probably I'm being stupid but it seems to me that if earth is tilted a bit more it will present more arctic to the sun in the northern summer and more antarctic to the sun in the southern summer ?? And ditto for elipticity (though I don't think it needs coincide with tilt?)??. As for precession, that's too much for me. Peter ----- Original Message ----- From: Eugene I. Gordon To: j...@cloudworld.co.uk ; anr...@nytimes.com Cc: agask...@nc.rr.com ; geoengineering@googlegroups.com ; wf...@virginia.edu Sent: Saturday, September 05, 2009 11:48 AM Subject: [geo] Re: we're engineering the arctic now
Again, I emphasize; be precise. We are in a warming period of the Milankovitch cycle, which afflicts mostly the Antarctic. However the same tilt cools the Arctic. The cycle will last another 10,000 years but it will not progress. From: geoengineering@googlegroups.com [mailto:geoengineer...@googlegroups.com] On Behalf Of John Nissen Sent: Friday, September 04, 2009 6:18 PM To: anr...@nytimes.com Cc: Eugene I. Gordon; agask...@nc.rr.com; geoengineering@googlegroups.com; wf...@virginia.edu Subject: [geo] Re: we're engineering the arctic now Hi Andrew, Interesting paper, you referred to, published in Science today (4th September). It seems to confirm the Ruddiman hypothesis [1] that we would be in a cooling period of the Milankovitch cycle, if it were not for (inadvertent) climate intervention by mankind. But Ruddiman takes a rather longer view, and considers temperature over the past 8000 years, which has remained pretty steady, allowing civilisations to develop. He shows that mankind's activities over this period have almost exactly countered a natural cooling that would have occurred from the Milankovitch cycles (concerning the Earth's orbit and tilt). But, since the start of industrialisation, we have injected an enormous pulse of CO2 into the atmosphere, as well as methane from livestock. These are already tipping the Earth's climate system towards a much hotter state. The global warming is amplified at the poles. An interesting point from the paper is that the Milankovitch cooling was starting to overcome anthropogenic warming in the Arctic at least two thousand years ago, until the last century, when polar amplification of global warming cut in and the cooling trend reversed. The abstract of the paper is here: http://www.sciencemag.org/cgi/content/short/325/5945/1236 Recent Warming Reverses Long-Term Arctic Cooling Darrell S. Kaufman,1,* David P. Schneider,2 Nicholas P. McKay,3 Caspar M. Ammann,2 Raymond S. Bradley,4 Keith R. Briffa,5 Gifford H. Miller,6 Bette L. Otto-Bliesner,2 Jonathan T. Overpeck,3 Bo M. Vinther,7 Arctic Lakes 2k Project Members The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ice Age. A 2000-year transient climate simulation with the Community Climate System Model shows the same temperature sensitivity to changes in insolation as does our proxy reconstruction, supporting the inference that this long-term trend was caused by the steady orbitally driven reduction in summer insolation. The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000. ---- The lesson is surely clear. We have to reduce the CO2 in the atmosphere and cool the polar regions if we are to restore the stability of climate (and sea-level) that we have enjoyed for the past 8000 years. Reducing emissions by itself will have little effect. Cheers from Chiswick, John [1] http://www.realclimate.org/index.php/archives/2005/12/early-anthropocene-hyppothesis/ Andrew Revkin wrote: Apologies to those who are not Dot Earth readers (and I *do* encourage everyone to have a look)... But just to make it clear to all, I do 98 percent of the comment moderation on the blog (no easy task) and there is NO screening or censorship (to the consternation of some, who feel the blog has been taken over by "climate skeptics"). If a comment is on topic and constructive and polite, it gets published. There *have* been significant technical glitches with a transition to a new comment mechanism, so many comments have been lost (by folks of all stripes). I always recommend keeping a copy of text instead of writing the comment in the submission box. Then it can be emailed to me as a backstop. At 8:54 AM -0400 9/4/09, Eugene I. Gordon wrote: Alvia: I too have been cut out of the Dot Earth comments and I have beencontributing for a few years. Andy asked me to e-mail him directly and Iexpect I will have to start doing that if he is careful to suppress my fullname, but whoever is screening appears to be anti Geoengineering. You missed one key point. All the climate variations are superimposed on topof an upward trend heading to 25 C even without CO2 increase. As you knowthis has happened at least 5 times during the 540 million year history ofthe Earth and is probably related to plate or land mass motion and how itinfluences ocean currents. No matter what they think about the dangers or risks (pretty stupid to thinkit would be implemented without risk assessment) geo will prove to beessential to block the increase. It is not going to be either or. -gene -----Original Message-----From: geoengineer...@googlegroups.com[mailto:geoengineer...@googlegroups.com] On Behalf Of Alvia GaskillSent: Friday, September 04, 2009 7:06 AMTo: anr...@nytimes.com; geoengineer...@googlegroups.comsubject: [geo] Re: we're engineering the arctic now I registered for Dot Earth, but for some reason, the message on thisparticular one won't allow me to log in. So I ask for you to post it if you wish. Without human interference, the interglacial would still take at leastseveral thousand years to end and the ice sheets to return to cover thenorthern hemisphere. With it, the interglacial continues. Most likely, the CO2 we have added to the atmosphere will have been removed by some form ofair capture in 100-200 years (sorry to disappoint David Archer et al.).Thus, we will have had no impact on preventing the return of the LaurentideIce Sheet and related ones in Europe and Asia. UNLESS we take the lessonslearned from our inadvertent intervention into the climate system and use it to our benefit. One of the definitions of geoengineering that is often used is that of"deliberate modification of Earth's environment on a large scale to suithuman needs and promote habitability." The needs of the present are to stop the effects of global warming before the planet becomes uninhabitable forhumans. Geoengineering in this instance is the use of technologies thatstop global warming without reducing emissions of CO2 and other greenhousegases. But once we can can control the CO2 level in the atmosphere, do we reallywant it to return to the pre-industrial level? Probably so. That was thelevel that allowed a stable climate and for human civilization to develop.At some point, probably thousands of years from now, we will want tocounteract the natural cycle and prevent the interglacial from ending. Bythen, we will have developed far more advanced technologies of all typesthan today and adjusting the climate will be relatively simple. Assuming we survive our current experience with global warming, we will be able to build on it and develop the technologies to modify climate to our needs, back tothe first definition. Not surprisingly, there are those on the environmental left who wouldwelcome the return of the ice sheets. One poster at the geoengineeringgroup even said he thought we should allow the ice sheets to cover Canadaand the northern U.S. again because the glaciers would scrape up moreminerals that could be used. Like we are expecting a shortage of iron andnickel in 8000 AD? He then went on to imagine that the survivors (NY Times won't be able topublish under 2 miles of ice, sorry Andy, must change name of blog to DotIce) could all go and live in the tropics, where, of course, food will still be limited due to changes in precipitation and in the subtropics, winds will howl most of the time. The ice age was no picnic, even in the southern U.S. How people come to view humans, their own species as the enemy beats me.We've made some mistakes and they have cost us and other species. But atleast we are on the path to the 12 step recovery program by recognizing wehave a problem. Is the answer to alcoholism to shoot all the drunks? An even more extreme view shared by many, but voiced by few (forunderstandable reasons) is that humans are an invasive species that shouldbe eliminated from the planet! Moi kudzu? Do I look like a zebra mussel to you? For this select crowd, I have come up with a suitable name. Cutterites.After the character in the BBC TV series Primeval, Helen Cutter, who becamesuch a misanthrope she went back in time and tried to eliminate all theearly humans. I'm sure Helen would not be in favor of continuing theinterglacial either. And what happened to her experiment in preventativeextinction? She was crushed by a dinosaur that followed her through one ofher time portals. Gotta watch out for that technology. It'll get you whenyou least expect it. Alvia GaskillPro-Human Lobbyist ----- Original Message -----From: "Andrew Revkin" <anr...@nytimes.com>To: <geoengineering@googlegroups.com>Sent: Thursday, September 03, 2009 3:40 PMSubject: [geo] we're engineering the arctic now http://www.nytimes.com/2009/09/04/science/earth/04arctic.html http://dotearth.blogs.nytimes.com/2009/09/03/humans-may-have-ended-long-arctic-chill/ we may be able to 'skip' the next ice age in fact. would love your thoughts in the comments section. -- Andrew C. Revkin The New York Times / Environment 620 Eighth Ave., NY, NY 10018 Tel: 212-556-7326 Mob: 914-441-5556 Fax: 509-357-0965 http://www.nytimes.com/revkin > ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.409 / Virus Database: 270.13.77/2346 - Release Date: 09/04/09 17:51:00 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
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