Hi all, Thanks Greg. It is astonishing that the Met Office is still sticking to outdated models, though they have been gradually bringing forward their predictions of sea ice demise down since the IPCC prediction of 'beyond 2100' in AR4.
Peter Wadhams has been predicting that sea ice volume will follow the PIOMAS exponential trend, towards a seasonally ice free Arctic by 2015, see www.ameg.me. This summer's record low shows that the trend is being followed. Note also that the PIOMAS trend curves for different months, shows that we could have six months sea ice free by 2020. What do we do about it? Do we do nothing, and accept the consequences, however dire (and Hansen supports AMEG claim that they could be fatal for civilisation, if there is a big methane release from clathrates as protective ice cover is removed) - or do we fight to cool the Arctic and restore the sea ice? By back-of-envelope calculation: if geoengineering techniques can provide cooling power enough to counter a doubling of CO2, which would be of the order of a petawatt, then that should be sufficient to cool the Arctic, if positive feedbacks don't get much worse. So we must not be defeatist about the situation, however dire the consequences of sea ice disappearance. But we need the help of the whole geoengineering and modelling communities to work together on a solution for extremely rapid cooling, starting next spring if at all possible. Please let me know if you would like to help. Cheers, John --- On Thu, Sep 6, 2012 at 7:59 PM, Rau, Greg <[email protected]> wrote: > Arctic ice melt 'like adding 20 years of CO2 emissions' > http://www.bbc.co.uk/news/science-environment-19496674 > > By Susan Watts > Newsnight Science editor, BBC News > The loss of Arctic ice is massively compounding the effects of greenhouse > gas emissions, ice scientist Professor Peter Wadhams has told BBC Newsnight. > White ice reflects more sunlight than open water, acting like a parasol. > Melting of white Arctic ice, currently at its lowest level in recent > history, is causing more absorption. > Prof Wadhams calculates this absorption of the sun's rays is having an > effect "the equivalent of about 20 years of additional CO2 being added by > man". > The Cambridge University expert says that the Arctic ice cap is "heading > for oblivion". > In 1980, the Arctic ice in summer made up some 2% of the Earth's surface. > But since then the ice has roughly halved in area. > "Thirty years ago there was typically about eight million square > kilometres of ice left in the Arctic in the summer, and by 2007 that had > halved, it had gone down to about four million, and this year it has gone > down below that," Prof Wadhams said. > And the volume of ice has dropped, with the ice getting thinner: > "The volume of ice in the summer is only a quarter of what it was 30 years > ago and that's really the prelude to this final collapse," Prof Wadhams > said. > Parts of the Arctic Ocean are now as warm in summer as the North Sea is in > winter, Prof Wadhams said. > Radiation absorbed > The polar ice cap acts as a giant parasol, reflecting sunlight back into > the atmosphere in what is known as the albedo effect. > But white ice and snow reflect far more of the sun's energy than the open > water that is replacing it as the ice melts. > Instead of being reflected away from the Earth, this energy is absorbed, > and contributes to warming: > "Over that 1% of the Earth's surface you are replacing a bright surface > which reflects nearly all of the radiation falling on it with a dark > surface which absorbs nearly all. > "The difference, the extra radiation that's absorbed is, from our > calculations, the equivalent of about 20 years of additional CO2 being > added by man," Prof Wadhams said. > If his calculations are correct then that means that over recent decades > the melting of the Arctic ice cap has put as much heat into the system as > all the CO2 we have generated in that time. > And if the ice continues to decline at the current rate it could play an > even bigger role than greenhouse gases. > UK weather effect > Professor Wadhams stresses that there are uncertainties - cloud cover over > the Arctic could change and help reflect back some of the sun's radiation. > But then another greenhouse gas - methane, currently trapped in the Arctic > permafrost - could be released with warming and make matters worse. > The melting ice could have knock-on effects in the UK. Adam Scaife, from > the Met Office Hadley Centre told Newsnight it could help explain this > year's miserable wet summer, by altering the course of the jet stream. > "Some studies suggest that there is increased risk of wet, low pressure > summers over the UK as the ice melts." > There may be an effect for our winters too: "Winter weather could become > more easterly cold and snowy as the ice declines," Mr Scaife said. > Opinions vary on the date of the demise of summer sea ice. The Met Office > says it is not expecting the Arctic to be completely ice-free in summer > until after 2030. > > -- > 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. > > -- 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.
