But it isn't neck and neck. I just looked at the daily data... If you compare the last 7 days of data available (as of this posting), you see the following: 2019, day 174, 13,890 km3 2019, day 181, 12,047 km3. 2019 7 day melt estimate: 1,843 km3 2012, day 174, 13,897 km3, 2012, day 181, 12,295 km3, 2012 7 day melt estimate: 1,602 km3. 2019 has seen a rate of ~34.4 km3/day faster melt-off than that seen in 2012 over the past week. That's not neck-and-neck... that's pacing 15% faster melt rate.

gkoehler, Susan Anderson; I'm happy that I could contribute. I've lurked here for years, just attempting to learn. I'm passionate about climate change, but the cryosphere was such an alien world when I first took interest that it was nice to find a forum where people of significant knowledge gathered and discussed this seemingly unknowable world without many trolls or tangents (Neven really has given us all a wonderful resource here)... and I've learned a lot. It's nice to give back when I can, and while the cryosphere is still more foreign to me than many regions... I spend my days as an engineer, so the geometry stands out for me. :) That was a question I could answer. Kevin McKinney, thanks for the link.

gkoehler As to your first point, regarding counter-intuitive earlier minimum extent... that isn't so counter-intuitive if you think about it mathematically. The minimum extent has contracted - considerably - compared to the 80's, 90's, and 00's. So you have a smaller radius, closer to 90 degrees north. When the sun begins to set at the top of the world, the temperature at the pole gets cold again, even as the warmer September waters continue to eat away at the edges of the icepack which are still in the sun. But as the radius gets smaller, the point at which the sun sets on the edges of the icepack gets earlier, cooling the water attacking the edges of the pack while the center refreezes and begins its slow re-expansion. As long as the extent continues to contract, you'll see the minimum continue to happen earlier.

The correct figures, of course, are ~315 W/m2 at 273 K and 188 W/m2 at 240 K. (I am quite distracted when I chime in here, and I probably should just continue to lurk). But again, of course, this is what would be expected from an ideal black body. From water, a grey body which absorbs many spectra of microwave and infrared, the actual energy flux emitted would be far less. Though I don't know what the emission would be. The easiest way to solve the problem would be to find a Top-of-atmosphere reading or calculation of outgoing energy flux at the arctic. Then we reduce the issue to just albedo change and surface area. I don't suppose anyone has a handy map of TOA outgoing flux or energy flux balance? I like this one from NASA, but I can't change the color range, and to look at the arctic you'd need a tighter color range. http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_NETFLUX_M&year=2016

Wayne, You are calculating total insolation, but what is not factored in is the energy re-radiated from the surface. You have to have that in order to get the amplification/forcing. I can accept Rob's model results without embellishment: climate models are estimating ~90 W/m2 average yearlong insolation is radiating the arctic surface. If you factor that for the arctic ocean, you would get ~11 EWh of total incoming radiant energy. It takes ~92 TWh to melt a km3 of ice... So the total radiant energy striking the arctic could - in a perfect blackbody, in a perfectly shielded experiment - melt ~119.565 km3 of ice. Then we start playing games with albedo. If you assume 50% albedo, you halve that figure. If you assume 80%, it gets down towards the numbers you were stating... etc. But what you are not taking into account is the energy that is radiating from the Earth/atmosphere. It's cold in the arctic, but it's not absolute zero. Some energy is being constantly radiated out in microwave and longer-wavelength infrared. At 273 K, there would be roughly ~55 W/m energy flux radiated out from the arctic (minus atmospheric reflection). At 240 K that energy flux would be reduced to ~33 W/m. So that reduces the top-line insolation in the same manner that albedo does, and it starts messing with the total amount of energy that the arctic actually absorbs. I feel - therefore - it's easier to assume very little change in temperature (especially during the summer), and focus on the difference in insolation seen as the ice and snow melt. The system itself will shed most of the energy flux that it absorbs over the year from the normal frozen state that the arctic has seen over the past few million years.

zebra, A response to this: "So, where is the great accumulation of all the stored energy you are talking about?" The disappearance of >300 km3 of ice per year over the past ~38 years shows exactly that accumulation of energy. In truth, the long term average isn't nearly as instructive as the more recent average, which is nearly twice that. But right now we're just witnessing (mostly) the phase change of floating ice. Once the floating ice is no longer available to absorb that energy, then the energy must manifest in a different way. That's the scary part. Rather than the blue ocean absorbing more energy and having that energy be immediately transferred into phase change, if there is no floating ice to soak up that energy... what then? The radiation losses will not significantly increase in the winter because the surface WILL re-freeze, even if the warmer water below will keep the ice sheet thin.. I don't believe there will be anywhere near a commensurate increase in radiative losses, because the thin ice in the winter will keep conductive losses too low to heat the surface and atmosphere to such an extent that the total radiated energy can balance. As soon as this tremendous amount of energy influx can no longer be transferred into melting floating ice, it will have to be transferred somewhere else. That is the tipping point that I see. We are seeing the greater energy absorption and have been for years, but so far the vast majority of the energy imbalance has gone towards melting the icepack. When the icepack is gone..? It seems most likely to me that some portion of that energy will be directed to the underwater portions of the Greenland Ice Shelf, and some portion of that energy will continue to reduce the thickness of the ice - which will further worsen the next year's amplification...

@ Zebra, I got the terminology from Bill. As stated, I've been lurking here for some time, and I think that the term "albedo amplification" succinctly describes what I see as the scariest feedback mechanism. @ Rob Dekker, Thank you. When Neven first posted this article, I immediately thought "we're going to have blue ocean at north pole this year". I still think that the basic energy flows should result in most of the additional energy being trapped in the arctic until it is absorbed by melting ice. And I still hope that someone might be able to explain why my assumption is wrong on that... But at least the net energy would be far less than I was thinking. :)

John Bilsky, That is a fair rebuke. I apologize, to zebra and this forum.

zebra, Attempting to mock me for mistyping a number into the calculator doesn't make your position any more firm nor make my position any less so. I did not (and do not) mistake power and energy. There was no mistake between insolation and absorption. Please do not belittle a comment because of a typo in the calculator entry so that you can dismiss it without consideration. I will henceforth double-check my quick calculations before posting in this forum (which - to my chagrin - doesn't allow editing). Your concern for the internal system flows causes me to remain concerned that you are indeed missing the system at large. The "structure" of the system flows cannot change the fact that there are only three major pathways by which the heat can be removed from the arctic: radiation into space, "sunk" into the deeper ocean waters, and absorbed by the phase change of melting ice. The rate at which this energy is radiated into space will not increase quickly without a subsequent increase in surface/atmosphere temperature. Very soon after nightfall in the arctic the atmospheric temp drops sufficiently to sharply reduce evaporation losses to the atmosphere. A reasonably thin layer of ice would sharply reduce conductive losses to the atmosphere... So the winter shouldn't see a massive increase in total radiation losses that would correlate to the added energy absorption from amplification throughout the summer. The action of sinking water into the depths, from what I understand, is a result of brine rejection in the formation of the ice, the brine being heavy and carrying some of the heat from the surface layers down with it... But as the ice thins, this avenue seems likely to decrease, and the energy absorbed by the upper ~5-20 meters of ocean is likely to stay there. That leaves the final avenue - melting ice, or preventing ice formation. Big picture, the amplification effects from the disappearance of the arctic icepack are terrifying.. because there's not likely to be any place for the energy to go unless the temperature warms considerably or unless the warmer water swirls around Greenland and is cooled by melting that ice. Don't just dismiss this by saying "you have to nail down the first approximations". Please explain what I fail to understand, or at least attempt to point me in the right direction. I'm not asking to be ignored and belittled, I'm coming here in full recognition that I understand the physics and chemistry perfectly well, but understand the cryosphere far less than most other people posting here, and I wish to understand more. (And please don't just wave your hand and dismiss my post by saying I somehow mistook amplification, insolation, and absorption... I wouldn't have done such a thing since my early college years, and indeed did not do that here.)

Bah! I shouldn't type things out so quickly without checking numbers. :) A single hour would only result in additional amplification of ~1.5 PWh - assuming my shot-in-the-dark guess of ~200 W/m2 was about right. Oh well. Rambling quickly is how I typically blog, which is why I tend to lurk instead. ;)

Zebra, I've been away a few days, and the conversation has kind of wandered a little from where we left off. :) But I wanted to get back to it for a second. When you said this: "Are you talking about three days below the "ice-free" threshold, or three weeks, or three months?" I am concerned that you might be "missing the forest for the trees". I'm not talking about 3 days or 3 weeks. I'm talking about 3 seconds. Right now, the continual additional heating from blue ocean amplification is going towards melting sea ice. So as weather has fluctuated year-by-year, we've seen an average of ~300 km3 of ice disappear from the arctic cap/year. That level of energy absorption works out to only ~28 PWh. That really doesn't SEEM like that much net increase for the arctic system... it's about 7 times the total electrical energy generated in America in a year. But that number is so small (!!!) only because of the short time duration that significant amplification is experienced, since most of the area is restored every year during the winter. The actual power from potential amplification is insane. A blue ocean event would drop the area to below 1 million km2. This from the former average low of >4.5 million. If you assume only ~200 W/m2 insolation during September (a shot in the dark on my part, I couldn't find it through a quick google search), then a single hour of blue ocean at 90 degrees N would result in over 4 PWh of energy injected into the waters of the arctic. As that cycles around, some portion of that energy - enough to melt ~43 km3 of ice - will be transferred to the underwater support of the glaciers of the Greenland Ice Sheet. That's ONE HOUR. A single day of such amplification would result in (considerably) more melting of Greenland ice than is currently averaged all year. Of course, 100% of it wouldn't be transferred to Greenland, much of it would just be retained in the form of far warmer water, which would more rapidly degrade ice thickness. This tipping point is so massive that after literally years of trying to wrap my head around the scope of it I have continually failed. It's terrifying. It is a complete paradigm shift. And it's possibly going to happen this year.

Zebra, It's true that there would be more evaporation, and hence some transfer of of energy from the sea surface to the upper atmosphere... But there's no way the scales should balance. At ~3 C, the vapor pressure of water is still only 752 Pa.. so it's not like there will be a massive boil-off of the ocean. I cannot but believe that the amplification impact of reducing albedo from 0.8 - ~0.1 would far overshadow the energy loss from evaporation (more than half of which would be returned). The presence of higher water vapor content in the Arctic atmosphere would then add more greenhouse forcing, and could lead to net higher pressure for the region keeping the skies clear in the summer. I also cannot imagine how the possibility of increased snowfall in Greenland could outpace the increased melt-rate caused by waters that would absorb additional energy in the multiple EWh scale.. The increased attack on the foundation of the Greenland Ice shelf would lead to calving of ice masses that tower hundreds or even thousands of feet above the ocean. What is a few additional feet of snowfall going to do to compete with that? Obviously, we don't know all things, and I know far less than many. I understand the physics well and the basic feedback mechanisms involved in climate change at large... and I'm struggling to understand the cryosphere - which I imagine most of the contributors here know far more than I. But I cannot see any feedback mechanism within the cryosphere that can outpace the amplification caused by albedo loss from the disappearance of the ice. The vast majority of feedback mechanisms that I see in that area would only serve to further amplify warming even still. I've lurked for quite some time, and am only now starting to post to seek answers for what I don't understand... So I'll welcome any additional knowledge or perspective and I don't claim expertise. But I cannot see how the items you listed will significantly slow the runaway spiral.

Bill's reply correctly interpreted the intent of my comment. :) I would only add that the uncertainty of the area estimate is not as problematic - in terms of considering amplification effects - as is assumed. Melt ponds also have significantly lower albedo than ice or snow-covered ice, which is why the satellites sometimes get confused and assume melt ponds are open water. If the concern is amplification, the overall error in area estimates probably serves to present a more accurate representation of the amplification concern. Everything is an estimate, everything carries some degree of uncertainty... but we know that a world in which there is 2,000,000 km2 less area covered by ice in the arctic would result in far more heat absorption by the arctic ocean, which would impact the amount of heat flowing around the base of the Greenland Ice Sheet... If the actual fact of the matter is that there is merely 1.8 million km2 less area of ice and an additional 0.2 million km2 of melt ponds, the total amount of additional energy injected into the arctic water will be similar, and it will still be terrifying.

I had meant to say "your denialist is partly right".. I'm trying to maintain discipline and not give the denialist nonsense-engines any other label than "denialist". A skeptic is one who demands evidence before believing... the idiots railing against climate change are people who reject and ignore evidence in order to cling to denial against any and all facts and logic.

Joshua, Your skeptic is partly right... the thing everyone is scared about is the amplification effects caused by losing the big mirror... so the metric that would be of greatest immediate impact would be Arctic sea ice AREA (extent is meaningless) during the melting season... But the status of the icepack during the winter and early spring should have a pretty big impact on the average sea ice area that is seen over the course of the melting season. Your denialist is trying to pretend that the two metrics: status of the icepack during the winter and status of the icepack during the summer; can be treated as entirely separate cases, which is absurd. If we're down ~2000 km3 now, it's hard to imagine how we'll not see a significantly lower area as this much smaller volume of ice melts away during the melting season.

Bill, I would be shocked if the residual ice left at 90 degrees N in September would be a challenge for the average breaker. I expect a few hours of blue water... If so, it's no longer a question of "if" a breaker tests that passage, it's "how early". But with respect to global emissions. I thought (I could be wrong here, obviously) that when they said "36 GT-CO2", they meant "36 GT-CO2e". I thought that number included tens of millions of tons of methane and hundreds of millions of tons of NOx and tens of thousands of tons of CFC's and other refrigerants and industrial solvents and hundreds of thousands of tons of carbon black... etc.. I thought in terms of actual CO2, we were only emitting ~20-25 GT/year. The "tons CO2e" was simply an easier way to digest the information... and the media just simplified it further to "tons CO2". I haven't really looked into it, it's been my general understanding of how the numbers are read for as long as I can remember. But if I'm wrong in this, than in my attempts to reconcile and grasp the scope of the issue, I've been low-balling the scope of the issue considerably. (!!!!), and I'm pretty horrified by the scope of the issue now.

D-Penguin, Bill's post involved two different units: GT-C, and GT-CO2. He quoted a source saying that "another 1000 GT-CO2 would lead to ice-free arctic in Sept". And then he went on to note that our current emissions are ~10 GT-C. 10 GT-C is 36.7 GT-CO2. (also, these numbers are likely "GT-CO2e", meaning that the total global warming potential of all emissions would equal the equivalent of X GT-CO2. When people shorten that to GT-C, they take the unit of GT-CO2e and divide by 3.666666666). :) That said. I think we'll see a blue ocean at 90 degrees N for a few hours of this year... though it may be several years before that becomes the norm. 2043 was a fantasy of yesteryear. We've crossed a tipping point, and this is worse than projected.

Thanks Kevin, and Rob. I would only add that the albedo amplification should be significantly greater this year than in years past... so it seems quite plausible that this could herald a new record decrease as well... But it does put my mind a little more at ease. :) And yes, I do recognize that a 1400km3 total would be horrible... Though I lack the sophisticated knowledge of the cryosphere to imagine exactly what that would entail... I know more than enough physics and enough about the Greenland Ice Sheet for that alone to scare the crap out of me. It's like watching a tsunami approach in slow motion.

Rob Dekker, There's absolutely no reason to think that the current 2000 km3 lower ice volume in January will result in only ~2000 km3 lower ice volume in September. I cannot help but think about the difference this will make in terms of absorbed solar energy. With very thin ice at the edge of the pack, much of that should begin melting off as the sun rises, so millions of km2 of additional ocean surface will be absorbing 90+% of the insolation rather than ~20-30%. To make matters worse, large surface areas that are usually ice-covered will be far enough removed from the smaller edge of the ice pack that the absorbed energy could significantly warm the surface temperature rather than being mostly absorbed by phase change of nearby ice. Every ~1 C of surface temp warming will increase the vapor pressure of H2O by ~5%. So there are two strong feedback/amplification effects that will be occurring in any area of the arctic that melts off early, and that amplification will last the entire summer. I think it will take some extraordinary good luck with weather in order to only see September minimums remain 2000 km3 below recent norms. I know from lurking here for many years you know all this... So I just want to understand what I'm missing. What is your reasoning for what I see as incredible optimism in your comment, when you seem to speculate on September minimums being halved as a severe potential negative? It seems to me that would be about as good as we could hope for.

Wayne, That is what I suspected. :) Do you feel that we should anticipate a continued greater divergence from the norm - due to the continual venting of heat and moisture from the leads and open waters at the edge... or do you think there will be some convergence towards the mean in the next three months? You say that the high pressure systems quickly dissolve... Is there any way to anticipate a change in that trend, any signal from the weather patterns that might herald a shift, or is this just a wait-and-see issue?

I'm not an expert in weather, nor do I know that much about weather patterns in the cryosphere... But I cannot imagine how a cold front could be capable of making up sea ice formation at the rate of thousands of km3 faster than normal in only a few months. There is a limit to how cold the region can get, and with so much open water it seems like that lower limit will be elevated due to higher moisture levels. Is it really possible for that kind of deficit to be made up, or are we certain to start the melt period at a record low at this point? If we're certain to start the melt season with ~million km2 more dark water rather than white ice, that would mean the waters would be absorbing an extra ~EWh of energy over the summer (!!!!!!!!). How is this not a tipping point, a permanent redraw of the maximum extent of the ice cap? Am I underestimating the potential for the growth in ice volume over the next few months, or is this a far bigger deal than what the world has so far made it out to be?

Neven, I agree with you in terms of a kind of cap on inequality, but that would be very hard to define in terms of fixed nominal wealth in a world of fiat currency. ;) It would be easier just to struggle to achieve more progressive taxation, and the inequality would take care of itself and eventually become impossible past a certain degree. But while inequality MUST be examined on one end of the spectrum, the other and more critical end of the spectrum lies in population. That has to be looked at as well, and in fact controlling population would be the easiest means of controlling inequality. If the planet had 10 billion people living the lifestyle that is enjoyed by the median American household, it would require something along the lines of ~10 times our current global consumption... We aren't venturing into the lifestyles of the upper 0.1%, just the median American... and it's too much to contemplate for a population of 10 billion. In fact, the median lifestyle of a person in Europe would be far too great to imagine for 10 billion people. So the population portion of the equation must also be examined, as of course must efficiency - in both energy and other forms of consumption... and of course as much renewable and nuclear energy as we can build out as quickly as possible.

First of all, you don't necessarily NEED geoengineering to counter CO2 forcing. You need to reduce continued emissions, and you need time. So the question then becomes one of: "how much do we need to reduce emissions before we begin seeing the net concentration of GHG's in the atmosphere drop?" The answer to that, near as I can tell, is ~20 GT-CO2e (20 gigatons of CO2 equivalent). If we can get the global emissions down to 15-20 GT-CO2e or lower, then natural sinks will begin very gradually reducing the concentration of CO2 in the atmosphere. Obviously, the lower the better, since the natural sinks are reducing CO2 by ~15-20 GT/year, then we'd see concentrations reduce far more quickly by emitting 7 GT than we'd see if we were emitting 14 GT. The second consideration then is feedback mechanisms and convergence to system balance. It will take at least 50-100 years of continued warming and sea-level rise for the system to stop warming after we stabilize the concentration of GHG's in the atmosphere... for reasons I imagine that most here understand. So any question of geoengineering must then prove to be more cost effective than simply accommodating the projected warming from bringing a stable concentration into balance. (It's completely worthless to consider geoengineering until atmospheric concentrations are balanced). The problem is cost, and the cost of geoengineering is extraordinarily high. The only geoengineering solution that I've seen that isn't farcical upfront is one of putting high pressure water jets facing one another to smash the water into extremely small particles, which would then be buoyed up into the stratosphere for high altitude cloud formation (forced shading). This in and of itself would still be absurd in terms of cost... but taking it a step further you come up with an interesting concept: Imagine lining the coast of several of the Canadian islands East of Greenland with desalination plants and massive water jet arrays, powered by nuclear power plants. The (thousands of) arrays could then be used to produce high altitude clouds that would be blown over the Greenland Ice Sheet and some of the arctic ice cap. These clouds would provide shading and cooling during the summer and snow and mass building during the winter, and could be calibrated to balance the total global sea level rise... so the costs of building and maintaining the arrays would then mitigate the cost of rising seas (sea walls, storm damage, land area loss to salt marshes, etc..) But that is the type of thinking that will be required. What are the cost considerations of something on the scale of geoengineering, and what are the costs of just accommodating to the climate change instead: choose the cheaper route. I can guarantee that any answer involving jettisoning space trash is not an answer. The $30,000/kg is how much it costs to get space junk into a low-earth (and degrading) geosynchronous orbit. If you are thinking about shading the Earth, the space trash has to get to the L1 Lagrange point, which is ~6 times further away from Earth than the moon. I would doubt (highly) that the space trash could reach that point at less than ~$500,000/kg.

NeilT, I'm not sure if you'll see this, but if so, you have to remember that movements in our society are non-linear. Once we really start taking this situation seriously (at this point it's pretty obvious that will not begin until the blue ocean event at the North Pole, probably later), we will begin putting real investment into the issue. I'm in the U.S., as you may be able to tell from my optimism (even in the face of the recent election of an idiot fascist in my country). If the U.S. were to begin taking the issue seriously, we could invest $300 billion in subsidies per year into low carbon emissions energy production, and $200 billion in subsidies per year into efficiency technology. Assuming the subsidies cover 50% of the install costs: That would result in the construction of ~20 GW of nuclear reactors that would be constructed within a decade (85% cf, ~150 TWh/year), ~50 GW of wind power that would be constructed within 2 years (35% cf, ~150 TWh/year), and ~40 GW of solar power that would be constructed within the year (~16% cf, ~56 TWh/year)... We would be increasing our generation capacity by ~350 TWh/year/year, plus adding all of the transmission upgrades, pumped hydrostorage facilities, dam uprating on hydropower dams for load following flow release, etc... At 350 TWh/yr/yr, it would take less than a decade for us to make the required investments to fully transition our energy into low carbon options. ONE SINGLE DECADE, and at a cost of less than half of what we pay for our military today. It will take longer than that, of course, because the load demands will grow, and transmission issues will increase with distance, and switching our heating needs to work with renewable and combined power and heat generation will take time, while then transitioning into synthetic fuel made from recycled CO2 will also take time... And of course the industrializing countries will take far more time than the U.S. That's why I said it would take ~5 decades after we really take it seriously. We can do this, we just presently are not taking it seriously. When we do, it will take ~50 years. Then it will take a while for the planet to re-balance... and we will probably have to work towards sequestration...

Viddaloo, I don't dispute that it would be hard. You'll note that I assumed a ~150 year timeline from the point that the planet begins taking the issue seriously. But I think that the assumption that there will be no refreeze in the winter after 2034 is... well... farcical. The blue ocean event is coming soon, and it literally could occur any given year at this point.. but that will be a matter of hours of blue ocean at the North Pole. The average of the number of hours of blue ocean will then gradually increase each year, but it's going to be a very long time before winter refreeze doesn't happen. The warmth of absorbed sunlight will be absorbed by heating deeper water and melting the giant ice-block of the Greenland Ice Sheet (completely terrifying to contemplate), but it's unlikely that the average water temperature in the Arctic will rise much in the next hundred years. I was merely saying that once our emissions drop below the point of natural absorption, the atmospheric concentrations will begin to reduce very gradually, and eventually we'll see the number of hours (by then in the thousands) of blue ocean at the North Pole start creeping the other way slowly. I don't disagree that it will be hard. I think it will take us ~5 decades of dedicated effort to get to a point where our emissions are reduced below the point of natural absorption. I find it nothing short of absurd that, given the difficulty of such an endeavor, we're delaying the effort and just letting the problem get further out of hand... :) We do agree on most of this. I'm just saying that if you take the really long view, I believe that the gradual reformation of arctic ice is possible. :)