.122.html#B1>or > > "more than a hundred years". > > > "That's complete nonsense," says Ken Caldeira of the Carnegie Institution > > for Science in Stanford, California. It doesn't help that the summaries in > > the Intergovernmental Panel on Climate Change (IPCC) reports have confused > > the issue, allege Caldeira and colleagues in an upcoming paper in *Annual > > Reviews of Earth and Planetary > > Sciences*2<http://www.nature.com/climate/2008/0812/full/climate.2008.122.html#B2>. > > Now he and a few other climate scientists are trying to spread the word that > > human-generated CO2, and the warming it brings, will linger far into the > > future — unless we take heroic measures to pull the gas out of the air. > > > University of Chicago oceanographer David Archer, who led the study with > > Caldeira and others, is credited with doing more than anyone to show how > > long CO2 from fossil fuels will last in the atmosphere. As he puts it in > > his new book *The Long Thaw*, "The lifetime of fossil fuel CO2 in the > > atmosphere is a few centuries, plus 25 percent that lasts essentially > > forever. The next time you fill your tank, reflect upon > > this"3<http://www.nature.com/climate/2008/0812/full/climate.2008.122.html#B3> > > . > > > "The climatic impacts of releasing fossil fuel CO2 to the atmosphere will > > last longer than Stonehenge," Archer writes. "Longer than time capsules, > > longer than nuclear waste, far longer than the age of human civilization so > > far." > > > The effects of carbon dioxide on the atmosphere drop off so slowly that > > unless we kick our "fossil fuel addiction", to use George W. Bush's phrase, > > we could force Earth out of its regular pattern of freezes and thaws that > > has lasted for more than a million years. "If the entire coal reserves were > > used," Archer writes, "then glaciation could be delayed for half a million > > years." > > Cloudy reports > > > "The longevity of CO2 in the atmosphere is probably the least well > > understood part of the global warming issue," says paleoclimatologist Peter > > Fawcett of the University of New Mexico. "And it's not because it isn't well > > documented in the IPCC report. It is, but it is buried under a lot of other > > material." > > > It doesn't help, though, that past reports from the UN panel of climate > > experts have made misleading statements about the lifetime of CO2, argue > > Archer, Caldeira and colleagues. The first assessment report, in 1990, said > > that CO2's lifetime is 50 to 200 years. The reports in 1995 and 2001 > > revised this down to 5 to 200 years. Because the oceans suck up huge amounts > > of the gas each year, the average CO2 molecule does spend about 5 years in > > the atmosphere. But the oceans also release much of that CO2 back to the > > air, such that man-made emissions keep the atmosphere's CO2 levels > > elevated for millennia. Even as CO2 levels drop, temperatures take longer > > to fall, according to recent studies. > > > "The climatic impacts of releasing fossil fuel CO2 to the atmosphere will > > last longer than Stonehenge, longer than time capsules, longer than nuclear > > waste, far longer than the age of human civilization so far." > > > David Archer > > > Earlier reports from the panel did include caveats such as "No single > > lifetime can be defined for CO2 because of the different rates of uptake > > by different removal processes." The IPCC's latest assessment, however, > > avoids the problems of earlier reports by including similar caveats while > > simply refusing to give a numeric estimate of the lifetime for carbon > > dioxide. Contributing author Richard Betts of the UK Met Office Hadley > > Centre says the panel made this change in recognition of the fact that "the > > lifetime estimates cited in previous reports had been potentially > > misleading, or at least open to misinterpretation." > > > Instead of pinning an absolute value on the atmospheric lifetime of CO2, > > the 2007 report describes its gradual dissipation over time, saying, "About > > 50% of a CO2 increase will be removed from the atmosphere within 30 years, > > and a further 30% will be removed within a few centuries. The remaining 20% > > may stay in the atmosphere for many thousands of years." But if cumulative > > emissions are high, the portion remaining in the atmosphere could be higher > > than this, models suggest. Overall, Caldeira argues, "the whole issue of our > > long-term commitment to climate change has not really ever been adequately > > addressed by the IPCC." > > > The lasting effects of CO2 also have big implications for energy policies, > > argues James Hansen, director of NASA's Goddard Institute of Space Studies. > > "Because of this long CO2 lifetime, we cannot solve the climate problem by > > slowing down emissions by 20% or 50% or even 80%. It does not matter much > > whether the CO2 is emitted this year, next year, or several years from > > now," he wrote in a letter this August. "Instead ... we must identify a > > portion of the fossil fuels that will be left in the ground, or > > ... > > read more » > > Reality in CO2 Assumptions.doc > 37KViewDownload --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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