[geo] Re: Terrestrial Ice In West Greenland Under Attack from Weather

[John Nissen]

Hi Andrew, I'm not saying "now or never", but I am saying "the sooner the better", because (1) it is a question of risk reduction and  (2) countering positive feedback is best before the feedback has grown too much. Scientists have spent a tremendous effort in persuading the politicians and media that emissions reductions, of the kind "80% by 2050", can keep the global warming below 2 degrees.  But even if we could achieve such a target in every country in the world, it wouldn't save the Arctic sea ice - and hence it would not prevent outgassing of methane and disintegration of the Greenland ice sheet.  So how much cooling can geoengineering provide? Albert writes:  "I am increasingly concerned that temperatures at around +24C, can't be tamed by sulphur dioxide or other means, it just could be a magnitude or several times more than the negative feedback induced by the geoengineering methods. I fear the not enough scenario." (see reproduced email below) The Arctic is warming twice as fast as the rest of the globe, in a process known as "polar amplification".  This process appears to be driven by "albedo flip".  As sea ice is replaced by water, the reflectivity, or "albedo", changes by up to 70%, giving greater absorption of solar energy, April through September.  Suppose the use of enough stratospheric sulphur-based aerosols can cause a reflection of 20% solar energy.  It would have to be deployed over 3 times the area that the Arctic sea ice is melting in summer to counter the albedo flip.  That's my very rough calculation. Once the sea ice is all melted, it may be impossible to rescue the situation through any amount of geoengineering with stratospheric aerosols.  And then we are left helplessly with methane outgassing and Greenland ice sheet disintegration - beyond the point of no return. This is what is worrying me, and I think Albert too. Cheers, John --- Andrew Lockley wrote: I think it would be great if someone could bring forward a paper on the 'limits of geoengineering'.  John Nissen has made much play of the 'now or never' argument.  I have no opinion as to whether he's right or not, and I would love to see scientists with appropriate expertise bring forward a relevant paper. A 2009/7/6 Veli Albert Kallio <albert_kal...@hotmail.com> Dear Alan,   It is not only melting of sea ice and permafrost that needs to be highlighted.   Today's Temperature Legend Map from Foreca shows that Ilulissat Ice Fjord that drains 7% of Greenland ice sheet bathin on top temperatures today between +20-25C. This is substantial heat on the glacier, the morning temperatures shown are littel more moderate.   Last time I saw these kind of temperatures +24C in Ellesmere Island, the Aylers Ice Shelf collapsed on that particular week. The heat and warm water does damage ice considerably and I expect that Greenland's temperatures are much like the Baffin Island's once Arctic Ocean's sea ice is gone. I think today's weather is a good indicator what shall become.   I am increasingly concerned that tempeartures at around +24C, can't be tamed by sulphur dioxide or other means, it just could be a magnitude or several times more than the negative feedback induced by the geoengineering methods. I fear the not enough scenario. I don't want to be devil's advocate, but weather's could rise too high and out of control. Let's hope this peak heat stays short, but I would not be surprised if glaciers speed up once again. Kind regards,   Albert   --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---