It sounds in the video as though they're classifying ice as one-year (survived one summer), two-year (survived two summers), and multi-year (survived more than two summers). That terminology seems reasonable if explained, but it makes for a somewhat misleading headline.
On Jun 9, 3:46 am, Veli Albert Kallio <[email protected]> wrote: > I presume that John was referring to two-season ice, which is not usually > considered as multi year ice. Two year ice can be rather weak. > > What is important on Pen Hadlow's sea ice thickeness that 2,500 holes from > Canada to the North Pole produced an average thickeness of 177.4 cm. In my > experience ice of thickeness 120 cm will melt away by second week of July. > So the margin is 57.4 cm. > > There aren't lots of leeway as some of the ice fell below average and must be > closer to the tipping point. All those ice areas with only 120 cm will > definitely melt, perhaps those 150 cm. It all depends how good start the > melting gets. > > The sea ice on its last legs will behave very differently than ice that was > before. Wave penetration, reduced sea ice area all influence the vertical > mixing of sea water and make ice more motionary, mopping up heat when ice > encounters open (warmed) waters. > > The localised vertical mixing of sea water is also very dangerous for ice in > stormier conditions if there are open water and ice travelling with it. Ice > is propelled by wind providing a drag as well as higher windward water column > against the trough side. > > The higher watercolumn on the windward will produced pumping which raises > deep water up nearby. We'll see how things develop but the computer models > are as good as that keeping as flying models when unanticipated processes > kick in and are not put in the models. > > Please note that I have been constantly saying since 2005 that we might get > ice free ocean by end of decade due to a number of things, which I have > occasionally mentioned. > > I am worried about the methane coming from the warming soils, more intensive > decay, methane clathrates and the possibility (likelihood?) of strong and > swift coupling with marine and terrestrial ice losses in the Arctic (i.e. > Greenland ice sheet whole scale land containment failure developing shortly > in post-sea ice Arctic as expressed by HE President Morales in Poznan and > some other advocates). > > Regards, > > Albert > > Date: Mon, 8 Jun 2009 18:47:43 -0400 > Subject: [geo] Re: Arctic sea ice - no multi-year ice found > From: [email protected] > To: [email protected] > CC: [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected] > > John: > > Of course there is multi-year Arctic sea ice. You may want to take a look at > a fascinating display of Arctic sea ice photo's arranged as a movie video on > YouTube, available here, with explanation on what was done and how. > http://wattsupwiththat.com/2009/05/31/arctic-sea-ice-time-lapse-from-... > > This video shows a 31 year progression of freezing and melting over the pole. > When you get to last year and this year, you will see the summer conditions > show plenty of ice still in the Arctic sea and upon which still more snow has > fallen this year. That is not to say it couldn't all just plain disappear, > but at this point, it is incorrect to say that there is simply no multi-year > ice. Anyone who looked and didn't find it is simply looking in the wrong > place. > > David. > > On Mon, Jun 8, 2009 at 5:57 PM, John Nissen <[email protected]> wrote: > > It is now accepted by most scientists that the Arctic sea ice retreat is > caused by anthropogenic global warming, though the exact mechanism for the > "polar amplification" of global warming is not well understood. Critical for > sea ice survival is the multi-year ice. > > In his recent measurements of Arctic sea ice, Pen Hadow found absolutely no > multi-year ice, and the one-year ice was about 4 foot thick. This is > extremely disturbing, because the one-year ice can melt away very suddenly, > given warm weather. So when Vick Pope says that the sea ice could disappear > "later this century", it is a gross understatement of the danger. The Pen > Hadow finding shows that the sea ice could disappear quite suddenly, if the > natural variation in Arctic weather led to a much warmer than average summer, > such as in 2007 only more so. > > http://vodpod.com/watch/1634449-british-team-finds-no-multi-year-ice > > The implications are: > 1. The risk of massive methane outgassing is increased. > 2. The risk of Greenland ice sheet destabilisation is increased. > 3. Emissions reductions by end century will certainly be too late, even if > they were to have a cooling effect in the Arctic. > 4. Geoengineering in the Arctic must now be deployed for cooling the Arctic. > 5. The sooner it is deployed the better, providing it is done carefully to > reduce risk of adverse side-effects. > 6. Black carbon levels must also be reduced, as they help to melt snow and > ice in the Arctic. > > Now I know that Vicky Pope considers that this is being apocalyptic. But > actually it's all about risk management. The very argument she uses about > variability actually increases the risk that the sea ice disappears much > sooner than expected, as a violent swing on one side of the trend line. This > is what Vicky was writing in the Guardian in February this year: > > http://www.guardian.co.uk/environment/2009/feb/11/climate-change-misl... > > [quote] > Pope says there is little evidence to support claims that Arctic ice has > reached a tipping point and could disappear within a decade or so, as some > reports have suggested. Summer ice extent in the Arctic, formed by frozen sea > water, has collapsed in recent years, with ice extent in September last year > 34% lower than the average since satellite measurements began in 1979. > > "The record-breaking losses in the past couple of years could easily be due > to natural fluctuations in the weather, with summer ice increasing again over > the next few years," she says. > [end quote] > > The result of this optimistic view of sea ice survival, promoted by the IPCC > and continued by the Hadley centre, is that governments are blissfully > unaware of the risk of sea ice disappearance and repercussions. Furthermore, > they are still being led to believe that emissions reduction alone can halt > global warming before tipping points (such as sea ice disappearance) are > reached. This is absolute nonsense, since there is no way that emissions > reduction can cause a cooling effect in the Arctic. > > In the same article, Vicky Pope said "the implications of climate change are > profound and will be severe if greenhouse gas emissions are not cut > drastically" - but if governments focus on emissions reduction alone, there > is the danger of sea ice disappearance taking us all by surprise. And then > it will be too late. > > Cheers, > > John > > -- > David W. Schnare > Center for Environmental Stewardship > > _________________________________________________________________ > Get the best of MSN on your > mobilehttp://clk.atdmt.com/UKM/go/147991039/direct/01/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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