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Artful Dodger
Oceania
Picking your Pocket with the Invisible Hand.
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Hi Neven, Good update, and Welcome to the Scorch! Indeed, this pre-viz of dramatic Arctic sea ice collapse was created by Scientists in 1969: Scorchio! Cheers, Lodger
Toggle Commented yesterday on ASI 2016 update 1: both sides at Arctic Sea Ice
Hi John, Well, in terms of "missing something", there are three things in play in the water column: the thermocline (the temperature gradient), the halocline (the salinity gradient), and the pycnocline (the density gradient). When predicting whether a horizontal flow will sink or remain on the surface when it meets another, it's the pycnocline that matters. An example follows. This graph shows the salinity-temperature curve for sea water of equal density: http://i.stack.imgur.com/rIoFu.png Imagine that points A and B represent two physically separate surface water masses, where Pt A is stationary inside the Arctic pack ice, and Pt B is in the Gulf Stream, headed North. Both water masses begin with densities of 1.0275 g/cm^3 (see that they are on the same curve on the graph above). Pt A is at 0C and 34.25 PSU, while Pt B is at 10C and 35.62 PSU. Now if the water represented by Pt B cools to 4C during it's trip North on the surface, it's density increases to about 1.283 g/cm^3. So when B meets A, B sinks below A because it has greater density. That's how the pycnocline works. Think of it like a very long incline plane, where things (water masses) always roll down hill. Hope that helps ;^) It's obvious by reading the literature of the day that, even 50 yrs ago, scientists were concerned about the overturning circulation in the central Arctic. This ability to tap into a virtually inexhaustible reservoir of heat during the long polar night could ensure that once the fresher surface layer disappears, the pack ice isn't going to reform. Sure, some fast ice will form around the cold continental shores of the Arctic and in shallow seas, but the central Arctic basin will be open all Winter long, heated from below by the overturning circulation, and insulated from space by clouds above. And further, churned continuously by wind and waves caused by unceasing storms, driven by the temperature gradient between the central Arctic SST near 0 Celcius, and the land masses of central Siberia and Cda/AK near -30 C. So we have to ask how could the polar mixed layer break down, if reduced river outflow is insufficient? We witnesses two of these factors in abundance during GAC2012: Mechanical mixing due to wave action, and Ekman pumping due to strong wind fields over a large area and a steep horizontal pressure gradient. I don't really *care* that much about final September SIE. It could be ZERO, but if the fresh surface layer survives, the sea ice WILL reform. I have full confidence in that. There is an equilbrium state, and that includes pack ice when the Arctic has a fresh surface layer. But September SIE could just as well be over a million, but if the surface layer breaks down due to powerful fall storms, the ice pack could be gone by New Year's day. And never come back. It's the tipping point, but we just don't know where SIE will be when that threshold is crossed. I DO *care* about changes in the halocline profile of the water column. I think it's the independant variable in this planetary climatic experiment, and SIE is a dependant variable (with albedo feedbacks). I say we need better monitoring of conditions in the central basin water column. But alas, this is not easy to measure with a satellite. I'm all in favour of a fleet of new gliders to profile the water column. Anybody got a spare winning Powerball ticket? The planet you save could be your own. Cheers, Lodger
Hi folks, So the study of a perennially sea-ice free Arctic is by no means a recent research topic. See this review of the "state of the science" from more than 50 years ago: Fletcher, J.O. The Heat Budget of the Arctic Basin and its Relation to Climate, The RAND Corporation, Santa Monica, California, R-444-PR, October 1965. Fletcher (1965), in an extensive evaluation (194 pages) of existing literature dealing with the heat budget of the Arctic, visualizes an ice-free Arctic in roughly the following manner: In the Summer the ocean world absorb and store up to 90 percent of all incoming solar radiation. This would imply a slightly cooler atmosphere and hence a small increase in the intensity of atmospheric circulation. Greater amounts of evaporation would produce general cloudiness over the area. During the Winter the ocean would slowly release heat stored from the summer. Surface temperatures would be slightly above freezing in contrast to -35C under present conditions. Advection of heat from lower latitudes would thus be characterized by a constant, vigorous, year-round zonal flow with cool moist Summers and warm moist Winters. Again, paywall issues with the full 192 page report, but the above precis was included in the introduction to Norbert Untersteiner's 1969 report for the RAND Corporation. (Yes, the one and same eminent Professor of Atmospheric Sciences at the University of Washington whom Neven recently eulogized). And yes, you can download the report in full for free from the link above. (RIP, Professor U.) Cheers, Lodger
Rob Dekker | May 17, 2016 at 06:00 asked: "That article appears to be behind a paywall. Can you summarize its findings and how it relates to the statement of "an essentially ice free Arctic winter" over the next couple of decades." Hi Rob, Yeah, the full article is paywalled. I can check at my University to see if we have the journal where it was published: "Eos, Transactions American Geophysical Union" Vol 56, from July 1975. But an even more interesting paper to find might be this one, which examines the Soviet river diversion proposal with a numerical model: Semtner Jr, A. J. (1984). The climatic response of the Arctic Ocean to Soviet river diversions. Climatic change, 6(2), 109-130. Now this paper is also [bloody] paywalled, but the [free] 513 word Abstract is much more statisfying. Some highlights are: A numerical model is constructed to evaluate the effect of river diversions on the circulation of the Arctic Ocean, including the climatically important response in the extent of sea ice. Three equilibrium solutions are obtained by eighty-year integrations from simple initial conditions: the first with inflow from all rivers, the second with one-third of the inflow diverted from four major rivers (the Ob, Yenesei, Dvina, and Pechora), and the third with total diversion from those rivers. When runoff into the marginal Kara and Barents Seas is diverted, either in part or in full, almost no effect on the halocline results in the Central Arctic. In particular, deep convection does not develop in the Eurasian Basin, the possibility of which was suggested by Aagaard and Coachman (1975). The vertical stability within the two marginal seas is considerably decreased by the total diversion of four rivers, but not to the point of convective overturning. The ice extent remains nearly the same as before within the Kara and Barents Seas. This result agreed with other research conducted by Soviet scientists, in that simply diverting Western Siberian rivers would not be sufficient to remove the pack ice. So this proposal (and it was just that) failed because they didn't think it would acheive the goal, NOT because it was considered a bad idea to rid themselves to that bothersome sea ice! [smdh] Remember through all this the cause-and-effect we are examining: convective overturning in the Arctic basin and sea ice persistence. And so, more about a scenario envisioned in Fletcher (1965) leading to an sea ice-free Arctic in my next comment. ;^) Cheers, Lodger
Hi folks, Quick correction to my comment above regarding units for salinity (h/t to "John" over at Tamino's): "Ocean salinity is defined as the salt concentration (e.g., Sodium and Chlorure) in sea water. It is measured in unit of PSU (Practical Salinity Unit). It is equivalent to per thousand or (or g/kg. The 25 PSU value for sea surface salinity is important as the threshold where overturning cirulation starts to occur in a cooling water column, bringing up heat from below. A "fresher" layer will freeze as it cools, a saltier layer will sink forcing warmer water to the surface. If the warm layer is a thousand meter thick, it's not going to freeze in a single Winter." More here, as usual. :^) Cheers, Lodger
Rob Dekker wrote | May 16, 2016 at 06:36 "I have not seen any physics, or any study that project "an essentially ice free Arctic winter" over the next couple of decades." Hi Rob, This paper describes the physics: Aagaard, K., & Coachman, L. K. (1975). Toward an ice‐free Arctic ocean. Eos, Transactions American Geophysical Union, 56(7), 484-486. Abstract: The strong salinity stratification of the Arctic Ocean prevents substantial ice-free conditions in winter by suppressing convection and reducing upward heat flux from the Atlantic Water. These conditions would be significantly altered in the sensitive southern Eurasian basin if suggested diversions of western Siberian rivers were accomplished. Notice how scientists were still referring the goal of removing the Arctic sea ice pack in aspirational terms? [smh] Still, Google Scholar cites Aagaard & Coachman (1975) in 112 sources, making it a classic paper. The physics behind the halocline and heat advection show that what affects the surface salinity affects the sea ice. Lose the salinity cap, lose the sea ice. Yes, in Winter too. There's lots of heat held down below the Polar Mixed Layer: (click image for larger) The warm, salty Atlantic water is simply denser than the colder yet fresher Arctic mixed (surface) layer, and is forced to sink by gravity. Unless the two layers mix, the heat never comes to the surface. So the risk to sea ice comes when increaing surface salinity eventually reaches a treshold, causing convective overturning in the water column and giving access to that huge store of Atlantic heat. This is what leads to year-round ice-free conditions. It's just physics. But don't blame Isaac Newton. Blame those fossil fools. They've known for a long time. Cheers, Lodger
Voyageur | May 13, 2016 at 13:35 asked "could the wave action from the usual series of storms be sufficient to destroy the fresh-water lens over a single season if the CAB was essentially ice free some September?" Yes, wave mixing is one way a storm could break up the surface layer, along with Ekman pumping. Indeed, other means to remove Arctic sea ice were proposed by Soviet scientists back in the 1950s and '60s: The Soviet Scientist Who Dreamed of Melting the Arctic with a 55 Mile Dam Another Arctic geoengining proposal at the time was to divert North flowing Siberian rivers to the South. Scientists recognized that the resulting change in Arctic basin surface sality might remove the sea ice. American scientists also studied the issue in the 1960s, ie: this 1969 study from the RAND Corporation) (the quasi-Governmental "Research ANd Development" group, funded at the time by the U.S. Government). A 7MB Ebook of the 1969 study is available for free download from the link above. The RAND Corporation study was reviewed in some depth here on the ASIB by Ethan O'Connor on September 24, 2012 at 08:52. Ethan provides a summary of the recommendations made in the 1969 study: They conclude that the two most effective mechanisms for rapidly eliminating the central pack are albedo reduction and reduced net long wave radiation loss. Check, and Check, thanks to soot and net greenhouse forcing! Indeed, it wasn't until the mid '70s that scientist seriously opposed these Arctic Geoengineering plans as too risky due to associated climate effects. However, it's not obviously that major oil companies got the memo regarding the effect of "net greenhouse forcing" from increased burning of fossil fuels. Or perhaps they did. Several U.S. Attorneys General are investigating what Oil Companies knew, and when they knew it. Regards, Lodger
Hi folks, There's a simple physical process that keeps the sea ice pack in place in the Central Arctic Basin: the fresh water lens. This is the ~50ft deep surface layer of water with about 25 ppm or less salt content. The fresh water lens is maintained by: 1. brine rejection from 0-1 yr-old sea ice over the Winter months, 2. fresh water inflows from Siberian rivers and the MacKenzie delta during Spring/Summer, and 3. reduced mechanical mixing due to the wave dampening effects of sea ice. This layer of relatively fresh water literally floats on the warmer yet denser water below, which is mostly Atlantic water at 35 ppm salt content. This top layer freezes at a higher temperature, and resists mixing with the denser layer. So no matter what any individual year's melt season ends with in terms of Area/Extent/Volume, if the fresh water lens survives, the sea ice WILL recover. It's physics. Ask SHEBA. More ominously however, if the fresh water lens is broken up (ie: folded into the mixed layer by wave action and Ekman pumping from another GAC), then the sea ice is NEVER coming back. Here's why: 1. There is more that enough heat content from Atlantic water (an ~2000ft thick layer) at +4C to survive multiple Winters w/o freezing. 2. Cloud cover from surface evaporation provides ample insulation against the cold of space throughout the long Winter night. Note: Review the paleoclimate record of the Arctic basin to see how this works: Lily pads and Crocodiles in the Arctic 55 MYA. 3. Continuing the next Summer following the breakup of the fresh water lens, the albedo flip ensures that the surface layer warms up again. 4. Storms and long fetchs provide sufficient wave action to ensure the surface layer remains mixed, preventing the Northern rivers from reforming the fresh water lens in the CAB. Then, we arrive in the situation where Arctic bottom water formation ceases (there can be no brine rejection w/o new sea ice formation). The force driving the Atlantic overturning current disappears, and the current stalls. Here my science background fails me, as we are indeed entering uncharted waters. Perhaps the Gulfstream shuts down? London and Berlin freeze in the dark like Moscow? But I do know that it's gonna be ugly. Because people hate change. Or a kick in the gut. Or the head. Regards, Lodger
[pardon the interruption] The AMSR/2 raw data is multi-GB per day, and is not easily accessible w/o complex processing. I suggest that you discuss your research objectives with Wipneus, who already has a plastic straw sipping from the fire hose of data. ;^) Regarding F17 data, NSIDC put out this Press Release 2 days ago: Due to the compromised data integrity with the DMSP F17 vertically polarized 37 GHz channel (37V) of the Special Sensor Microwave Imager and Sounder (SSMIS), which is a primary channel used for sea ice development, NSIDC is halting production of the Near-Real-Time DMSP SSMIS Daily Polar Gridded Sea Ice Concentrations F17 data and switching over to the F18 satellite, starting with 1 April 2016 data. However, NSIDC is still working on the calibration of the F18 data so temporarily the F18 data will be uncalibrated and using F17 tie points. Cheers, Lodger
Toggle Commented May 8, 2016 on EGU2016, my impressions at Arctic Sea Ice
Hi Rob, The AMSR/2
Toggle Commented May 8, 2016 on EGU2016, my impressions at Arctic Sea Ice
... is being felt (smelt?) in Atlanta, Georgia. http://wildfiretoday.com/2016/05/07/smoke-from-alberta-fires-affects-the-u-s-may-7-2016/ Say Kevin, how is the air quality down there? -- Cheers, Lodger
Hi Kevin, I thing the future risk for soot from YMM (Ft McMurray) is to Greenland. Given the prevailing wind, an injection of black carbon is going to impact Greenland ice sheet melt this summer. Currently, the smoke plume from YMM
Regarding Fort McMurray wildfires: 88,000 people have been displaced. Many have no homes to return to. 1,600 homes and other structures have been destroyed as of Noon Thursday (local time). BMO (one of the largest Charter Banks in Canada) initial estimate of Insurance claims is $9 Billion. This represents over 35 years worth of civic development up in smoke. Ironically, oil production facilities North of Fort McMurray were unaffected by the fires. It's just the people that lost everything. No doubt Workers will be bussed in from refugee centres in the South when oil production resumes. Gaze upon the stark face of global corporatism: privitize profit and publicize (climate) risk. Okay, now we should "Feel the Bern". But Investment Bankers and the 1% howl incessently about their "stranded assests". SMDH. Regards, Lodger
Toggle Commented May 6, 2016 on EGU2016, my impressions at Arctic Sea Ice
Hi Bill, I'm specifically referring to the "noisyness" in this graph, the Weekly Mauna Loa CO2 measurements, which recently showed daily readings of 408 to 409 ppm: (click image to see full-screen) These daily departures are typical for MLO data, as you can see by the wide spread of daily readings (the black dots on the graph) plotted over the year. As a intimated above, these daily jiggles in the data are the peeps of an Apapane, while the accerating decadal trend in CO2 is the tail slap of a bull Kohola. Bottom line: growth in CO2 has doubled in the 40 years from the 1960s to the 2000s. That's a slap in the face we can't ignore. But we all knew that here at Neven's hangout, didn't we? It's all about our choices going forward now, isn't it? ;^) Cheers, Lodger
Toggle Commented Apr 19, 2016 on Beaufort quick update at Arctic Sea Ice
Hi folks, The thing to remember about Mauna Loa CO2 measurements is that they are naturally noisy over the short term. The Lab where the measurements are taken is about 30 miles from the Kilauea summit caldera, which emits about 10,000 tons of CO2 per day. So when then trade winds are just right (or when "Pele" is especially angry), you will see elevated CO2 measured downwind. https://goo.gl/maps/DtP3sPRBcPu But, as we all know, CO2 is a well-mixed gas in the troposphere, and the readings will even out over time. The thing that matters most is the long-term trend, and we can see decade-by-decade that trend is accelerating. That's the rock-hard fact, not the hot basalt tossed into the Pacific. Undeniably. Cheers, Lodger
Toggle Commented Apr 19, 2016 on Beaufort quick update at Arctic Sea Ice
MrVillabolo wrote: "I'm waiting for the first cross polar cruise. That might teach the elite a lesson." Hi, VB. So sorry to report we missed the first sailing of Ship One back in '88 (Captain Hansen, 1st Officer Mann). Luckily, the second ship is preparing to sale even as we speak. Most excitingly, it is reserved exclusively for Elites, Luke-warmists and Offshore Phishermen wearing Panama hats. The third arc will follow shortly after the second one departs. Trust me. I'll be on that ship. ;^) Cheers, Lodger
Hi Jai, Well stated, though it may be better to specify that "the [Northern] summer months has absolutely no sunshine in Antarctica. Therefore, there is no albedo effect." Indeed the real issue in Antarctica (which deniers prefer you ignore), is the loss of land ice, not sea ice. This is hardly surprising, since Antarctica is continental land surrounded by ocean, the reverse of the Arctic. Still, climate deniers much prefer that you cluck'n'peck around the barnyard, all the while ignoring the 'Elephant' in the coop. So click the image if you're not chicken: For more never-ending GObstoPer fun, see the lecture-video from Denial101x - Making Sense of Science Denial Cheers, Lodger
Currently, a lot of work is underway comparing the paleoclimate record to Global Climate models in order to determine why those models vastly underestimate Arctic warming during the mPWP (about 3 million years ago). Here is one such study: Howell, Fergus W., et al. "Can uncertainties in sea ice albedo reconcile patterns of data‐model discord for the Pliocene and 20th/21st centuries?" Geophysical Research Letters 41.6 (2014): 2011-2018. A comprehensive review paper is in Prepress for Nature Communications which outlines progress, challenges and future direction in efforts to integrate pliocene geological archives and climate models. I'll alert the group when this paper is published online by Nature, or if you can't wait msg me on the ASI Forum for a pointer to the draft copy. Cheers, Lodger
Toggle Commented Apr 11, 2015 on The Ns are calling the maximum at Arctic Sea Ice
Lord Soth wrote | April 01, 2015 at 02:14 "The big question is, will that shrinking donut hole of ice free central arctic completely freeze over. If not, expect a regime change to a ice free central arctic during the winter." Indeed, L.S. In fact the only way Climate Modelers have been able to reproduce mid-Pliocene (3.264 to 3.025 million years ago) temperature in the Arctic is by forcing Winter sea-ice extent to zero: Ice-free Arctic winters could explain amplified warming during Pliocene During the mid-Pliocene Warm Period (mPWP), global temperatures were just 2-3°C warmer than today, yet annual Arctic temperatures were 10-20°C warmer than today. This is important because during the mPWP, atmospheric CO2 concentration was also around 400 ppm. With a similar configuration of continents and mountain ranges compared to modern times, the mPWP is considered an important analogue for the 21st Century climate. Cheers, Lodger
Toggle Commented Apr 11, 2015 on The Ns are calling the maximum at Arctic Sea Ice
Welcome back, Seke Rob. Looking forward to more of your excellent charts and graphs. Saluti! Cheers, Lodger
Toggle Commented Mar 30, 2015 on Shock news! at Arctic Sea Ice
Hi Folks, Happy 1st day of Spring! (or Fall, depending on your declinations...) Meanwhile for the Arctic, the NSIDC has called the Max: (provisionally, of course, as with most things Arctic ;^) 14.54 M km^2 on Feb 25, 2015. Note that NSIDC uses a 5-day trailing average to report SIE. Significantly, that minimum occurred about 15 days earlier than average. So then, will it be 'Cry Havoc, and let slip the sled-dogs of war' for Arctic Summer 2015? El Nino effects? Wayne? Cheers, Lodger
Toggle Commented Mar 20, 2015 on Early record, late record at Arctic Sea Ice
Hi all, Steve, Larry, awesome that you're going to the AGU Fall Meeting. You'll do our 'blog proud. :^) Neven, time for that first sign of Winter, Open Thread No. 1? Cheers, Lodger
Toggle Commented Oct 31, 2014 on PIOMAS October 2014 at Arctic Sea Ice
"But now I'm 'stuck' with "gotten to the bottom to" (which I would have written "gotten to the bottom of"). Ahhh, saved by my own ego. (Please, somebody, don't leave my post the last one in.)" Not to worry, Tor. Ah jolly old England, where the rules of grammar are as stable as an iceberg, just before it tips... ;^) In this case, I think we would properly convert the prepositional phrase (the "get to the bottom of" part) into a verb phrase. Ergo, "We need to get to the bottom of so much". And remember, the keel of the iceberg is 90% of it's total (pio)mass. So there's a lot of "bottom". :^) Cheers, Lodger
Toggle Commented Oct 20, 2014 on PIOMAS October 2014 at Arctic Sea Ice
Hi Rob, An R of 0.94 (R-Squared of 0.8836) is impressive: this simple model shows that 94% of the variability in September SIE is explained by May snow cover. So then, what are the correlations with all other months? In particular, I'd be interested in Feb snow cover, as this may show a high negative correlation to Sep SIE. The high albedo of snow also means good insulation of the ground during the coldest months. More snow on land, less freeze of permafrost and more water to runoff in Spring. Apologies if you've mentioned this previously, do have a link to the numerical data for NH snow extent? I'd like to muck about with the data a bit. :^) Land change is an important topic for the Arctic. Have you seen this paper, included in IPCC4, WG1, chp 4 :^) Lemke, P., J. Ren, R.B. Alley, I. Allison, J. Carrasco, G. Flato, Y. Fujii, G. Kaser, P. Mote, R.H. Thomas and T. Zhang, 2007: Observations: Changes in Snow, Ice and Frozen Ground. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. How about including Arctic river outflow? I'd think there would be some auto-correlation with snow extent, since the underlying variable (heat) is captured by melt rate. Maybe there's a way to tease out heat flux? This map of Arctic outflowing river basins shows starkly how important Greenland will be to the future heat budget of the Arctic. 2012 was MOST notable for the widespread (and ominous) melt of the Greenland ice cap (a first since at least 1898), whereas SIE loss was more of the same... Cheers, Lodger
Oh, and Happy 4th of July to all my American cousins! ;^)