>There is pretty good evidence based on past climate history that long term >temperature > changes occur monotonically on a scale of thousands of years but not for > shorter times
Really? I had thought the opposite, from badly-out-of-date information. I think it was some series of measurements of oxygen isotopes that was talked about in an undergrad course, looking as though larger versions of year-to-year changes like El Nino happened at transition points and then never went back. On Feb 6, 8:43 am, "Eugene I. Gordon" <[email protected]> wrote: > I agree with Andrew. A positive feedback is not a runaway mechanism unless > it does not saturate. For sure 540 million years of temperature history show > there are long term temperature maxima and minima. That is not runaway. The > positive feedback is clear but it saturates. If we are engineers let us be > accurate and not fall back on careless prior nomenclature. There is pretty > good evidence based on past climate history that long term temperature > changes occur monotonically on a scale of thousands of years but not for > shorter times so there is slow positive feedback that saturates (not runaway > not even a slow jog.). > > As also a scientist I never fall back on hypothesis until it passes certain > requirements that elevate it to theory (logical arguments based on > established fact is not enough) . Comfort is fine but it is too casual. I > think a more professional approach is to use the word "suggests" or "is a > reasonable but not yet proven hypothesis." or :"is attractive but more work > is needed." > > _____ > > From: [email protected] > [mailto:[email protected]] On Behalf Of Andrew Lockley > Sent: Friday, February 06, 2009 7:28 AM > To: John Nissen > Cc: geoengineering > Subject: [geo] Re: runaway arguments ripped to bits > > You might be convinced by this hypothesis, but science works by proof. All > we have been able to demonstrate is a risk, not a probability. > > It's all a matter of gain. A positive feedback is NOT a runaway. It is > only a runaway if the gain is sufficient. You need to prove the gain to > prove the argument. > > Bearing in mind the water seems to re-freeze each winter, the feedback does > not seem to be the principle forcing mechanism in operation here. The > feedback may well dramatically accelerate the effect of CO2 emissions, but > it does not seem to be the central effect. Fortunately, as the Arctic is > dark for 6mo the system has plenty of time to recover from any seasonal > runaway. Can you cite papers to show the ice-albedo feedback is sufficient > to start a runaway effect? Which paper are you taking the 30W/m2 from? > > The methane effect similarly is unproven. This doesn't mean it's not true, > just that you haven't demonstrated it to be true. I can find no papers > which show a rapid degeneration of clathrates. Buffett and Archer > specifically failed to show such an effect, but I understand that they > considered only deep clathrates which are slow to outgass. Permafrost > slumping may be a crucial mechanism in faster degeneration of clathrates, > but has anyone modelled it and the outgassing rates that result? > > I can also find no papers which give the original research for the effect of > increased atmospheric methane. I personally don't really need to be > convinced that a massive outgassing of methane might be a slight problem, > but others do. Can you cite papers which indicate the expected temperature > increase from a predicted outgassing event? > > Don't take this all personally, John. I believe you're right. We just need > to prove it. This is science, not dogma. > > A > > 2009/2/6 John Nissen <[email protected]> > > 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 <mailto:[email protected]> > To: John Nissen <mailto:[email protected]> > 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 <mailto:[email protected]> > To: John Nissen <mailto:[email protected]> > Cc: Geoengineering FIPC <mailto:[email protected]> ; Prof > John Shepherd <mailto:[email protected]> ; John Gorman > <mailto:[email protected]> > 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 > > ... > > read more » --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
