Hi All The folk in Tuvalu would not care much where the rising water came from or how fresh it was, only the change in sea level. This will propagate at a speed which is the square root of (g times the ocean depth) . If the globe had a uniform ocean depth of 1000 metres this is nearly 100 metres a second or 220 miles per hour. There might be a small effect of squeezing through the gap between South Africa and the Antarctic but we are talking about days, very short compared with the melting time.
Stephen David Schnare wrote: > Here's the cite and some abstracted information from the article on > speed of propogation of Greenland melt water into the pacific. It's > seems to take 80, not 100 years to reach the Pacific. Notably, > however, the water, once melted, is on the move. Thus, the time to > flooding only informs one on when to begin building the dike. The > study did not examine what would happen if the arctic ice began to > freeze up after a melt. > > d > > > > * > > Melting ice sheets will send slow wave around globe > > * > > • 09 July 2008 > > • From New Scientist Print Edition. > > > > If the ice caps melt, low-lying coasts will disappear beneath the > waves first, right? Not necessarily. The sea level "wave" takes time > to travel around the globe, so Pacific islands could get a temporary > reprieve, while Atlantic coasts bear the brunt. > > Many climate models predict that melting in Greenland could cause a > global sea level rise of more than a metre in the next century. This > would engulf Pacific islands such as Kiribati and Tuvalu. > > Yet Detlef Stammer of the University of Hamburg, Germany, says the > majority of Greenland's meltwater will stay in the Atlantic Ocean for > at least 50 years, causing sea levels here to rise faster than > expected. "The Greenland ice cap is much less of a threat to tropical > islands in the Pacific than it is for the coasts of North America and > Europe," he says. > > Stammer built a computer model based on Greenland's meltwater releases > since 1948, which showed that currents would carry the meltwater to > the tip of Africa before spilling east into the Indian Ocean, finally > reaching the Pacific Ocean 30 years later. > > After 50 years, sea level rise around Greenland and the east coast of > North America would be 30 times as great as in the Pacific Ocean, > whereas in Europe it would be six times as great ( > > /Journal of Geophysical Research/, DOI: 10.1029/2006JC004079). > > Antarctic meltwater could be prevented from reaching much of the world > for centuries due to strong currents in the Southern Ocean, says Stammer. > > ** > > - - - - - - - > > JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, C06022, > doi:10.1029/2006JC004079, 2008 > > * > > Response of the global ocean to Greenland and Antarctic ice melting > > D. Stammer > > * > > Institut für Meereskunde, Universität Hamburg, Hamburg, Germany > > * > > Abstract > > * > > We investigate the transient response of the global ocean circulation > to enhanced freshwater forcing associated with melting of the > Greenland and Antarctic ice sheets. Increased freshwater runoff from > Greenland results in a basin-wide response of the North Atlantic on > timescales of a few years, communicated via boundary waves, equatorial > Kelvin waves, and westward propagating Rossby waves. In addition, > modified air-sea interaction plays a fundamental role in setting up > the basin-scale response of the Atlantic circulation in its subpolar > and subtropical gyres. In particular, the modified ocean dynamics and > thermodynamics lead to a depression in the central North and South > Atlantic that would not be expected from linear wave dynamics. > Moreover, the heat content increases on basin and global scales in > response to anomalous freshwater forcing from Greenland, suggesting > that the ocean's response to enhanced freshwater forcing would be a > coupled problem. Other parts of the world ocean experience a much > slower adjustment in response to Greenland freshwater forcing, > communicated via planetary waves, but also involving > advective/diffusive processes, especially in the Southern Ocean. Over > the 50 years considered here, most of the sea level increase > associated with freshwater input from Greenland remains in the > Atlantic Ocean. In contrast, ice melting around Antarctica has a much > reduced effect on the global ocean. In both cases, none of the basins > came to a stationary state during the 50-year experiment. > > / > > Received 28 December 2006; accepted 18 March 2008; published 24 June 2008. > > /* > > Keywords: > > *ocean circulation; climate change; icecap melting.* > > Index Terms: > > *1616 Global Change: Climate variability (1635, 3305, 3309, 4215, > 4513); 1641 Global Change: Sea level change (1222, 1225, 4556); 4275 > Oceanography: General: Remote sensing and electromagnetic processes > (0689, 2487, 3285, 4455, 6934). > > On Tue, Dec 16, 2008 at 7:16 AM, David Schnare <[email protected] > <mailto:[email protected]>> wrote: > > John: > > I'll try to find it to give you the cite, but a paper came out > earlier this year indicating that a Greenland Ice Sheet total melt > would take in excess of 100 years to reach the bottom of Africa > and South America, and only then would we begin to see ocean level > rises in the Pacific and Indian oceans. Flooding concerns remains > first and foremost a problem for those of us on "the big pond" of > the Atlantic. > > David. > > On Mon, Dec 15, 2008 at 4:20 PM, John Nissen <[email protected] > <mailto:[email protected]>> wrote: > > And here is a plea for action, from His Excellence Alik Alik, > vice president of the Federated States of Micronesia. (Thanks > to Peter Read for pointing this out.) > > > http://www.islandsbusiness.com/news/index_dynamic/containerNameToReplace=MiddleMiddle/focusModuleID=130/focusContentID=13926/tableName=mediaRelease/overideSkinName=newsArticle-full.tpl > > "On behalf of the people of my islands, I demand action," Alik > told the round-table. > > "Are we showing that humankind is not capable of saving itself? > > "We are truly the victims not of our doing and you must help > us adapt to the impact of climate change." > > --- > > Of course, if, through geoengineering, we cool the Arctic, > save the Arctic sea ice, and prevent further destabilisation > of the Greenland ice sheet, we will help to prevent a sea > level rise for which the islanders would be unable to adapt. > > BTW, it should be possible to listen to a webcast of his > speech. Does anybody know how? > > John > > > ----- Original Message ----- > *From:* John Nissen <mailto:[email protected]> > *To:* Alvia Gaskill <mailto:[email protected]> > *Cc:* geoengineering > <mailto:[email protected]> ; David Appell > <mailto:[email protected]> ; Tim Lenton > <mailto:[email protected]> ; David Lawrence > <mailto:[email protected]> ; James Hansen > <mailto:[email protected]> ; Peter Read > <mailto:[email protected]> ; Davies, John > <mailto:[email protected]> ; > [email protected] > <mailto:[email protected]> > *Sent:* Monday, December 15, 2008 9:03 PM > *Subject:* Re: Are we near some kind of catastrophic > tipping point? > > Hi all, > > Perhaps it is our duty to act. We are not absolutely > certain that we face a catastrophic tipping point, but > that is not an excuse not to act, *nor to postpone our > actions*. But postponing actual geoengineering, by > carrying on research indefinitely, is exactly what we > appear to be doing. Instead we must *take the necessary > precautionary measures*, in particular geoengineering > deployment, to avoid the *threat of serious and > irreversible harm* that is contingent on the loss of the > Arctic sea ice, one of the *adverse effects of climate > change* that can be soon expected unless we act now. We > do not have to get the whole world to agree either. Here > is chapter and verse of UNFCCC Article 3.3. > > From GreenLearning > at http://www.greenlearning.ca/climate/policy/unfccc/1 > > [quote] > > > *Precautionary Principle* > > At the 1992 Rio Conference on Sustainable Development, the > United Nations formalized the precautionary principle > [external link] > <http://www.gdrc.org/u-gov/precaution-7.html>, which > recognizes that the absence of full scientific certainty > is not a good reason to postpone decisions when faced with > the threat of serious or irreversible harm. > > Article 3.3 [external link] > <http://unfccc.int/resource/conv/conv_005.html> of the > UNFCCC states that: "The Parties should take precautionary > measures to anticipate, prevent or minimize the causes of > climate change and mitigate its adverse effects. Where > there are threats of serious or irreversible damage, lack > of full scientific certainty should not be used as a > reason for postponing such measures, taking into account > that policies and measures to deal with climate change > should be cost-effective so as to ensure global benefits > at the lowest possible cost. To achieve this, such > policies and measures should take into account different > socio-economic contexts, be comprehensive, cover all > relevant sources, sinks and reservoirs of greenhouse gases > and adaptation, and comprise all economic sectors. Efforts > to address climate change may be carried out cooperatively > by interested Parties." > > > [end quote] > > I must thank Peter Read for drawing my attention to this > Article. > > Cheers from Chiswick, > > John > > > > > ----- Original Message ----- > *From:* John Nissen <mailto:[email protected]> > *To:* Alvia Gaskill <mailto:[email protected]> > *Cc:* geoengineering > <mailto:[email protected]> ; David > Appell <mailto:[email protected]> ; Tim Lenton > <mailto:[email protected]> ; David Lawrence > <mailto:[email protected]> ; James Hansen > <mailto:[email protected]> > *Sent:* Monday, December 15, 2008 3:48 PM > *Subject:* Are we near some kind of catastrophic > tipping point? > > > Hi Alvia, > > Thanks for the reference to Daivd Appell's article. > > http://www.guardian.co.uk/commentisfree/cifamerica/2008/dec/12/environment-climate-change-poznan > which you quote (see appended email). > > I agree with David that there is not a "sense of > crisis", but I think there should be, and strongly > disagree with the following statement: > > *"Those claiming we are near some kind of catastrophic > tipping point simply have no science to back up their > claims." > * > Wrong. There is very clear science to back up this > possibility. > > There are clear signs that the whole Earth system is > tipping into a new super-hot state, due to the very > large pulse of anthropogenic CO2 put in the > atmosphere. Hansen suggests a global tipping point > could be reached by 2016, unless action is taken: > http://www.ens-newswire.com/ens/jun2007/2007-06-01-01.asp > > And this is tantamount to a planetary emergency: > > http://www.cleanenergy-project.de/2008/04/29/tipping-point-%E2%80%A2-perspective-of-a-climatologist-james-hansen/ > > Within this overall tipping of the Earth system, > taking place over decades, there may be individual, > quicker acting, tipping points, helping the Earth > system along its way. > > We can consider a number of individual tipping points, > with ref to Prof Tim Lenton's paper: > > http://researchpages.net/ESMG/people/tim-lenton/tipping-points/ > > 1. The summer disappearance of Arctic sea ice > > "A more convincing case can be made that climate > warming may have caused the Arctic sea-ice to pass a > tipping point. Certainly the area coverage of both > summer and winter Arctic sea-ice are declining at > present, summer sea-ice more markedly, and the ice has > thinned significantly over a large area. Elegant > analysis has shown that positive ice-albedo feedback > (the warming due to changing from reflective ice to > dark ocean surface) dominates over external forcing > (the global warming signal) in causing the thinning > and shrinkage since around 1988. This suggests the > system may already be undergoing a non-linear > transition toward a different state with less Arctic > sea-ice (perhaps none in summer)." > > 2. The Greenland ice sheet > > "The tipping element that consistently emerges as > having the closest threshold (in terms of global > warming) and the least uncertainty in this is > (irreversible) melt of the Greenland Ice Sheet (GIS). > Paleo-data reveal that the GIS shrunk considerably > during the last interglacial. Models also indicate > that above a local warming of ~3 °C above present the > Greenland ice sheet will go into net mass loss and > shrink to a much smaller size (perhaps disappearing > altogether). The corresponding global warming > (accounting for polar amplification) is estimated at > 1–2 °C. The IPCC (2007) give a more conservative range > of 1–4 °C. Others have estimated <1 °C. Their case may > be bolstered by observations indicating that the ice > sheet is already in net mass loss and the rate of mass > loss has accelerated in the last decade. The timescale > for the ice sheet to melt is at least 300 years and > often given as roughly 1000 years. However, given that > it contains 7m of global sea-level rise the > corresponding contribution to sea-level can dwarf > other contributors." > > 3. The WAIS > > "The West Antarctic Ice Sheet (WAIS) is thought to be > less vulnerable to warming than the Greenland Ice > Sheet but a threshold could still be accessed this > century. The setting is quite different, with most of > the WAIS grounded below sea-level. The WAIS has the > potential to collapse if grounding line retreat causes > ocean water to undercut the ice sheet and trigger > further separation from the bedrock (a strong positive > feedback). This suggests that it is warming ocean > water rather than a warming atmosphere that may pass a > critical threshold, a point bolstered by the fact that > for surface melting to occur, there would need to be > ~8 °C warming of the surface atmosphere at 75–80 °S to > reach the freezing point in summer. The corresponding > global warming depends on the Antarctic polar > amplification factor (which varies a lot between > models for the 21st century but is likely much smaller > than that for the Arctic). The threshold for ocean > warming is estimated at 3–5 °C. A worst case scenario > is for collapse to occur within 300 years, with a > total of 4–6m of global sea-level rise." > > 4. The Amazon > > "One region that would suffer drying is the Amazon, > and more persistent El Niño conditions have been > predicted to cause dieback of the Amazon rainforest > under 3–4 °C global warming in the Hadley Centre > model. A recent study nesting a regional climate model > within a different GCM also predicts Amazon dieback > due to reductions in precipitation and lengthening of > the dry season. When different vegetation models are > driven with similar climate projections they also show > Amazon dieback. However, other climate models predict > different precipitation trends and therefore do not > produce dieback. Rainforest loss itself leads to > reductions in precipitation, so land-use change could > be a trigger, as well as climate change. The > transition time is of the order of decades and the > impacts include widespread loss of biodiversity." > > 5. Methane from permafrost > > "North from the boreal forest lies the tundra, but as > already discussed, melt of the permafrost and > associated methane release – and on longer timescales, > replacement of the tundra by boreal forest – are > expected to be quasi-linear responses and therefore > not tipping elements." > > However, the global warming from massive methane > release would trigger further release, in a runaway > global warming event - perhaps not a tipping point, > but a point of no return. And David Lawrence is not > as sanguine about the timescale, see below. > > 6. Domino dynamics > > "Current mechanistic understanding suggests that there > are more positive causal connections between tipping > elements than negative ones. In the worst case > scenario, this raises the alarming possibility of > 'domino dynamics' in the climate system where tipping > one element encourages tipping the next and so on. > However, lest the reader be panicking, there are also > notable negative interactions between tipping elements > that could produce 'self-regulation' scenarios. > Furthermore, Earth history indicates that transitions > of the whole Earth system are rare." > > "Continuing... if the GIS starts to melt the ensuing > sea level rise will encourage grounding line retreat > of the West Antarctic Ice Sheet (WAIS). Furthermore, > if there is a collapse of the THC promoted by GIS melt > this would tend to warm the Southern Ocean also > encouraging disintegration of the WAIS. Hence there is > the possibility of domino dynamics between the > Greenland and West Antarctic ice sheets. " > > The release of methane is likely to be triggered by > the loss of Arctic sea ice, according to David Lawrence: > http://www.ucar.edu/news/releases/2008/permafrost.jsp > > Similarly the disintegration of GIS is likely to be > promoted by the loss of Arctic sea ice, partly because > of the albedo effect, but also because the sea ice > forms a physical barrier to the glacier outlets. > > 7 Timescale > > The shortest timescale is likely to be for the Arctic > sea ice summer disappearance, which then can have a > domino effect on methane release and Greenland ice > sheet disintegration. > > The Climate Safety report says that "many scientists > are now predicting an ice-free summer Arctic by > somewhere between 2011 and 2015." The refs below are > from the full report, downloadable from: > http://www.indymedia.org.uk/en/2008/12/414238.html > > [15] Kathryn Young, "Canada's Inuit facing 'cultural > genocide,' says Arctic expert", Canada.com, 23 > November 2007. Available online at: > > http://www.canada.com/cityguides/winnipeg/info/story.html?id=886e1d36-01c8-4ef6-8d60-a9460b815f62&k=34394 > > <http://www.canada.com/cityguides/winnipeg/info/story.html?id=886e1d36-01c8-4ef6-8d60-a9460b815f62&k=34394> > > > [16] Steve Connor, "Scientists warn Arctic sea ice is > melting at its fastest rate since records began", > Independent, 15 August 2007. Available online at: > > http://www.independent.co.uk/news/science/scientists-warn-arctic-sea-ice-is-melting-at-its-fastest-rate-since-records-began-461632.html. > > [17] Andrew C. Revkin, "Retreating Ice: A blue Arctic > Ocean in summers by 2013?", International Herald > Tribune, 1 October 2007. Available online at: > http://www.iht.com/articles/2007/10/01/ > > <http://www.iht.com/articles/2007/10/01/sports/arcticweb.php>sports/arcticweb.php. > > > Cheers from Chiswick, > > John > > > ----- Original Message ----- > *From:* Alvia Gaskill <mailto:[email protected]> > *To:* [email protected] > <mailto:[email protected]> > *Sent:* Saturday, December 13, 2008 10:31 PM > *Subject:* [geo] Time to Call In Klaatu and Gort? > > > http://www.guardian.co.uk/commentisfree/cifamerica/2008/dec/12/environment-climate-change-poznan > > Let's get real on the environment. > > After the failure in Poznan, it's time to be honest: > the world is not going to be cutting greenhouse gases > anytime soon > > *David Appell* > <http://www.guardian.co.uk/profile/david-appell> > guardian.co.uk <http://www.guardian.co.uk/>, Friday 12 > > The world's environmental leaders have spent the past > two weeks meeting in Poznan, Poland, pretending that > they're carrying on the fight against global warming > > <http://www.guardian.co.uk/environment/2008/dec/12/poznan-climatechange> > first addressed by the Kyoto Protocol. > > You recall the Kyoto Protocol. It was never ratified > by the United States > <http://www.guardian.co.uk/world/usa> – defeated 95-0 > in the US Senate in 1997, in fact – and has proven > just as ineffective elsewhere around the world. It was > supposed to be first step in the world's cutback of > greenhouse gases like carbon dioxide that are warming > our atmosphere. > > The hard truth be told, essentially none of those who > signed onto the treaty have been able to cutback their > greenhouse gas emissions. > People – surprise, surprise – demand to be warm at the > cheapest prices. Developing countries like China and > India have ignored it completely, with their emission > rising at 6% to 8% a year. China now emits more > greenhouse gases than even the United States. > > Carbon dioxide emissions, which were increasing about > 1% a year in the 1990s, are increasing about 3% > percent a year in this decade. Leaders all across the > world, including Barack Obama, continue to look > straight into the camera and proclaim that they are > going to solve the global warming crisis – by 2020, or > 2050, or 2100 or … sometime soon. > > The world desperately needs to get serious, including > President-elect Obama, Europe's leaders and every UN > bureaucrat who dined handsomely in the evenings in > Poznan. The truth is, the world is not going to be > cutting greenhouse gases anytime soon. If ever. > > There are simply no reasonable alternatives. Wind > power is too scant. Nuclear power is too > controversial. Solar power is stuck in a dream world. > It gets a little better every year, but it will never > be good enough. Nuclear fusion is hopeless, > perpetually 25 years in the future. > > Not one of us – you, me, Obama or the greenest > activist anywhere in the world – is willing to live > without the comforts fossil fuels provide us – heat, > light, instant hot food, convenient transportation, > modern agriculture and airplane travel. > > There are too many factors pointing strongly in the > wrong direction: the demonstrated refusal of western > countries to sacrifice in the face of the climate > problem they created; the insistence of developing > countries that they be able to live at least as well > as the US and Europe and their unwillingness to cut > back greenhouse gas emissions as long as first world > countries – who largely created this mess – refuse to > do so. The lack of any reasonable alternatives, and > our lack of interest in developing them, further > hinders the ability to find a solution. > > We are never going to live as cheaply as we possibly > can, especially here in the US, and we simply do not > have the wisdom to sacrifice for the sake of those who > will live decades ahead of us. From the time we landed > on the Atlantic coast and pushed westward, it is > simply not bred in the American bone. > > Obama will not change this. Americans will not accept > large increases in what we pay for gasoline and > electricity. President-elect Obama says he is going to > solve the financial crisis, the healthcare crisis, the > infrastructure crisis, the energy crisis, the climate > crisis and perhaps even the intolerable shortage of > magic pixie dust. > The man is quite the optimist. But let's not be > completely stupid. > > Our problems, especially the climate crisis, are not > going away anytime soon. The alternative technologies > we need to reduce our > > <http://www.washingtonpost.com/wp-dyn/content/article/2008/03/09/AR2008030901867.html>carbon > emissions > <http://www.guardian.co.uk/environment/carbonemissions> > to essentially zero – what scientists are now telling > us is necessary – simply aren't there, and won't be > anytime soon. > > Nor is the sense of crisis really there. Those > claiming we are near some kind of catastrophic tipping > point simply have no science to back up their claims. > > Those expecting that we are going to reduce our > atmosphere's carbon dioxide content to 350 parts per > million are naïve activists perhaps living off the > donations to their organisations. In any case, they > are dreaming in la-la land. > > There is no crisis that will change our minds – not > heat waves in France, not Katrina, not the > disappearance of Arctic ice up north. We want what we > want, and our species is lousy at planning for the future. > > Even the world's climate organisers do not hesitate to > fly thousands of miles to Poland and live high on the hog. > > Given this, what can we do? Be realistic, first of > all. Let's fund geo-engineering research to the hilt, > exploring how we can someday modify our planet's > natural systems to produce a slight atmospheric > cooling. It is our destiny. > > But most of all, let's open our eyes and begin to be > honest. You will fly to Jamaica this winter instead of > cutting your greenhouse gases. Fine. Can we please > accept this and begin to move on? > > > > > > > > -- > David W. Schnare > Center for Environmental Stewardship > > > -- Emeritus Professor of Engineering Design School of Engineering and Electronics University of Edinburgh Mayfield Road Edinburgh EH9 3JL Scotland tel +44 131 650 5704 fax +44 131 650 5702 Mobile 07795 203 195 [email protected] http://www.see.ed.ac.uk/~shs The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
