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 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 _________________________________________________________________ With Windows Live, you can organise, edit, and share your photos. http://clk.atdmt.com/UKM/go/134665338/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 -~----------~----~----~----~------~----~------~--~---
