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DCS, whilst the logic of losing a greater amount, of less ice, means that less volume is lost overall; there are a few gotcha's in that calculation when it comes to the reality of sea ice loss. First and foremost is that the amount of ice lost tends to be correlated to the amount of energy entering into the system. Given weather and other mechanisms throw a spanner in the works, it is still a case that measured w/m^2 input gives us x% of ice loss. If we have less ice to lose, then the ice is not doing its job of offsetting the input of energy. In that case, in a 2007/12 scenario, the ocean and land of the Arctic is going to take up the offset with heat absorption. Whilst more sea is roughly equivalent to more heat transferred to the atmosphere at the onset of winter, the rapid onset of Arctic winter can cap the heat transfer and retain a portion of that heat. Regardless, instead of reflecting and radiating out to space or being used to transition ice to water, the heat will be absorbed and some will remain in the system. You mentioned that in terms of albedo but not in the sheer amount of fusion energy required to change ice to water 333kj per kg, without changing the temp by 1k. The less ice we melt to water, the less fusion energy we take up, over and above all the other energy to move it from -5 or less. Essentially we have a smaller aircon so we get hotter. How this balances with having a smaller blanket (initially), in winter is an interesting point, but the other point is that this heat, initially, transfers to the local atmosphere. Inhibiting further ice generation until it can be moved away by the weather systems. The other point you didn't mention is this. Right now the thermal inertia of the current volume of ice is greater than the thermal inertia of any single melting season. Thus it is, essentially, impossible to lose the entire pack in one melting season. However, as the average thickness of the ice reduces towards 1m and the area of that ice declines, we reach the state where the thermal inertia of the ice becomes less than a single exceptional melting season. Which puts the Arctic into a shooting gallery for any exceptional melting season. So whilst the math and the stats are valid, in terms of reduction; so is the fact that the entire system can flip to another state right in front of our eyes.
Commented Dec 3, 2017 on PIOMAS November 2017 at Arctic Sea Ice
Due to picking up a new job in the "project from hell" arena, I completely missed the entire end of the melting season. As Neven says, Nothing can be taken for granted with the Arctic. For me the most concerning thing is we saw exceptionally low summer temperatures, yet we still finished 4th. Which means that the damage was already done in the preceding year and in the preceding winter. I wonder if we'll eventually see this as a small bounce driven by the end of an exceptionally strong Nino which overwhelmed the early signature. I guess the post mortem of the 2017 melt season will take a few years and throw up a few interesting things. I'm now in watching mode till the end of the 2018 melt season as I want to see how it all plays out.
Commented Nov 5, 2017 on PIOMAS October 2017 at Arctic Sea Ice
Commented Aug 7, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Let me quantify. "We believe" was Hans and me as I was replying to his question.
Commented Aug 1, 2017 on PIOMAS July 2017 at Arctic Sea Ice
How about a slightly different question. If, as we believe, the cycle has years predisposed to melt as well as years predisposed to ice growth, then it would take exceptional weather to stop the melt this year. That is somewhat different than believing that it will take exceptional weather to create a surprising melt this year.
Commented Jul 31, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Thanks Jim, I should have said tends to be saltier. That would have been better and more accurate.
Commented Jul 24, 2017 on PIOMAS July 2017 at Arctic Sea Ice
AJbT, because we know the SST's in the areas where it is melting and we know that the currents draw that warmer water under the CAB. Prior Buoy data over the affected areas has given us a wealth of stats which show a range of bottom melt during the season. We also know the thickness of the ice and we know that FYI suffers from solar penetration and insolation of the solar energy in the water below. Also causing bottom melt. FYI is predominantly salty ice which has not built up a store of snow and frozen water from rain which did not escape. Salty ice melts at -1.8C. So we know bottom melt is going on, we know roughly how much will melt, in a normal season and we know how thick the ice is. That is leading to some concerns as to the retention of the ice this melting season.
Commented Jul 24, 2017 on PIOMAS July 2017 at Arctic Sea Ice
I noticed the same thing Hans. Where it is melting on the Atlantic side, it's coming around the coast. Where it is not melting in the CAB, it's coming over Greenland and rotating over the CAB. What is more interesting is the state of the ice on the Atlantic side, now showing on the Bremen concentration maps as areas of open water N of 85N. Also the bottom melt continues but is relatively invisible at this time. It's going to make August rather interesting.
Commented Jul 23, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Not quite AJbT. I used to put every day under the microscope, I used to try and understand why each day and week were doing what they were doing. None of it made any sense because every year seemed different. It was only when I took a step back and looked much further out and did comparisons way beyond day, week, month or year that some things seemed to make sense. But, yes, I'm still trying to learn. I didn't use to have much patience for RealClimate's assertion that you could only see what was happening on a multi decadal scale. Especially when things were moving so fast and accelerating so fast. I have moved much more towards their way of thinking over the last few years.
Commented Jul 20, 2017 on PIOMAS July 2017 at Arctic Sea Ice
I was recently looking back through the Chartic extent. Roughly: 2006 reached the 2003 low 2011 reached the 2007 low But 2016 only really equalled 2011. It didn't reach 2012. So, in a way, I would not be surprised if we only equalled 2012 or went under it slightly. Of course if we went significantly under it, I would not be surprised either. However, for me, I'm still looking forward to 2018/19 to see whether we continue with the losses of 2016/17 or whether we go back to a cycle of very limited re-growth for 2 years. What is looking most interesting, to me, is the swathe of ice in the 80n to 85n from Svalbard to the Chuchki. That looks vulnerable to a storm or two which could cause a very significant change in the ice. Or not.. That is the whole thing about watching the Arctic. For me I have come to the conclusion, in my quest to understand why the ice does what it does, that if we have 5 year cycles, then each year within that cycle is a different melt season. 2017 is peak melt so should act like peak melt. 2018 will be peak growth and should act like peak growth. It has been and will continue to be very interesting to watch.
Commented Jul 20, 2017 on PIOMAS July 2017 at Arctic Sea Ice
We, it seems to me Hans, are talking about serious advection of heat: are we not? I'd say we have already had serious advection of heat in the form of rain, all over the season. The main reason it has not really registered heavily so far, in terms of overall ice melt, I'd guess, is the very heavy snow cover. But that heat is there and it's not going away. More heat just increases the impact on an already weakened system. This seems to me to be one of the drivers that has driven the state of the CAB where it no longer resembles a pack.
Commented Jul 19, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Looking at the way the Atlantic side is disintegrating, on the Arctic Mosaic overheads, I'm quite interested to see how close the daily Extent on NSIDC gets to 3M There is now significant damage on the Pacific side, significant damage on the Atlantic side and the periphery is finally succumbing to the relentless heat and rain. Volume is also showing that it's starting to dip more sharply again, hardly surprising given the amount of area and extent that has been vanishing in the last two weeks. NSIDC running 5 day average has 2017 just above 2012 but closing as the higher rates of loss in 2017 compare to the lower rates of loss in 2012 at this time. Regardless of what happens now, it looks like 2017 will drop well below 2016 and I'm looking forward towards the next freezing season and how it evolves. Personally I see the next two freezing seasons and their attendant melting seasons following as the final story in the potential for a 5 year cycle.
Commented Jul 18, 2017 on PIOMAS July 2017 at Arctic Sea Ice
P-maker. I know you weren't discussing a cycle. Only a few of us do that.. :-) Apart from the fact that pretty much all the peripheral ice melts out nowadays and the peripheral ice is mainly very thin, I would assume that less surface contact with heat transfer would generate less melt. It doesn't matter quite so much if there are 100,000 sq miles of warmer water or 1M sq miles of warmer water, if only 80,000 sq miles of water is in contact with the ice whereas before there was a full 100,000. Yes there is a larger "warm sink" but heat transfer through water is not very fast and also the melting ice creates a barrier between the ice and the warm water surrounding it. At least for a while.
Commented Jul 15, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Hence, the June cliff may be the cause of the late summer decline in total loss (simply less ice available). Oddly I thought that was what I'd said.
Commented Jul 14, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Rob, would that be due to the fact that there was more peripheral, weak, thin, ice out there later in the season in the 80's than now? We have seen all the peripheral ice melt out in the last decade, only leaving CAB ice behind. This was not true in the 80's. As the ice reaches total failure point, volume loss, in the latter part of the season, must start to fall in the charts because there is simply less surface area, everywhere, to absorb heat, because there is less area and extent. The more compact the ice the less area too. Then, of course, we have to wonder about rotten ice. It gives every signature of MYI, but has the strength and heat absorption capability of FYI or less. We know the satellites can't detect rotten ice so, I wonder, how do the models compensate. If the ice is melting from within, but not giving a signal of melting, then, would we not, see something similar to this slowdown? I did find an abstract about the heat sequestration and transport of melting snow cover on ice, I requested the full article and received a reply of "when the authors deliver it". I think, in the case of this year, it could be important too. Right now we are almost at solar minimum, Nino is neutral, there does not seem to be any single,"normal" driving force for what we are seeing today. Yet, we're bumping along the bottom of the lowest charts for Extent and Area and off the bottom for Volume. This would fit the hypotheses of a cycle, where the Arctic responds in a certain way throughout the cycle. Influenced by strong weather, certainly, but without strong influence it continues on the path. The CAB is in a very poor state today, peripheral areas to the CAB are likely to melt out, the NSR and the NW passage look likely to be open in the next 2-3 weeks and we still have August and the storms it might bring to come. The last 3 days has seen Extent drop by an average of 132k per day which will drop 2017 much closer to 2012. 2012 only averaged sub 100k over those same days. However the overheads show the peripheral ice changing colour and likely to disappear faster, not slower. Nothing can be forecast, right now, from observations because they are not that consistent. That being said, we can make some assumptions. My assumption will be that this melt will continue to exceed expectations in the periphery and the CAB will continue to show a weak and broken state. That then leaves us in the shooting gallery of August storms as to whether there is a record or not. I do, however, expect it to drop significantly below 2016.
Commented Jul 14, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Thanks for the time and insight Bill. I won't even discuss this in the forum any more, the discussion is too toxic. I was doing no more than setting out my stall for why I believed that 2016 was going to stall, why it was not going to make a record and why I believed it was going to set the scene for a 2017 which could be a record breaker. In contrast to the "false alarms" and predicting abrupt sea ice loss, I believe Hans and I have been doing the opposite. Where we are predicting another 2 year pause on the journey to destruction starting this freezing season and rolling back again in 2020. Then leading up to another sharp drop again in 2022. I have been very careful not to promote huge new records for 2017, but have talked more about unexpected levels of melt for the year consistent with ending the 5 year cycle. If we look at 2017, with high snow cover, low volume and indifferent weather, the levels of reduction in all three metrics are, in truth, unexpected. 2017 should not be at, or around, the bottom of the extent and volume tables given the atmospherics. One other point. I was looking back to 2002 on the AMSRE archive on the Bremen site when I realised that, looking at the images, we are in the 3rd round of a 5 year cycle. Have a look at 2002, the re-growth in 2003/4 and the path to 2007 with 2005/6 leading the way. It may not be so obvious from the numbers but it is quite obvious from the shape and pattern of the ice. In the end, there is nothing left to do but wait. We won't know, for sure, until Autumn 2018 whether this is going on, still, or not.
Commented Jul 7, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
I'd say more like Heartbroken that Neven doesn't have the time to fully embrace the defining events of our lives and communicate it to us all in his excellent style. It is soul destroying to see what is happening but be unable to keep this community engaged and talking and visible to the world; so that everyone can understand what is going on. My view? Regardless of what is happening and how important this is, family comes first. After family there is time to worry about everyone else. This is slow enough moving with such huge inertia behind it, that it will still be here in a few years when family pressures have eased and there is more time in life.
Commented Jul 7, 2017 on PIOMAS July 2017 at Arctic Sea Ice
I guess time will tell Rob. 2017 is still at the lowest on volume, almost at the lowest on extent and not there yet on area. As you say snow has had a big impact but, also, snow has insulated the ice over the winter from growth and, in many areas, is 0.5m thinner than it should be. I know very well that area is the figure to follow, but unless I build my own charting model from the data, chartic is the easiest tool for me to use right now, given that CT area is now gone. So I'm watching extent. The Beaufort is almost open to the Pacific, the Laptev, ESS and Chuchki are all continuing to draw back. The Laptev bite is well in progress and the big unknown is what will happen with the Atlantic side. We have 3 weeks of July left and all of August. Whilst extent may be stalling, there is a lot of peripheral ice out there which is vulnerable and will likely melt out. Whatever happens, it will be extremely interesting. More so because of the lack of melting input, compared to the state of the ice.
Commented Jul 7, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
Thanks Bill, I knew about the rolling daily average but wasn't quite so aware that the values in the spreadsheet were monthly averages rather than lows. That makes a lot of sense. The problem with the 5 year cycle is that we won't know, even at a low level of certainty, until 2020. Because 2018 and 2019 need to show some re-growth from a low in 2017 and then the cycle of dropping melt needs to begin again. For me the real evidence won't come up until 2021/22. If we see second iteration of 2006/7 this year followed by a re-growth and then a third one in 2021/22, then I'd say that it's fairly certain that a cycle is going on there. This month is a busy month in the extent records. Years drop into and out of the record lows this month. 2010 and 2006 drop out. 2011 drops in and out again, 2012 gets set to smash all records in August/Sept. Much more waiting to go before we have any idea how it's going to end up, but even then one GAC and anything could change. Some of this ice is very thin and other ice is thinning without vanishing. I recall the ice in the Chuchki/ESS which just looked like smoke on the water. It was counted fully as extent and area but when the GAC came it just vanished. So I'm making no predictions right now, but the fact is that 2017 is right at the bottom of the charts right now and the only reason it is there is the very sorry state of the ice from the 2016 melt and the very low winter ice growth into 2017. Which leaves the ice very vulnerable.
Commented Jul 6, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
Thus continuing the 5 year cycle as far as I'm concerned. Of course for that to truly continue we'll need to see ice re-growth and slow summer melt in 2018/19. There is also the opportunity for some more than average melt in July and August, therefore driving 2017 even lower. I believe, if I remember correctly, that 2012 was not an exceptional season until the GAC. I believe my focus on Arctic melt has changed. I still watch it daily to see what is going on but my anticipation levels have changed to annual rather than weekly or even monthly. I no longer obsess over the next few days or weeks. I am looking months forwards and backwards. Whilst not as instantly gratifying, the overall experience is more positive.
Commented Jul 5, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
In those extent and area stats, the differences between 2006/7 1.63 extent, 1.19 area 2011/12 1 extent, 0.81 area. I have an issue with the last stat for 2016 as chartic says it was 4.13 and this csv says it was 4.72. If we see a 2007 style drop between 2016 and 2017, then we're well into new territory. If we see a 2011/12 style drop then we are still continuing the trend. If we see the same reduction in drop, from 2007 to 2016, we don't get a new record and the cycle stalls. Onwards to September. This is not an exceptional melting season, so far. The most exceptional thing about the melting season is how fast it is vanishing (tracking 2012), with an average input of heat and insolation. Which is, in the end, what global warming is all about. Step changes where the environment has changed so much that smaller input is required to tip it.
Commented Jul 4, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
Hans, talking about comparisons gave me a thought. What are we really talking about here if we are talking about an emergence of a 5 year cycle? Given that this should be the culmination of another 5 year cycle, what would extent and area look like if it were an event of the same magnitude? To define magnitude, I think we need to look at the long term average extent and average area, at its September minimum, then the divergence from that average at each cycle peak melt. For 2007, average 1979 to 2006 the average September minimum is: Extent 6.86 Area 4.84 2007 actuals Extent 4.32 divergence from the average September minimum 2.54 Area 3.12 divergence from the average September minimum 1.69 For 2012, average 1979 to 2011 the average September minimum is: Extent 6.54 Area 4.63 2012 actuals Extent 3.63 divergence from the average September minimum 2.91 Area 2.82 divergence from the average September minimum 1.81 Now if we assume the cycle is continuing, then we would expect to see, at least, the same change and, in a declining arctic, perhaps more. Rate of change in the divergence from the peak melt average September minimum between 2007 and 2012 Extent 0.38 Area 0.12 In essence that is all that requires to change, as an increase from the divergence from the satellite record average September minimum, for this to be a continuation of the 5 year cycle. In real terms I make that the following divergence from the satellite record average September minimum in 2017. Extent 3.01 Area 2.57. Also the average September minimum has declined, of course, including 2012 and now stands at: 1979 - 2016 average September minimum Extent 6.31 Area 4.49. So, if my spreadsheet is correct, if we see a minimum of 3.01 in extent and 2.57 in area or something very close, then this is a continuation of the trend. For me. All figures from the NOOA monthly data for September ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/monthly/data/N_09_extent_v2.1.csv
Commented Jul 3, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
Well the barrow ice is not quite gone and, still, is not going anywhere on the wind. It does seem to me that some of it is protected by the layer of snow that it got. Which presents a question. A thick layer of snow will protect the ice, both from freezing and melting. However when it melts that presents an absolutely huge heat transfer in water, both to the ice below and the water below that. I wonder if anyone has actually calculated the heat transfer of that much liquid water (sitting on top of the ice) and what it's impact would be as it drains away. Does snow absorb the heat in melting, only to release it like a bomb later? Because, in that case, things could get a little rapid.
Commented Jul 1, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
I did Hans. Looks like all that snow is suffering serious melt now. When it's gone we'll see what the shape of the ice is like for the rest of the melting season. Barrow ice pretty much vanished in front of the camera yesterday, it's still lingering up to the point but wont last long with clear skies and high temps. What is most interesting to me, right now, is the state of the ice from the Kara right into the pole. Last year there was a barrier of 2M ice blocking all intrusions from the Atlantic. It doesn't seem to be the same in 2017. Still, as is being said on the forum, the fact that melt has really kicked in only at the end of June will impact what happens at the end of August. Of course, assuming the thickness estimates are correct. Volume is still at an all time low and the ice is in a seriously degraded state given the slow start. Then again I still see 2017 tracking roughly, in extent, with 2007 and still well below. We shall see. I see three key points in the historical extent chart I'm following. First week in July, Mid July and the first week in August. More watching.
Commented Jun 28, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
And, as of the latest image, at the time of writing, the temp is 52F and that is bright sunshine.
Commented Jun 27, 2017 on Melting momentum: May 2017 at Arctic Sea Ice