Hi dsw_s,
You are right about the relative size of heat flux compared to albedo effect, but it is the _change_ in heat flux which is important to compare, e.g. any increased heat flux from the Gulf Stream entering the Arctic Ocean. Anyway, whatever is the root cause of Arctic shrinkage, it is happening a lot fast than IPCC predicted only a couple of years ago, and the trend shows no signs of reversing. Exactly the opposite - it has shown signs of accelerating this decade. There are recognised to be various cycles of the northern hemisphere ocean-atmosphere system, but we certainly cannot rely on such a cycle to rescue us by reducing heat flux into the Arctic and switching off the sea ice retreat. We can indeed expect surprises, but we cannot rely on them being pleasant ones! Indeed, most have been extremely unpleasant, of late. Thus the urgency for geoengineering is, if anything, increased, taking into account the precautionary principle. Cheers, John ----- Original Message ----- From: "dsw_s" <[email protected]> To: "geoengineering" <[email protected]> Sent: Friday, February 06, 2009 1:04 PM Subject: [geo] Re: runaway arguments ripped to bits >The "forcing" from the sea ice albedo effect is of the order of 30 Watts >per square metre, so you expect this to drive regional warming.< I expect surprises. How does the total number of watts of forcing compare with variability in heat fluxes into and out of the region? What other feedbacks are there that we haven't thought about? The vapor pressure over ice is less than over water at the same temperature, and the surface of ice can be cooler than the water below. So evaporation will presumably be greater over open water than it has been historically over the sea ice. If that water condenses elsewhere, that's a heat flux out of the region. Let's say we lose ten million square km of sea ice: that's 30 terawatts of forcing. But it looks as though there's over a petawatt of annually-averaged heat flux into the region, just by eyeballing a figure in a badly-out-of-date textbook. So with even a modest relative change in heat fluxes, the effects of the forcing could show up somewhere else rather than regionally. Or the regional effects could be an order of magnitude greater than the forcing would produce directly. For a conclusion about that, I would be more convinced by a peer-reviewed analysis of a detailed model than by the simple-and- obvious argument. On Feb 6, 6:49 am, "John Nissen" <[email protected]> wrote: > Hi Andrew, > > It depends what kind of proof you want. I myself am convinced of things if > there is a logical argument based on established facts. > > I am convinced by anthropogenic global warming because if you put an extra > 100 ppm CO2 in the atmosphere, you EXPECT to have greenhouse warming. I > don't need "proof" to be convinced. To be persuaded otherwise, I would > need a convincing explanation of why the CO2 wasn't causing global > warming, or how this was somehow neutralised. I would need to be PROVED > WRONG. > > Similarly with methane runaway feedback. There's a vast amount of methane > trapped in frozen structures. Nobody disputes this fact. If you put enough > of this methane in the atmosphere, you expect global warming. You then > expect positive feedback as a result of this, as the frozen structures > unfreeze to release more methane until it's all gone. Unless there is an > argument against this logic, I will remain convinced by it. > > Similarly with the Arctic sea ice and domino effects. The "forcing" from > the sea ice albedo effect is of the order of 30 Watts per square metre, so > you expect this to drive regional warming. Nobody is suggesting how this > warming would reverse naturally. So, as the region continues to warm, you > expect the domino effects of methane release and Greenland ice sheet > accelerated discharge. > > This is all highly uncomfortable to contemplate, and I'd like to be proved > wrong. However we do have a possible way out of this situation with > geoengineering. So all is not lost. > > Please can we now persuade politicians and potential funding bodies of the > inescapable logic of this situation, so that they fund the necessary > geoengineering developments? Or prove me wrong. > > Cheers, > > John > > ----- Original Message ----- > From: Andrew Lockley > To: John Nissen > Sent: Friday, February 06, 2009 1:13 AM > Subject: Re: [geo] runaway arguments ripped to bits > > I'm not saying you're wrong. I'm just saying I haven't been able to PROVE > you're right. > > A > > 2009/2/5 John Nissen <[email protected]> > > Dear Andrew, > > That is very unfair - a stab in the back. > > 1. I have given you several references to methane in the past, e.g. from > David Lawrence. And there are plenty of references already in wikipedia, > e.g. here: > http://en.wikipedia.org/wiki/Arctic_methane_release > (I am sorry I can't help on the shoreline slumping.) > > 2. I am trying to answer your basic question: Is there REALLY a big and > immediate risk from the clathrate gun/permafrost? You seemed to be arguing > only about the methane, without taking into account the Arctic sea ice > albedo effect. > > 3. The argument that the Arctic sea ice albedo effect is causing regional > runaway feedback is new to this list. The argument that we should reverse > the Arctic sea ice retreat is also new - previously I had argued we simply > had to halt the retreat. > > 4. These are common sense arguments. If anybody can find some evidence to > dispute them, may they come forth. > > 5. I have given my own conclusion repeatedly, because it bares repeating: > > If we do not act quickly with our SRM geoengineering, then thermal runaway > from methane (and also disasterous sea level rise) could become > inevitable. > > 6. Your criticism is a stab in the back, because you seemed to be one of > the few people who accepted this conclusion, because of all the evidence I > gave you. > > Et tu, Brute. > > John. > > ----- Original Message ----- > From: Andrew Lockley > To: John Nissen > Cc: Geoengineering FIPC ; Prof John Shepherd ; John Gorman > Sent: Thursday, February 05, 2009 1:12 PM > Subject: Re: [geo] runaway arguments ripped to bits > > John, > You've repeated these arguments on this list on numerous occasions. > However, you've failed to back them up with peer-reviewed science. > > I've already emailed the list asking for scientific support for these very > ideas in the last 24hrs. Specifically we need help with the alterations to > methane GWP, the decay rate of clathrates due to shoreline slumping in the > Arctic and calculations of the overall warming load arising from a methane > pulse. > > I hope you can assist with the search for solid backing for your case and > not re-iterate oft-rehearsed arguments. > > The relevant wiki is actually > athttp://en.wikipedia.org/wiki/Runaway_climate_change#Current_risk > > A > > 2009/2/5 John Nissen <[email protected]> > > The term "runaway" has an accepted meaning in the context of "thermal > runaway", and is characterised by positive feedback and resulting > acceleration in temperature change. So the temperature rises more than > linearly, and may even rise exponentially or "explosively": > http://en.wikipedia.org/wiki/Thermal_runaway > Eventually the feedback peters out, and the temperature change becomes > linear again. > > This process is happening with the Arctic sea ice. At present the albedo > feedback effect is causing an acceleration in temperature change in the > polar region - but this positive feedback will eventually peter out, when > all the ice and snow in the region has melted, including the Greenland ice > sheet! So we are facing thermal runaway on a regional scale, affecting > local climate and ecosystem. This will have a domino effect on methane > release. > > As the Arctic region warms, methane will invitably be released in larger > and larger quantities. The speed of methane release depends critically on > the temperature above the frozen structure holding the methane. For > permafrost on land, if the average surface temperature is maintained above > freezing, the permafrost will inevitably melt. This is what is happening > over vast areas of Canada and Siberia, as the isotherms (lines of equal > temperature on a map) move northwards. > > The methane itself provides feedback equally to both regional and global > warming, through its greenhouse effect. The regional warming will increase > the rate of methane release. Thus there could be thermal runaway on a > global scale and "we are toast", as Hansen puts it. > > We have to find a way to quickly halt the Arctic regional warming. I > maintain that the key to this is to halt and partially reverse the retreat > of the Arctic sea ice, by cooling the region. And I maintain that the key > to cooling is use of solar radiation management (SRM) techniques - a > combination of stratospheric aerosols and marine cloud brightening. > > If we do not act quickly with our SRM geoengineering, then thermal runaway > from methane (and also disasterous sea level rise) could become > inevitable. > > Cheers from Chiswick, > > John > > P.S. Note that geoengineering to reduce atmospheric CO2. > > ----- Original Message ----- > From: "Andrew Lockley" <[email protected]> > To: "Geoengineering FIPC" <[email protected]> > Sent: Thursday, February 05, 2009 2:28 AM > Subject: [geo] runaway arguments ripped to bits > > > After getting thoroughly shouted at, I realised I needed to improve my > > 'runaway' arguments. > > > My current skeleton is below. However, it's currently missing a few > > crucial bones which now need replacing. I need citations for the > > following: > > > 1) A clathrate gun effect that shows rapid release? Buffett and > > Archer, and Archer alone, show a slow release, although from a large > > reservoir. > > 2) A calculation of the eventual warming that may result from methane > > release from permafrost/clathrates. > > 3) A study showing the impacts of such a level of warming on human > > civilisation/survival. > > 4) What happens to methane sinks under conditions of bulk outgassing? > > Do they fail and massively increase the global warming potential of > > methane? > > > We've discussed all these issues before, but I think it's now time to > > get any available research on the issue into the open. Is there > > REALLY a big and immediate risk from the clathrate gun/permafrost? > > > A > > >http://en.wikipedia.org/wiki/Effects_of_global_warming#Abrupt_climate... > > > The scientific consensus in the [[IPCC Fourth Assessment Report]] is > > that "Anthropogenic warming could lead to some effects that are abrupt > > or irreversible, depending upon the rate and magnitude of the climate > > change." > > > The phenomenon of [[Arctic shrinkage]] is leading some scientists to > > fear that a runaway climate change event may be > > imminent<ref>http://www.guardian.co.uk/environment/2006/oct/18/bookextracts.books</ref>, > > and may even have > > started<ref>http://www.terranature.org/environmentalCrisis.htm</ref>. > > There is an [[albedo]] effect, as white ice is replaced by dark ocean. > > Rapid [[Arctic shrinkage]] is occurring, with 2007 being the lowest > > ever recorded area and 2008 being possibly the lowest ever recorded > > volume.<ref>http://nsidc.org/news/press/20081002_seaice_pressrelease.html</ref> > > This will induce or accelerate other [[positive feedback]] mechanisms, > > such as [[Arctic methane release]] from melting [[permafrost]] and > > [[clathrates]]. Lawrence et al(2008) suggests that a rapid melting of > > the sea ice may up a feedback loop that rapidly melts arctic > > permafrost.<ref>http://www.ucar.edu/news/releases/2008/permafrost.jsp</ref><ref>{{Citation > > | year=2008 | title=Accelerated Arctic land warming and permafrost > > degradation during rapid sea ice loss | first=David M. | last=Lawrence > > | > > ... > > read more ยป --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
