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Chris Reynolds
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Wow, that's terrible news. So long Blizzard. :(
Toggle Commented Oct 2, 2016 on In memoriam: Andrew Slater at Arctic Sea Ice
There is no expectation of a record this year using the late June Compactness indicator.
Toggle Commented Jun 29, 2016 on 2016 melting momentum, part 2 at Arctic Sea Ice
SH, I knew it was when I posted it, what I missed were the two 'buts'. It was the best I could manage after working 6:45 to 20:00. IceBunny, Thanks, I did however have to resort to a webpage of rhymes with 'panic/manic' to get the 'titanic'. Sofouk, Titanic? If PIOMAS follows the behaviour of DMI Cice, this year's spring melt looks likely not to to be very strong. In 2012 it was massive and probably played a role in preconditioning for the July/Aug losses.
Toggle Commented Jun 19, 2016 on 2016 melting momentum, part 1 at Arctic Sea Ice
iamli3, That's rather a solid page of whackadoodle nonsense you linked to there. You might find a more gullible audience that's more to your liking is available of at WUWT.
Toggle Commented Jun 18, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
P Maker, "John, If you take a closer look at the DMI 80N graph for 2012, you will see a nice 10 K "flash freeze" around day # 75. That ought to be enogh to keep the sea ice back then in good shape for the melt season to arrive." Huh? Around that day number (15 March 2012) it was roughly -20degC. 273K is roughly 0degC. Icebunny, I always have an early season panic. But unlike others I tend not to get manic. But to be fair. I have to declare. I conceded the chance of a summer titanic.
Toggle Commented Jun 17, 2016 on 2016 melting momentum, part 1 at Arctic Sea Ice
Thanks Rob, That's great news. :)
Toggle Commented Jun 15, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
"Chris said : I have pointed it out - the whole paper. I'm sorry Chris. That is the very definition of what you accuse me of (being "evasive")." Now what did I actually say? I said "I have pointed it out - the whole paper. Really your request is like asking what symbol in a quadratic equation gives rise to its behaviour." My hypothesis of flattening ice extent after 2007 isn't my hypothesis. It is what the data shows, but it is too early for statistical significance. "Look at it back to basics : Since FYI melts out faster than MYI, we would expect sensitivity to climate forcing to INCREASE, not decrease as Armour suggests, as the Arctic transitions to an ice free state." I'm sorry but your 'basics' are totally wrong. That you could make the above statement suggests to me that really don't get either Bitz & Roe or the Armour paper. With a longer 'memory' MYI 'remembers' the losses and carries the losses forwards into following years. With short 'memory' FYI 'forgets' each winter as the ice grows back (what do we see after years like 2007 and 2012? - massive winter growth). As FYI takes over the overall memory decreases with thinning at the overall climatological warming rate, not with the more rapid decline of MYI. Look at figure 1 of Bitz & Roe. Why is that happening? Why does PIOMAS show the same behaviour? Bitz & Roe have explained it IMO, Armour expands on a consequence of Bitz & Roe. It is not only myself that accepts Bitz & Roe, here are the citations of that paper (83) from Google Scholar.,5&hl=en There is no point in continuing this discussion further.
Toggle Commented Jun 14, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Wayne, It's looking possible. But the standard deviation of the ensemble seems to be large enough to imply it doesn't happen in all of the ensemble members. Colorado Bob, There was a similar unexplained explosion a few years back in the Canadian Arctic Archipelgo. Sorry I can't remember the details.
Toggle Commented Jun 14, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
Neil, 2006 was another El Nino year wasn't it? But not very strong I think. I still don't know whether the EN will reduce (weather) or increase (ocean heat (and weather?)) ice loss. John/Hans, I picked 4 and 4.25 due to the expectation of beating 2007. I'd willingly slip a box above or below right now.
Toggle Commented Jun 13, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
John, I have been thinking about Screen et al 2011 "Dramatic interannual changes of perennial Arctic sea ice linked to abnormal summer storm activity." "...fewer cyclones over the central Arctic Ocean during the months of May, June, and July appear to favor a low sea ice area at the end of the melt season. Years with large losses of sea ice are characterized by abnormal cyclone distributions and tracks: they lack the normal maximum in cyclone activity over the central Arctic Ocean, and cyclones that track from Eurasia into the central Arctic are largely absent. Fewer storms are associated with above‐average mean sea level pressure, strengthened anticyclonic winds, an intensification of the transpolar drift stream, and reduced cloud cover, all of which favor ice melt. It is also shown that a strengthening of the central Arctic cyclone maximum helps preserve the ice cover, although the association is weaker than that between low cyclone activity and reduced sea ice. The results suggest that changes in cyclone occurrence during late spring and early summer have preconditioning effects on the sea ice cover and exert a strong influence on the amount of sea ice that survives the melt season." As of the last available GFS forecast it does indeed look like the Greenland Ridge might be going to spread a high over the Arctic Ocean. But that's so far off in terms of forecasts I'm just waiting to see. Wayne, I'll keep an eye on that. Both, The interesting question is if the (poor) weather can over-ride ice state and impede melt. However Dr Slater's persistence model seems to suggest that current concentration patterns are sufficient to keep extent low. Which would mean 2007 and 2011 being beaten - possibly. That said his persistence prediction map suggests something I've been expecting. A persistence of sporadic ice into late summer, possibly enough to keep extent up in the East Siberian Sea by September. Ice concentration difference from 2012 is still not massively below 2012, indeed it's higher than 2012 in some regions. On balance something between 2012 and 2007 looks reasonable this year. Below 2012 seems rather unlikely to me. To maximise impact I'd rather see clear open skies through June, as in 2012, clear open skies after that (through July) was what we had in 2015. Ice state is worse than in 2015, but not so bad it supports below 2012 without serious help from the weather. But by the end of this month we should see compactness crash if we're going to see something really exciting. So far over much of the pack compactness is pretty much the same as the last few years. I need a longer dataset, AMSR2 is so short as to be of limited use.
Toggle Commented Jun 13, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
I have pointed it out - the whole paper. Really your request is like asking what symbol in a quadratic equation gives rise to its behaviour. Can you see why I see you as evasive - I point to papers to support my case and you throw back daft demands. To me the issue is quite clear, as it is in Bitz & Roe. In essence the issue is that FYI grows back in a single winter. MYI takes years to form. Therefore MYI has a longer memory than FYI. You can see this in the PIOMAS data, the loss of multi year ice (thickest) in April aligns with the decline in September extent. Now why do you think that would be?
Toggle Commented Jun 13, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Rob, Rob, I'm sorry, you probably got caught up in my anger over the Orlando massacre. That said, I think you're doing it once again in the comment immediately above. Playing games to avoid the issue. That paper was presented at the autumn AGU meeting in September 2009. It is hosted on Cecilia Bitz's website. Blanchard-Wrigglesworth, Eisenman, and Gerard Roe all offered comments (on an earlier version). Anyway, as I see it, it is suppoorted by Bitz & Roe. It's just an exploration of an implication of Bitz and Roe. I use the Armour paper because the phrasing of the paragraph I quoted is so perfect. Anyway, their finding that " is unlikely that a “tipping point” in September ice area and volume will be reached as the climate is further warmed." has since been backed up by Wagner & Eisenman. That was published in a peer reviewed journal. Anyway, I have just stumbled upon a more interesting subject from a paper over at Eisenman's site.
Toggle Commented Jun 13, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
The turn in the weather really has surprised me.
Toggle Commented Jun 12, 2016 on ASI 2016 update 2: closing the gap at Arctic Sea Ice
Kevin, Lake ice, snow cover, Arctic sea ice, are all being driven by AGW, with feedbacks driving sub trends within each metric, and feedbacks between the metrics. I cannot extricate those feedbacks without a model. However I have presented evidence from a PIOMAS based study that finds sensible air temperature is not a driver for the recent loss of volume - it's an ice/ocean (and ice albedo) albedo feedback. And I have presented a study that supports modelled temperature increases over land adjacent to ocean being higher due to ocean warming, even in April and May. What I am trying to get over is that the suggestion that snow is driving ice loss, whilst currently fashionable, is far from a conclusive case. Note that for all potential explanatory variables, the greatest losses in 2010 and 2012 are clear outliers, not explained by the explanatory variables. Using the residuals from the linear fit of ice thickness and may volume loss, a linear fit of temperature to the residuals has an R2 of 0.11, for snow that is 0.03. With an increase in variability that may be the case post 2007 (at present the effect seems largely to be due to 2007 and 2012), it may take longer than the rest of this decade to establish any inflection post 2007. Post-mortem? Perhaps, but after Eisenmann and Wagner pulled the rug from the fast crashers I struggle to see the evidenced argument for such an expectation. FWIW I am not seeing such an indication in the underlying data. Ultimately there is probably little between the expectations of Rob and myself. Rob seems to expect a virtually ice free state within a few years (by 2020?). I used to think that but have reconsidered and now put it sometime next decade, possibly later (there is substantial uncertainty). But that isn't the main issue: What made me so angry this morning was what I see as a dismissal, and evasion of, the points myself and DCS have put forward.
Toggle Commented Jun 12, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Fish (D), As long as there is ice survival in the summer mechanical deformation will continue to build up thickness of the northern coast of the CAA. The trend in decline of the Atlantic Ocean dominated losses (e.g. Barents) is far stronger than any of the seas within the Arctic Ocean Basin. This suggests a decoupling. The primary issue here is probably the depth of AW within the Arctic Ocean basin, and the maintenance of the halocline due to winter ice growth. Winter ice growth will continue to be strong as long as the winter remains cold. This winter was a blip due to an ENSO. Bitz 2006 associates Rapid Ice Loss Events (RILEs) with ocean influx of heat. Notably, so far we have not seen any period since 1979 meet the criteria set in that paper for a RILE. Across much of the pack (peripheral seas), April thickness is already such that it is below or equal to summer melt. Hence those seas are virtually seasonal. However the ice edge progression to the central Arctic means losses there only start in July, and even in 2012, the strong declines in extent in that region only started in early August, at a minimum of around 2.5M km^2 this is 1.5M above a daily min of 1M and further from the monthly average for September of 1M km^2 (virtually ice free). Taking the 2012 loss rate between 1/8/12 and 1/9/12 (linear R2=0.99), one would have to start the extent loss at that rate on 13 June to get to 1 million daily by 1 September. Since 2010 Arctic Ocean April volume has not dropped below 19k km^3.
Toggle Commented Jun 12, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Rob, "Note that Lawrence was talking about AUTUMN, not spring." Staggered. I am really staggered. Figure 1 panel b) (graph) and more to the point - figure 2 panel a). April/May both show anomalous warming. "I read the paper today, but I did not find any evidence for the claim that " the difference between FY and MY ice survival ratios will decrease in a warming climate"" Then you just don't get it, or more to the point don't want to. Do you think that you'll get closer to reality by arguing like a lawyer? There really is no point in discussing anything with you.
Toggle Commented Jun 12, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Rob, "Chris, "regime change" is a very un-satisfying term, as it has no relation to physics. You mention Lindsay & Zhang 2004, who report that feedback due to ice losses is amplifying ice losses since the mid 1990's, which actually makes my point that albedo change causes the September losses to accelerate." No relationship to physics?? Have you even bothered to read L&Z?? Their hypothesis is that the impacts of the AO and PDO in the mid 1990s set into play a new regime of sea ice albedo driven volume loss. If you're looking at PIOMAS volume data, the key paper to understand it is L&Z. Your point regards albedo loss has been about snow albedo on land, has it not? L&Z find that in the PIOMAS model the decline of volume has been driven by sea ice albedo and ice/ocean albedo feedbacks. On this subject you might want to consider Lawrence 2008, paragraphs 7 & 8, and figure 2. That supports the interpretation that loss of sea ice drives the adjacent land warming. "I am totally at a loss as to why you believe that there is a third "regime" that sets in after 2007, and " the trend since 2007 in Sept extent is level". Did the that feedback that Lindsay & Zhang were talking about suddenly come to a grinding halt after 2007 ?" No. But the albedo feedback acted preferentially on multi year ice not first year ice. This is due to the differing time constants (memory) of the two classes of ice. This is explained by Armour et al 2010, "Controls on Arctic Sea Ice from First-Year and Multiyear Ice Survivability." "Given the strong thickness–growth feedback of sea ice (Bitz and Roe 2004), where in a warming climate we can expect the thicker MY ice to thin at a greater rate than the thinner FY ice, and the fact that the ratio of MY to FY ice entering into the MY ice category each year is decreasing, it is likely that the difference between FY and MY ice survival ratios will decrease in a warming climate. If this occurs, the Arctic sea ice system would move toward a regime of decreased memory and decreased sensitivity to climate forcing..." Note that last sentence: "...a regime of decreased memory and decreased sensitivity to climate forcing..." It is a vitally important point! If you don't get it, read Bitz and Roe 2004 "A Mechanism for the High Rate of Sea Ice Thinning in the Arctic Ocean." Once you understand Bitz & Roe you will understand the statement by Armour. If you read Bitz & Roe and still think the statement by Armour is wrong - you haven't understood Bitz & Roe. "Neither one of these shows that "graphs that accelerate and then decelerate fit the data better than graphs that accelerate and then continue accelerating. In fact, only an accelerating trend (as shown by Chris Reynolds' two piece linear trend lines) is significant. A "decelerate fit" at the end of the series is not statistically significant, and also there is no physical reason for deceleration." This is just not correct. The first breakpoint of my two trend fit is strongly supported as outlined previously in this thread. There is a second potential breakpoint in 2007. However the noise in September extent since then precludes firm conclusions as to the reality of a relaxed rate of decline or even levelling since then. That is not the same as saying that it is not there. Livina and Lenton 2013 find an abrupt change of statistics after 2007. And as DCS points out both he and Tamino seperately find suggestive evidence of a recent relaxation of trend in extent loss. Post 2007 the pack has consolidated a transition to a predominantly ice free state. First year ice has a much lower rate of thinning than does multi-year ice. Since 2010 most years have seen April PIOMAS level to around 19.3k km^3. There are physical reasons to expect a third regime of curve inflection. At this point I should make clear that I am repeating myself. I noticed that you tried to dismiss Lawrence back in 2014 in comments here (final comments). You also made the same mistake regards L&Z's findings back then as you seem to be making now (in L&Z the loss of ice is due to the albedo feedback in the ocean, not sensible warming from adjacent landmasses). So, I'm sorry, but but as I am not interested in circular discourse further discussion seems rather unproductive. I'll leave you to reply as you see fit.
Toggle Commented Jun 11, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Susan, To add to DCS, just because some of us think what happens next isn't a fast crash, that should never be taken as saying there is a recovery. Arctic sea ice is in terminal decline and anyone who says it is recovering immediately writes themselves out of informed discussion of the matter. Claims of a recovery can only be made by people with a total lack of grasp of the evidence.
Toggle Commented Jun 7, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Jim Williams, Sorry, but none of that tells us anything about the relationship between forcings and the response of the sea ice. Rob, There was a regime change in the mid 1990s, that is what that treatment of September extent is picking up. The regime change is IMO best explained by Lindsay & Zhang. L&Z find ice/ocean albedo feedback as the driver. Not snow cover. They also find a substantial increase in upward longwave associated with winter ice growth - which might explain why a linear hypothesis with a break point at 1997 seems to work rather than the (1-exp) form of exponential crash equation that might simplistically be assumed to apply. As I said above, the trend since 2007 in Sept extent is level if it's a rise or a decline (uncertainty allows either) it may not be declining at the same rate as in the preceding period. Time will increase the statistical confidence to ascertain properly what is happening post 2007. So we have a strongly demonstrated inflection of around 1997, the year after which all years of the cumulative sum of interannual differences are negative, and which ties in with the mid 1990s start of an ice/ocean albedo feedback driven decline proposed by Lindsay & Zhang. This justifies the breaking of trends and application of a piecewise linear trend around that point. That isn't the same as an exponential trend. Nor does it imply self-acceleration to zero. Eisenman has shown that previous 'toy model' studies finding a fast exponential type crash to zero lacked both seasonality (winter growth feedback) and the decline of poleward heat transport with a relaxation of the pole/equator temperature gradient. Those factors apply in the real world, so their consequences probably do too. DCS, Thanks for that, an interesting read.
Toggle Commented Jun 5, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Sorry, I forgot to add the graph of extrapolation of temperature/extent.
Toggle Commented Jun 4, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Rob, Sorry for the delay in replying, work got in the way. All of this is as a result of my looking at things from a temperature driving perspective following a recent discussion with you. I do not think that a single function applied to September NSIDC Extent is informative. If I take the interannual difference of Sept Extent then make the cumulative sum of that, the behaviour becomes apparent. Every year after 1997 is a negative cumulative sum figure, so I use that year as a break point, and there are two periods of different behaviour. Actually there are three, the post 2007 increase in variability (flat) is the third period after the 1997 to 2006 period of drop (linear). This appears in the temperature extent relationship making the plot bow around the trend line. That bowing might seem to support a non linear trend. However the early flat region is for the years before 1997,and it is certain years that pull the trend down from 2007 onwards. The presence of many mid points above the trend line is a result of the change in trend around 1997, not supportive of the application of one trend. Mahlstein & Knutti 2012 look at a large set of models. They adjust the models for known biasses and find that both the limited set of observational data and the models reach around 0 extent at approximately 2degC global warming. I am very surprised that you (and many others) persist in claiming that 2016 will be a useful year to determine what will come in the loss of sea ice. From my perspective the highly anomalous warmth over the winter invalidates any conclusions drawn from what happens this year. April Arctic Ocean sea ice volume this year was within the range I said it would return to, but I have cautioned that this winter invalidates strong assertions that it backs my case regards winter growth of ice. When such winter temperatures happen regularly, the pack will be in a far worse state than it has been following recent years (the volume increase), so what happens this summer doesn't even inform us as to the summers we can expect in future years when such winter temperatures are normal. So if we have a record summer beating 2012 I have no doubt that it will be added to data and used in exponential fits to claim support for a rapid crash. But I'm sorry, I will not find such slack reasoning convincing at all.
Toggle Commented Jun 4, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Remko, "To be sure, Arctic sea ice cannot but exist as seasonal ice at present climate conditions..." Is this the case? Obviously when one factors in the turn-around time from the current trajectory of fossil fuel dependence the sea ice is toast. But I suspect this is not what you mean. So... Is the ice response lagging or leading the driving of climate forcings? I genuinely do not know. If you don't - is there proper research on this issue? I am not aware of any. If there is no research to throw light upon the situation do we have enough data to provide an answer? And following that line of thought: 1) Is it informative that (in line with Mahstein and Knutti 2012) the relationship between global average temperature and NSIDC September Extent is linear and the extrapolation approaches 0 extent at around 2degC global average temperature anomaly (in line with Mahstein and Knutti 2012)? 2) To what degree do 2013 and 2014 and the recent volume pulse inform us of the lag or lead relationship with forcings? Here we might view a factor such a regional Arctic temperature as providing a 'wobble' on the driving signal of global temperature. 1 & 2 would suggest to me that the sea ice is in phase with climate forcings, with little lead or lag. Have I got the wrong end of the stick entirely? One way of going about this would be to calculate lead / lag correlations, but amongst a short period of data ~40 years with strong trends this is tricky. I promise not to sea-lion you on this. I've let Neil's assertion ('probably very quick') go, because I am aware I am rather bore on this. But if 'your side' (the fast crashers) are right I want to be in on the excitement. To explain - Sea Lioning...
Toggle Commented Jun 2, 2016 on Crisis in the Cryosphere at Arctic Sea Ice
Neil, I don't think it's just hindsight, we have ample precedent of satellite failure and not only in sea ice. I am aware that the operation is being done on tight budgets and setting up a shadow data stream takes time (time = money). But in my lab I have a set of kit that rarely gets used but is annually calibrated. I've just been using one such item today... We sent our main IR calibrator off for annual calibration. Somewhere in transit or at the other end, the infra-red emission plate has been severely damaged. Then whilst the wrangling over who is responsible for the damage was ongoing our secondary calibrator failed. How's that for low probability? So today I've been covering for the chap in the temperature lab (who is off on leave - how's that for probability?). And I have been using a mothballed dry well calibrator with it's block removed and the 'well' within which temperature is generated acting as an infra-red source. It's designed for such useage - that's why it's kept in working order. We have redundancy upon redundancy because whatever the ultimate causal pathways, Murphy's Law / Sod's Law is real in engineering. i.e. If it can go wrong it will, and when it goes wrong it will be at the most inconvenient moment.
Toggle Commented Jun 2, 2016 on ASI 2016 update 1: both sides at Arctic Sea Ice
John C, Sorry I forgot to reply to your post of 30 May. Yes, sometimes I am a bit vague in my phrasing. But here is the graph of Beaufort Gice thickness volumes as posted above. If we take 1995 as the start of the decline, a decision that seems reasonable in terms of Lindsay & Zhang and the running sum of interannual differences of September extent: Then we could look at pre-1995 as suggestive of the 'healthy' Beaufort. Going back to the Gice plot, first link in this post. It seems that years with low presence of very thick ice were the minority with years of high presence of very thick ice being the majority. Since 1995 years of very little multi year ice have become much more prevalent. I think the reason is a combination of summer open water formation (ice melting out) and less MYI to export from the Central Arctic.
Toggle Commented Jun 2, 2016 on ASI 2016 update 1: both sides at Arctic Sea Ice
Neil, I think we just notice it. I'm really missing not being able to baseline all my sea ice data on the same average period as my atmospheric data. It would have helped if, in anticipation of failures, NSIDC had have had the resources to run a shadow data stream of F16 and F18 along with the F17 data so they could rapidly and seamlessly transition in the event of failure of any one of the systems.
Toggle Commented Jun 1, 2016 on ASI 2016 update 1: both sides at Arctic Sea Ice