[geo] Re: Robeson Channel Suitable for Suspension Cabling to Block Prevent Southward Ice Movement

[John Nissen]

Hi all, Some time ago, Albert and I discussed cables and barriers at length - and at a length to cross straits.  You really want a valve, that will let ice flow in one direction (North) but not the other (South).  It's quite difficult to do that with a cable. My thoughts are that a floating barrier might be best.  It can be rounded and point into the ice, so that ice pressure becomes a compression of the barrier.  Basically what you want is to create an ice jam of ice flows (or icebergs) on one side of the barrier which would then take most of the pressure as the ice builds up.  The barrier could be made across a fjord or across straits. The barrier would be made of sections, so it could come apart to let ice flow in the opposite direction (possibly in two sections, like canal lock gates).  The barrier could possibly be made out of pykrete [1], which has excellent compressional strength (over twice as strong as normal ice) and good tensile strength as well (much better than concrete) to give it rigidity, while having a density less than water so it floats (just). One major problem with such a barrier (across straits) could be when the wind is from the North, while the sea current is from the South, keeping the barrier open. BTW, I've seen recent research suggesting that there is a stable weather condition which can sit over the North Pole, with winds which tend to disperse the ice.  This condition is considered to have been instrumental in the unprecedented sea ice retreat in 2007.  Perhaps one of you can find a reference, please. Cheers from Chiswick, John [1] http://en.wikipedia.org/wiki/Pykrete Mike MacCracken wrote: What about doing this across Jakobshaven and other fjords that allow ice streams to flow rapidly? Mike On 10/1/09 9:25 AM, "Veli Albert Kallio" <albert_kal...@hotmail.com> wrote: Dear All, Please find enclosed a brief satellite animation on the Robeson Channel from this summer which suggest that use of bridge-style suspension cabling could hold ice in place and prevent it moving into the warm waters further along the channel between Ellesmere Island and Greenland. The link attached below which shows the summertime ice movements.   The shortest suspension cables would be Ellesmere - Hans Island - Greenland each stretch about 10 kilometres in length. (The concept is to create ice congestion behind barrier that is self-locking jam of pack ice behind cable that remains longer in the cold waters.)   On the negative side, the ice amount south of any successful cable barriers will decrease. The impact of cables for boats, whales and perhaps other large fish and wild life would also have to be addressed. After melting, the barrier cable is lowered to the seafloor when ice is on northward move or there is a lack of ice, the barrier is raised up to surface whenever there is ice flow moving southward. It is also raised up to surface for the winter freeze.   In Nunavut, the suspension cabling could help to keep the North West Passage clear of thick sea ice floes that damage ships while preserving ice on the north side of the channel. This might help justify such a system at least in Nunavut. The profile of the Swalbard Islands and Franz Joseph Land could also be enlarged by blocking the straights by cables. This would increase the ice congestion behind these archipelagoes and decrease some sea ice escape from the high Arctic Basin.   I have not considered blocking of the Fram Staight due to its width, but materially the largest amount of sea ice loss through escape will occur there. The barriers can slow down ice movement and loss to the south due to decreases in ice movements but if ice melts away due to warm weather behind barrier, these measures become all but useless.   Kind regards,   Albert From: janne.bjorkl...@sll.fi To: albert_kal...@hotmail.com Subject: Greenpeace dokumentoi pohjoisen pallonpuoliskon jäätiköiden sulamista Date: Thu, 1 Oct 2009 14:18:14 +0300 http://www.greenpeace.org/finland/fi/mediakeskus/lehdistotiedotteet/greenpeace-dokumentoi-pohjoise <http://www.greenpeace.org/finland/fi/mediakeskus/lehdistotiedotteet/greenpeace-dokumentoi-pohjoise>         View your Twitter and Flickr updates from one place - Learn more! <http://clk.atdmt.com/UKM/go/137984870/direct/01/> --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---