[geo] Global model study of sulfur injections by using commercial aircrafts
Hi all, Our paper Stratospheric passenger flights are likely an inefficient geoengineering strategy is now published in Environmental Research Letters: Laakso A., A.-I. Partanen, H. Kokkola, A. Laaksonen, K. E. J. Lehtinen and H. Korhonen (2012). Stratospheric passenger flights are likely an inefficient geoengineering strategy. Environ. Res. Lett. 7, 034021, doi:10.1088/1748-9326/7/3/034021 http://iopscience.iop.org/1748-9326/7/3/034021/ Abstract: Solar radiation management with stratospheric sulfur aerosols has been proposed as a potential geoengineering strategy to reduce global warming. However, there has been very little investigation on the efficiency of specific injection methods suggested. Here, we show that using stratospheric passenger flights to inject sulfate aerosols would not cause significant forcing under realistic injection scenarios: even if all present-day intercontinental flights were lifted above the tropopause, we simulate global surface shortwave radiative forcings of - 0.05 W m-2 and - 0.10 W m-2 with current and five times enhanced fuel sulfur concentrations, respectively. In the highly unlikely scenario that fuel sulfur content is enhanced by a factor of 50 (i.e. ten times the current legal limit) the radiative forcing is - 0.85 W m-2. This is significantly lower than if the same amount of sulfur were injected over the tropics ( - 1.32 W m-2, for 3 Tg (S) yr-1) due to a faster loss rate and lower intensity of solar radiation in the northern midlatitudes where current flight paths are concentrated. We also predict lower global forcing in northern hemisphere winter than in summer due to the seasonalities of the solar radiation intensity at midlatitudes, the related OH chemistry that produces sulfate aerosol, and removal of particles. Best regards, Anton Laakso -- 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.
[geo] corporate policy statements on geoengineering?
Is anyone aware of large corporations that have taken policy stands on geoengineering -- e.g. expressed support for the Oxford Principles, funded socially responsible research, joined coalitions, etc? -- 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.
RE: [geo] Coupled Model Intercomparison Project 5 (CMIP5) simulations of climate following volcanic eruptions
Dear all, the published version (no longer PiP) is now available here: http://www.agu.org/pubs/crossref/2012/2012JD017607.shtml Warm regards, Simon Simon Driscoll Atmospheric, Oceanic and Planetary Physics Department of Physics University of Oxford Office: 01865 272930 Mobile: 07935314940 http://www2.physics.ox.ac.uk/contacts/people/driscoll http://www.geoengineering.ox.ac.uk/people/who-are-we/simon-driscoll/ From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] on behalf of Andrew Lockley [andrew.lock...@gmail.com] Sent: 14 August 2012 02:06 To: geoengineering Subject: [geo] Coupled Model Intercomparison Project 5 (CMIP5) simulations of climate following volcanic eruptions http://www.agu.org/pubs/crossref/pip/2012JD017607.shtml The ability of the climate models submitted to the Coupled Model Intercomparison Project 5 (CMIP5) database to simulate the Northern Hemisphere winter climate following a large tropical volcanic eruption is assessed. When sulfate aerosols are produced by volcanic injections into the tropical stratosphere and spread by the stratospheric circulation, it not only causes globally averaged tropospheric cooling but also a localized heating in the lower stratosphere, which can cause major dynamical feedbacks. Observations show a lower stratospheric and surface response during the following one or two Northern Hemisphere (NH) winters, that resembles the positive phase of the North Atlantic Oscillation (NAO). Simulations from 13 CMIP5 models that represent tropical eruptions in the 19th and 20th century are examined, focusing on the large-scale regional impacts associated with the large-scale circulation during the NH winter season. The models generally fail to capture the NH dynamical response following eruptions. They do not sufficiently simulate the observed post-volcanic strengthened NH polar vortex, positive NAO, or NH Eurasian warming pattern, and they tend to overestimate the cooling in the tropical troposphere. The findings are confirmed by a superposed epoch analysis of the NAO index for each model. The study confirms previous similar evaluations and raises concern for the ability of current climate models to simulate the response of a major mode of global circulation variability to external forcings. This is also of concern for the accuracy of geoengineering modeling studies that assess the atmospheric response to stratosphere-injected particles.Received 13 February 2012; accepted 24 July 2012. -- 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. -- 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.
Re: [geo] Meanwhile, Arctic dullwater
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 r...@llnl.gov 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.
Re: [geo] Meanwhile, Arctic dullwater
I'm with you, John. Certainly one positive feedback is the 90 billion barrels of undiscovered, technically recoverable oil (and 44 billion barrels of natural gas liquids )* up there that are suddenly getting a whole lot easier to extract. Anyone care to calculate the watts of additional warming from this godsend to BAU? GEers saddle up. -Greg *http://en.wikipedia.org/wiki/Petroleum_exploration_in_the_Arctic From: John Nissen johnnissen2...@gmail.com To: r...@llnl.gov Cc: geoengineering geoengineering@googlegroups.com; John Nissen j...@cloudworld.co.uk; David Tattershall h...@invent2.com; P. Wadhams p...@cam.ac.uk Sent: Mon, September 10, 2012 3:16:00 PM Subject: Re: [geo] Meanwhile, Arctic dullwater 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 r...@llnl.gov 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
