Robert S. Can you provide a reference to support your claim that solar panels do not return enough electricity to pay back manufacture in some grid conditions. It strikes me that if less power is drawn from the grid they will shut down the gas powered generators. They will keep generating hydro but can sell it to the Americans. According to that logic, until the grid is fully renewable adding solar will decrease emissions. And even then more solar means more hydro exported to displace fossil fuels in America. Solar panels anywhere generate electricity that displaces fossil fuel somewhere.

This is a free copy of Mueller et al: https://dspace.library.uvic.ca/bitstream/handle/1828/7669/Mueller_Bennit_MSc_2016.pdf?sequence=1 Google Scholar shows free copies listed to the right hand side. Neven, I rarely post here anymore but I read all the OP's and most of the comments. I think you do a great job of describing the main points of the melt season. If I want more detail I look at the forum. Keep up the good work!

This is a free copy of Mueller et al: https://dspace.library.uvic.ca/bitstream/handle/1828/7669/Mueller_Bennit_MSc_2016.pdf?sequence=1 Google Scholar shows free copies listed to the right hand side. Neven, I rarely post here anymore but I read all the OP's and most of the comments. I think you do a great job of describing the main points of the melt season. If I want more detail I look at the forum. Keep up the good work!

D-penguin, In your model it appears to me that you have left out the transport of CO2 into the deep ocean. This occurs in the Arctic and Antarctic when deep water forms. This is the primary long term storage of CO2 in the ocean. Since the deep water circulation takes 1-2,000 years, it will be 1-2,000 years before the ocean reaches a new equilibrium. This is discussed in the peer reviewed literature. How can you begin a discussion of ocean CO2 when you leave out the primary long term method of sequestration from the start? Where did you get your estimate of 10 years to a new equilibrium? Above two posters call referring to the peer reviewed literature "appealing to authority". This completely turns the scientific method on its head. The literature vets arguments and tries to remove errors. If you do not reference your arguments to vetted studies you will repeat errors long ago corrected in the peer reviewed literature. Since scientists argue both sides of most issues, the literature can be cited by both sides. Lack of reference to peer reviewed literature is the problem on "skeptical" sites. You have the same problem here if you do not reference the literature. Read Tom Curtis on Skeptical Science. Read Real Climate. The scientists on Real Climate always refer to the literature in any post they make, even though they are expert at what they write on. Amateurs need to provide a basis for their arguments. That lies in the peer reviewed literature. If you cannot find support for your argument in the literature that generally means that there is something incorrect in your argument. You are reinventing the wheel with your discussions of ocean sequestration of CO2. Read the peer reviewed literature.

DCS, You need to look up some peer reviewed papers. When you do you will see that Rob Decker is completely correct and your logic is completely incorrect. The absorption of CO2 into the ocean is proportional to the atmospheric concentration of CO2, not the emission rate. If emissions were cut in half today for the next few years the absorption by the ocean would be the same as it is now, not half current absorption. Over long periods it is more complicated. This: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0081648&type=printable Hansen paper discusses the response of the global carbon cycle when emissions are reduced. It only discusses ocean absorption a little. This https://scripps.ucsd.edu/programs/keelingcurve/2013/07/03/how-much-co2-can-the-oceans-take-up/ Scripps article describes how most of the carbon absorbed into the ocean will eventually end up in the deep ocean. Warming of the surface layer slows transfer of CO2 to the deep ocean. Several of the current prolific posters on this blog never reference peer reviewed papers and just speculate on what seems correct to their uninformed minds. You are wasting everyone else's time. Please provide peer reviewed data to support your conclusions. Unsupported internet ramblings do not lead to constructive discussions. If you cannot find peer reviewed papers that support your conclusions perhaps you need to consider if your logic has a flaw.

Nielt and D, As referenced in Jacobson 2009, the best path forward is the cheapest, fastest at the time. That is wind, water and solar (WWS). It would be a waste of money to put significant resources into a solar shield. Your assertions that everything must be done at the same time do not withstand close evaluation. Neither of you has cited any peer reviewed resource to cost out your proposals. With no cost projections the cost has to be presumed to be too high. Jacobson has several papers online at the Solutions Project that detail the costs of his plans using WWS to power the world. Speculation that the cost of putting material into orbit can be decreased by two orders of magnitude (!??!) are not data. Skeptics point to wild proposals like the ones discussed here for a solar shield to make all climate scientists look bad. You are hurting the cause of trying to do something about AGW. If you cannot find a peer reviewed study to support your wild claims about a solar shield you should take that to mean that it is impractical. Unsupported internet postings do not count. This argument has gone in circles for most of the time. Nothing new has been posted recently. I will not post again until the supporters of this impractical scheme provide peer reviewed references to support their wild claims about solar shields. If all emissions were to stop today, the ocean would continue to absorb CO2 and the atmospheric concentration might begin to go down. It is not clear yet if the release of CO2 from natural sources would be more important than the sink of CO2 into the ocean. Hansen has commented on this extensively in his writings. The 350.org people rely on this mechanism to get CO2 back down to 350 ppm. Since you do not provide references I will not also. Google it.

Reviewing Jacobson 2008 https://web.stanford.edu/group/efmh/jacobson/Articles/I/ReviewSolGW09.pdf, the key factor to consider in comparison of solar PV to solar shading is figure 3. This figure calculates the amount of CO2 emitted because of delays in installation of the fastest technology. Solar and wind are the fastest technologies to install. Since a new method of reaching orbit has to be developed first to reduce launching costs by a factor of at least 100, it would be decades before a system of solar shading could be built. Solar and wind can be built immediately. Delaying the installation of wind and solar to develop a solar shade would result in more CO2 being emitted. Jacobson does not consider cost in his evaluation of different technologies in this paper.

D, The most effective way to address a problem is to invest first in the cheapest method of reducing the problem. If you invest in solar dimming when it is much cheaper to build out solar panels you end up with a lot more carbon in the atmosphere. Since the goal is to reduce carbon in the atmosphere you have to invest in WWS first. Read jacobson 2009 http://pubs.rsc.org/en/content/articlelanding/2009/ee/b809990c/unauth#!divAbstract. He gives the argument that Nuclear is not worth investing in because it is too expensive. (I note that geoengineering solutions are not even evaluated in this paper because they are too speculative). Geoengineering like you suggest is just 10 times more off base. Your argument that we must pursue all avenues at the same time is simply incorrect. The best way forward is to pursue the cheapest path for the most benefit. Your claims about the benefits of a solar shield appear to me to come from blog posts you have found on the internet. Find peer reviewed studies that sopport your wild claims about the benefits of a solar shield. Please provide an estimate of the cost for your completely speculative suggestion of a lunar base to build the shield from. We currently have difficulty convincing people to build out wind, water and solar which will supply us with cheaper, usable power without pollution. Suggest two reasons you think the population would shell out the trillions needed just to begin to build the lunar base. Keep in mind that this money is just a hole in the ground where no immediate benefit is apparent. You have not addressed the problems with your proposed "solution" relating to ocean acidification, drought and people thinking they can burn more fossil fuels because the shield will protect them from the problem. Ignoring major flaws in your argument does not make it stronger. I think your claims make people much less willing to listen to proposals to work on actual solutions to AGW. There is no chance your suggestions will be acted on. You claim WWS cannot resolve the problem without apparent peer reviewed data to support your claim. Please cite some peer reviewed papers to support your wild claims. I note that Jacobson 2009, linked above, has hundreds of citations that suggest WWS can substantially address the problem.

NielT, To have the greatest effect we have to implement the lowest cost methods first. It is a waste of money to put up a solar shield if solar panels are cheaper to reduce carbon pollution. Every dollar for a solar shield could have installed at least 4x as much mitigation by solar panels. Your claim that a solar shield would last forever without maintenance is incorrect. The orbits are not stable for anywhere near that long and something built so thin cannot withstand the solar wind for decades. Manufacturing the shield on the moon is absurd. The cost of building a moon manufacturing plant would exceed the cost of solar power with storage for the entire world. Ocean acidification is unaffected and worldwide drought is enhanced. I do not see you citing peer reviewed articles supporting your claims. Hundreds of peer reviewed studies support using wind, water and solar power to provide all power in the world. See Jacobson 2015 and the cited references. People who make these type of wild claims make it more difficult to convince the public that action really has to be taken about AGW.

Tamino's stuff is always on the mark. These posts are a good way to keep the blog going over the freezing season. Winnipus's (sp?) graph of global sea ice extent would be unbelievable if it were not the actual data. Not even the most alarmist poster on this board would have guessed the ice would go so low so soon.

Even without seeing Rob's calculation of the mitigation effect of a PV panel, I can state without question that the PV panel produces useful electricity while the solar shield is useless expense. Estimates of a Trillion dollars to put 1E12 meters squared of solar shield in orbit are grossly too low. Proponents suggest they can lower the cost of space flight by factors of 100 or more to get into the game. If this was in the newspaper it would be fake news. Proponents of space activity have been claiming since I was a child (I am 57) that their scheme will lower costs by huge factors. Meanwhile it costs about the same to launch into orbit as it did 50 years ago. Current cost to put material in GTO is $27,000/kg. If Robs' 1m2 solar shield weighed 1 gram it would cost $27 to put in orbit. About $5 per tank of gas. It is invariable that proponents of geoengineering do not think their proposals through. If you do they rapidly fall apart.

Hans, this reference: http://www.climatecentral.org/news/geoengineering-could-cut-global-rainfall-study-finds-16699 summarizes a study that shows that solar shades will reduce rainfall worldwide. This is projected to cause the east Asian monsoon to fail. Perhaps a geoengineered solar shade would be bad for many people. You must consider all the consequences before you plan to deploy geoengineering for the entire globe. Would you volunteer your part of the globe for permanent severe drought to help out the people who put all the carbon in the air?

Hans,

Snow will not remain frozen if it falls into -1C sea water at 1.035. The melting point of the ice is determined by the equilibrium of the ice water mix, not by the purity of the water in the ice. If someone says that snow remains frozen in warmer water they need to review their basic chemistry. How do you explain salt removing the ice from roads in winter? The surface water may be less salty, but ice cannot survive in water warmer than the equilibrium (freezing) temperature. If you claim that the water is less salty you have to explain why the surface is not mixing well this year with all the storms and waves. What is different from last year? If the surface adds 10-20 cm of ice it is freezing. Why is that different from normal? Your argument contradicts itself. Do you have data to support your claim that the surface is much less salty than it was last year? I make ice cream all the time by adding salt to fresh water ice at 0C. The temperature goes down as the salt dissolves until it reaches equilibrium.

The Northwest passage is still open through the Fury and Hecla strait Canadian Ice Chart. It will probably be closed later this week. This was the first year that route was open. I doubt anyone is still trying to get through so late in the season. Claims at WUWT that the passage is closed are incorrect. Jim Hunt has followed this much closer than I did. Do you know how many yachts made the passage this year?

Jim, Looking at the Canada Sea Ice graph for the Queen Maude strait, it appears that ice blocks the passage north. It would be possible to go through the Fury and Hecla strait into the Foxe Basin. I think this is the first year that the Fury and Hecla strait has been open, but it may have been open in 2012. It looks to me like it will be open through Foxe basin for about another week.

At RealClimate they have an arctic sea ice link at the start of the new monthly thread that links to this blog! I rarely post but I read all the posts on the blog. I especially appreciate the OP's by Neven. They are more even handed than many of the posts by others. It is remarkable how Neven has informed himself about the science. As Neven often points out, the Arctic sea ice has many surprises that we will not anticipate. Last year was low melt but this year is going low at the end. How much longer will it go lower?

Bobcobb, From your reference in the New York Times magazine: "When I asked Richard Alley, almost certainly the most respected glaciologist in the United States, whether he would be surprised to see Thwaites collapse in his lifetime, he drew a breath. Alley is 58. ‘‘Up until very recently, I would have said, ‘Yes, I’d be surprised,’ ’’ he told me. ‘‘Right now, I’m not sure. I’m still cautiously optimistic that in my life, Thwaites has got enough stability on the ridge where it now sits that I will die before it does. But I’m not confident about that for my kids. " Richard Alley is the same age I am. He cannot possibly live much past 2050. He states that he thinks it is possible Thwaites could collapse in his lifetime. That would be meters of sea level rise in his lifetime. He thinks that is unlikely, but possible. He agrees with Hansen. In the same article Rignot agrees with Hansen. You need to let this go, your references contradict what you claim.

The Queen Maud area of the North West Passage has melted dramatically in the past two or three days. See Canada Sea Ice Graphs. Last week I thought it would not clear this year and now it looks like it will clear enough for the yachts waiting there to make it through.

Pete, I think the mass balance data you linked does not include melting of the ice sheet from contact with the ocean. Mass balance data is only the surface accumulation of snow and melting of snow and ice. Icebergs and bottom melt are also a big loss of ice from Greenland.

Even the southern route of the North West Passage has been choked with ice this year. Several of the boats that made it through had ice breaker assistance. They also passed through open ice fields with 20% or more ice. The Canadian Ice Service only rates the NWP as open when there is a passage with no ice. It appears unlikely that that will happen even on the southerly route this year as ice has moved over the passage at both ends near Resolute and the Amundson Gulf. You have to look at the Canadian Ice Service maps to see the details of ice in the passage, the satellite images miss a lot of ice.

I guess 4.0 Mkm2. It has been so cloudy and cold that I have to raise my guess. I think there will be a lot of melt in August, but not enough to catch 2012.

Dorlomin, Sorry for the slow response. I was out of town. You cite a paper that is ten years old to support your claim that it was warmer previously in the Holocene than it is now. It precedes the melting of the Arctic ice shelves and the collapse of Arctic sea ice. The Arctic temperature has increased substantially in the last decade. It is behind a paywall so I cannot determine how much warmer they claim it was ten years ago. Can you produce an up to date cite to support your claim that the Holocene was warmer in the Arctic? The global heat budget is substantially larger than it has been at any time in the Holocene. While the Arctic insolation was larger in the past, much more heat is being transported into the Arctic from the Atlantic ocean than at any other time. The global temperature already has substantial warming in the pipeline. Greenland has seen only a few melting days over its entire surface like last years. Your claim that the Holocene was warmer needs more data to support it.

The Nares ice arch collapsed today. It is clearly visible on AtcticIo from the sea ice graphs page (day 7-23).

It seems to me that it has been much cloudier this year than the last few years. Has anyone seen a post quantitating the amount of clouds this year compared to previous years?