Hi Gene,
I just add to Mike MacCracken's points that Venus should be a cold place if CO2 trapped only limited amount of heat, Venusian plenty of sulphur dioxide cooled what it could, while all the sunlight is being deflected by its extremely bright and thick white cloud cover. Please note that the features in the Venusian cloud cover are only visible with special narrowband filters that can pick up tiny hues out of that snowball-white planet. Therefore, there are a circulatory potential for the planetary system to respond in a runaway fashion. Due to the presense of carbon and large amount of water on Earth these things are not so inconceivable as the convections would become far stronger and move heat downwards in column where it cannot radiate easily out just like happens in boiling hot Venusian nights. Think alone the night time in Venus when there is no sunlight around. If too much carbon dioxide and vater vapour is above, there is not +25C saturation point. Whoever knows then what could happen if more and more of water turns up and appears as vapour than water. In Finland we do have saunas and you can pour many buckets of water on stove until all the air is virtually squeesed out and you breath steam and your skin starts burning. What I simply think would happen that the heat would be transported more and more rapidly down in the water, forcing dissolved gases out and eventually water that it would be just like a Finnish or Turkish sauna that one literally floats in steam. Whilst you can stay alive for a while in such a water vapour laden system (please note also that water vapour has high thermal inertia, heat retention per mass), one would die soon in such an environment for exhaustion and only few bacteria would remain active just like in the deep sea volcanic vents. But one could not survive longer than hours or a day sauna. When water comes more active part-taker, i.e. in case of Mars, there is a relative scarcity of both athmosphere and water, there is inherent lack of the liquous-gaseous thermal inertia which is present in both the Earth and Venus were they become over-heated. Thus I think the term Terminal Climate Change is a quite approppriate term how to describe the super-hot earth system (Stephen Hawkins or James Lovelock) as the other opposite alternative to snowball earth (a runaway global cooling) when all liquid water turns to solid. Kind regards, Albert Date: Fri, 12 Jun 2009 11:29:55 -0400 Subject: Re: [geo] Re: Back to Nature From: [email protected] To: [email protected]; [email protected]; [email protected]; [email protected] CC: [email protected] Dear Eugene—Your argument about the CO2 bands saturating was, as I understand it, one of the major two criticisms of Arrhenius when he first put forward the greenhouse gas hypothesis (the other was that the oceans had so much carbon there was no way that the atmospheric concentration could be increased as the ocean would take up virtually all of the emissions—some still believe this, but it was firmly proven wrong by Seuss and Revelle in the late 1950s when evidence made clear that the ocean could not be assumed to be well-mixed, but had a thin upper layer only slowly coupled to the deep ocean). It also took some time to get to the bottom of the criticism that you raise, but that happened and was concluded by the efforts of Manabe and others in the early 1960s who constructed a multi-layer radiative-convective model of the atmosphere, which made clear that thinking of the atmosphere as a single slab was simply wrong (for it to be considered as such, the layer would have to, for example, radiate upwards and downwards at the same temperature, and this is clearly not the case. When one constructs a multilayer model where the layer thickness is some small fraction of opacity—so the layers really are like layers and radiate up and down at the same temperature—one will find that a strong greenhouse effect emerges and that as more GHGs are added, the layers become thinner and more numerous and so back radiation to the surface tends , on average, to come from a lower, hotter layer and radiation out to space is emitted, on average, from a higher colder layer—and this will go on until the system warms until the higher layer is radiating to space the same net amount of energy coming in from solar. Just look to Venus to see how hot a planet’s surface can get—and, although closer to the Sun, Venus does this with less incoming solar due to its high albedo (the reason we can see it so easily). What is interesting about the history of the climate change issue is that once these two criticisms were cleared up, the President’s Science Advisory Council (PSAC) sent a report to President Johnson outlining the physics of the problem and the likely implications, and they got things pretty close (as did Arrhenius—who solved the multilayer equations algebraically by hand). PSAC’s report was in 1965—our understanding is so much further beyond your argument that assessments sometimes forget to keep offering the explanation, but it has proven very sound. Mike MacCracken On 6/12/09 10:43 AM, "[email protected]" <[email protected]> wrote: Amazingly you ignore the physics. When a black body such as the greenhouse layer gets black it achieves a maximum radiative output and feedback to the surface independent of how thick or concentrated it is. When the greenhouse gases in the atmosphere reach that level, putting in more greenhouse does not increase the greenhouse effect. The natural positive feedback of increasing CO2 levels saturates and the Earth's surface temperature no longer increases as a result of greenhouse effects. In the past the asymptotic average temperature has been about 25 C except about 250 million years ago when extensive lava flows in the area of Siberia (an asteroid impact near Antarctica triggered it) caused additional heating of several degrees and virtual extinction of surface life. From: Veli Albert Kallio [mailto:[email protected]] Sent: Friday, June 12, 2009 8:54 AM To: [email protected]; John Nissen; [email protected] Cc: Geoengineering FIPC Subject: RE: [geo] Re: Back to Nature Of the various views: One needs to keep in mind that the Paleocene-Eocene Thermal Maximum (PETM), 55 million years ago was effectively an "ALLDEAD" scenario where the release of carbon was not having any human help. A natural and an instrumented release of carbon totally different. It certainly is the greatest risk is that we continue to exhaust all the combustible carbon resources with an efficiency that will far exceed any natural event in the past that could have simultaneously released the fossilised carbon out of highly different geological stratum. The instrumented release of CO2 added to the natural positive CO2 feedbacks (i.e. such that occurred during the PETM), means the natural releases now taking place on top of the anthropogenic, instrumented CO2 release, constitutes a possibility of reduced rate of recovery unlike the PETM. There were no instrumented releases during PETM to empty CO2 from the rock strata of many geological ages at once. What needs to be understood is what triggered the PETM releases and can the human activity to restart this behemoth? David Keith's effective half-life of anthropogenic CO2 is many thousands of years as the geological system gets clogged beyond much larger anthropogenic concentration than at present, potentially opening a time for the massive releases of methane from the Arctic to be released. The climatic forcing, therefore, skyrocketing by several Watts/m-2. It is important to remember that the positive GHG feedbacks of PETM were effectively "ALLDEAD" scenarios with all carbon being released by the natural knock-on positive feedback effects alone. The man made exploitation of fossil fuel resources is a vital addition to the sum cumulative of the natural feed backs that could never have extracted carbon with same efficiency and geological stratum as fossil fuel exploitation has done. Therefore, it is irresponsible to state that the situation would stop at PETM levels, though substantial enough to justify the drastic actions, but as hydrological structures might become substantially altered in very much higher temperatures total pandemonium is conceivable and only appropriate to consider as the outcome. It bears to be kept constantly in mind that at one point the Mediterranean Sea dried to the bottom, and were the temperatures raised high enough the imbalance of liquid water and vapour could change. On changed conditions of substantial evaporation, sea floor pressures reverse and these kind of changes probably also helped the Paleocene-Eocene Thermal Maximum positive CO2 feedback if the sea water warmed very substantially, water then evaporating far more and CO2 seeping out of seas and volcanoes. This is an ALLDEAD-scenario with depressurised sea floor macro-fracturisation and volcanic seepages. But even PETM could not release fossilised carbon, only the carbon on sea water and exposed soils due to forestry die back and decay. More evaporation means also more flooding, and decay, these forces releasing carbon from land in far advanced global warming systems where forest died but soils continue to decay. Therefore, the super-hot state could occur and the Earth move beyond PETM state to ALLDEAD state due to the additional infrared hue of anthropogenic, instrumented release. But as there is no one then around to see it, I do not see too much point imagining what such a world as envisioned by Steven Hawkins +280C or James Lovelock +58C would be. But instrumented all-across-board geological stratum GHG releases did not occur during the Paleocene-Eocene Thermal Maximum, 55 Myr ago that is for sure. (So, equally sure, we are not bound by any PETM ceiling of natural feedbacks 'dying out' to a level of dinosaur climate where we could still put sun screen on the South Pole.) With kind regards, Veli Albert Kallio, FRGS From: [email protected] To: [email protected]; [email protected] CC: [email protected] Subject: [geo] Re: Back to Nature Date: Thu, 11 Jun 2009 20:12:47 -0400 I think you owe it to yourself to study (it takes only a few minutes) the website www.scotese.com <http://www.scotese.com/> Christopher Scotese is a well known, well respected geologist. Click on Climate and study the climate history for the past 540 million years (most of that time without humans). You will quickly be disabused of ideas that the warming continues to a super hot state. It gets into dinosaur temperature range but not beyond. From: [email protected] [mailto:[email protected]] On Behalf Of John Nissen Sent: Thursday, June 11, 2009 6:37 PM To: [email protected] Cc: [email protected] Subject: [geo] Re: Back to Nature No, it's all wrong - about the CO2 being absorbed from the atmosphere and the planet cooling. On the contrary, if we were all to drop dead tomorrow, global warming would continue for thousands of years, as I explain in the thread I started, about the GREAT LIE. There'd also be an immediate warming spurt, as the sulphur aerosol pollution (which has a cooling effect) would be quickly washed out of the atmosphere. And,within a few decades, on top of the CO2 warming would be the warming from methane as permafrost melted, and the sea level would rise 60-70 metres as Greenland and Antarctic ice sheets melted. Thus, if we disappear, or just carry on as we are for that matter, the Earth will continue tipping into a super-hot state, which probably won't be habitable for humans, even at the poles. However it is unlikely that the Earth will go the way of Venus, with the oceans boiling away, if that's any comfort. Cheers, John --- Alvia Gaskill wrote: http://en.wikipedia.org/wiki/Aftermath:_Population_Zero I recently saw the Nat. Geo program "Aftermath: Population Zero," one of several hypothetical accounts of what the world would be like without people. Not less people, no people. These seem to have been inspired by the work of Alan Weisman, author of the book "The World Without Us." http://en.wikipedia.org/wiki/The_World_Without_Us In addition to describing what would happen to domesticated animals and pets left without humans to take care of them, the fate of infrastructure is also presented. This particular program (there is another one that has been turned into a series on the History Channel called, appropriately enough, "Life After People" http://en.wikipedia.org/wiki/Life_After_People ; http://en.wikipedia.org/wiki/Life_After_People:_The_Series [for those people still not depressed enough after watching the original documentary]) also explores changes in the Earth's climate without its number one interferent, us. After 150 years, winters are colder than during the last days of humans with greater snowfall, indicating declining GHG levels. It is stated that the oceans will remove 13.5Gt of CO2 per year. Is this correct? After 200 years, the excess CO2 from human emissions is completely eliminated by plants and trees. Don't tell David Archer. Perhaps the increase in plant growth will speed the removal. Or won't that matter? After 500 years, forests return to the state they had 10,000 years ago. I doubt that one, as that would have been at the tail end of the ice age. After 25,000 years, the interglacial is over, the ice sheets return and erase NYC along with most of the areas wiped out before. Which raises an interesting question for the geo haters. If it became apparent that the interglacial was ending, would you be in favor of artificial means of prolonging it to ensure the planet's habitability for billions of humans? If you say no, then I think I'm going to propose to Nat. Geo or History a new series, Life After YOU People! <BR Beyond Hotmail - see what else you can do with Windows Live. Find out more. <http://clk.atdmt.com/UKM/go/134665375/direct/01/> _________________________________________________________________ Get the best of MSN on your mobile http://clk.atdmt.com/UKM/go/147991039/direct/01/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
