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Chris Reynolds
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Jim, Just to back up my last statement:
Toggle Commented Mar 15, 2015 on PIOMAS March 2015 at Arctic Sea Ice
Jim, The increased thickness in Baeufort seems mainly due to export from the Central Arctic. So that wouldn't affect the floe you cite. Virtually all of the volume increase is contained in the Central Arctic. So that wouldn't affect the floe you cite.
Toggle Commented Mar 15, 2015 on PIOMAS March 2015 at Arctic Sea Ice
Comparison of PIOMAS and the Arctic Basin fit from Lindsay & Schweiger 2015. Details at my blog.
Toggle Commented Mar 10, 2015 on Thinner and thinner at Arctic Sea Ice
Neven "The big question now, of course, is whether the thinning will continue at this rate or slow down. Hopefully this will become clear in years to come." This paper shows continuing thinning, as indeed does the PIOMAS data for the bulk of the Arctic - the Central Arctic region. It may be that I've called it too early in arguing that an inflection is underway from steep volume declines to less of a rate of volume decline, but on balance I think not. My claim of a 'levelling' is merely based on 2010 to 2014 April volumes, this paper only goes up to 2012 so wouldn't really help identify that in view of the noise around the trend. By 2020, just 5 years, we'll know. Cincinatus, Try here: Where there are links to data pages such as this: Some data goes back to the 1950s (IIRC), I have never had cause to use this. During the Clinton administration Al Gore arranged data to be made available to certain scientists. It was secret so I don't know whether this data is now available publicly. The secrecy was because submarine ULS transects were made to find places where missiles could be fired from nuclear submarines hiding under the ice.
Toggle Commented Mar 5, 2015 on Thinner and thinner at Arctic Sea Ice
Good post Neven. Cincinnatus, Had you bothered to check the data yourself you could have avoided making yourself look foolish.
Toggle Commented Mar 3, 2015 on Shock news! at Arctic Sea Ice
Jenny E Ross, I've just read your article on the loss of Arctic sea ice and its implications. Very well written and researched, I wouldn't disagree with any of it.
Toggle Commented Feb 20, 2015 on PIOMAS February 2015 at Arctic Sea Ice
BFraser, DavidR, I did some calculations last night. The 1975 to 1998 warming trend is greater than the 1975 to 2014 trend (about 0.016 vs 0.011degC/year IIRC). However when one treats 1998 as an outlier then the 1975 to 1997, and 1975 to 2014 trends are very similar. Sorry, I didn't keep the spreadsheet as I'm concentrating on something else right now, and by the time I get tround to blogging on other matters this will all be old news.
Toggle Commented Jan 18, 2015 on PIOMAS January 2015 at Arctic Sea Ice
Thanks Tony, I've noticed this behaviour of temperature but find it a puzzle. The time period is short and it is possible that the rough 2005 start to the levelling is two years within the range of variability around the trend, followed by a temperature response after 2007. What I'm thinking is that a lot of the warming is actually a response to the loss of sea ice, rather than the cause. From this perspective the larger open water after 2007 might cause warming in autumn and winter. Against this view is the apparent jump in 2005 to a new warm level. I've not had the time to properly get to grips with the issue yet. My view that the models are broadly right (although I expect regular virtually ice free conditions in the 2030s, not as late as the 2050s), but it not related to temperature considerations.
Toggle Commented Jan 18, 2015 on PIOMAS January 2015 at Arctic Sea Ice
Veli, How do you measure lateral viscosity? Crandles, I agree, it seems to me that it is the very act of mechanical deformation that opens up fractures and facilitates brine drainage.
Toggle Commented Jan 6, 2015 on Fram Strait 2014 at Arctic Sea Ice
Ooops, Forgot the link to the poll.
Toggle Commented Dec 10, 2014 on PIOMAS December 2014 at Arctic Sea Ice
Crandles has posted a poll on the forum asking when people think we will start to regularly see no ice (at all, as I understand it) in the Arctic Ocean, which would be during late summer. I think it would be very interesting if all forum members could vote. Note, this is for no ice at all, not virtually ice free (e.g. <1M km^2 extent). Osteopop, But there is no cessation of loss(levelling) within the Arctic Ocean, just regional effects outside the Arctic. So I see no evidence for your initial claim that: "...when the winter extent stops decreasing and even grows - what is more natural than this also affecting the summer minimum in due time?"
Toggle Commented Dec 10, 2014 on PIOMAS December 2014 at Arctic Sea Ice
Damn, didn't think I'd posted the above, while pondering how to follow up I changed my mind and did some graphs. All this is done using Wipneus's calculation of regional extent. Osteopop, Here is the decline in extent on day 90 (late March) from 1979 to 2013. I've not done the calculations, but I'd be surprised if the claimed levelling is outside the error bounds of the linear trend. That said, there might be a levelling, to examine this I break down the data into regions. First, here is the Arctic Ocean (Beaufort, Chukchi, ESS, Laptev, Kara, Barents, Greenland, Central, CAA). There is no sign of a levelling within the Arctic Ocean, why is this? I have broken down the Arctic Ocean into two subsets, land bounded seas are Beaufort, Chukchi, ESS, Laptev, Central and CAA. The Atlantic seas are Kara, Barents, Greenland, the regions most exposed to Atlantic influence. The landbound Arctic Ocean extent in March is 'maxed out' with minimal variation and negligible trend. However in the Atlantic sector, under the influence of warming Atlantic ocean waters the downward trend is significant. This Atlantic sector decline account for virtually all Atlantic ocean extent decline, and 55% of the decline slope of overall northern hemisphere extent decline for day 90. There is no evidence of a cessation in decline during recent years in the Arctic Ocean. So what of decline in the rest of the northern hemisphere? I have plotted the total extent for the northern hemisphere excluding the above defined Arctic Ocean. In this graph we see an increase in extent in the timeframe (~2005 onwards), against the long term trend, though not necessarily outside the assoicated error bounds. What is going on here? I have graphed extent for the Pacific (Okhotsk & Bering), the Atlantic (Baffin & Gulf of St Lawrence), and Hudson Bay. Hudson Bay plays no role, it is 'maxed out' by day 90 (late March). The extra-Arctic Atlantic can be viewed as having a pause in loss since 2005, while the extra-Arctic Pacific can be seen as having an uptick. So based on this I don't see any grounds for claiming that conditions within the Arctic are driving a pause in winter peak sea ice extent. Note that none of this data is hidden. The entire dataset is available here: I use "nsidc_nt_nrt_detail.txt" Wipneus has put a lot of work into producing it (I know from the work I put into my PIOMAS derived data), yet people continue to assert things without first referring to such data. When they do so they may be challenged with the data. However as it is the job of those proposing ideas to do the hard work, and as the data to do that work is available, do not be surprised if people get a bit short with your use of their time.
Toggle Commented Dec 9, 2014 on PIOMAS December 2014 at Arctic Sea Ice
Osteopop, Where is the winter maximum in extent or area set? 1) Inside the Arctic Ocean. or 2) Outside the Arctic Ocean.
Toggle Commented Dec 9, 2014 on PIOMAS December 2014 at Arctic Sea Ice
The oceans are acidifying. Therefore the oceans are not the source of the increase in atmospheric CO2. When I was a sceptic such trash was doing the rounds, I am amazed to see it is still being claimed, especially when sceptics (well he was one when I was one) such as Ferdinand Engelbeen have thoroughly destroyed the argument and demonstrated how the CO2 increase is man made. The correlation between CO2 and sea ice is with global CO2, not local CO2 levels above the ice. Inertia isn't a bad analogy, but what is actually happening is latency caused by energy storage. It takes time for land and ocean to warm causing a lag behind insolation in the annual cycle. Strictly speaking inertia refers to a mechanical effect, but there is the term 'thermal inertia'.
Toggle Commented Dec 9, 2014 on PIOMAS November 2014 at Arctic Sea Ice
I forgot to add to the above. Whilst there may be something subtle that indicates a common cause to the weather patterns of summer 2013 and summer 2014, the largescale pattern doesn't seem to me to indicate a common new pattern due to a regime shift. Jun to Aug 2013 Jun to Aug 2014
Toggle Commented Dec 8, 2014 on PIOMAS December 2014 at Arctic Sea Ice
I've had to correct the regional volume graph at the start of my blog post. The data displayed reverted to September data after copy and paste - odd Excel bug. Osteopop, You tend to favour a shift that drives a reverse of sea ice loss because, as amply demonstrated in the past, you are driven by an agenda which dictates your conclusions. I do not have enough information to say either way whether a changed of typical summer atmospheric regime is starting. I think we will know in a few years if summer considitions continues to be adverse to ice loss. However, given that sea ice extent loss is so clearly correlated with increases in CO2. And given that the loss of volume from 1995 to 2012 has been driven by the ice/ocean albedo feedback. And given the wide variety of weather that has not led to a recovery of the summer sea ice. The conservative position remains that the process of sea ice loss will continue. Although of course I think we will enter a long(ish) tail of persistence of the summer sea ice that is not implied by statistical extrapolation of volume loss.
Toggle Commented Dec 8, 2014 on PIOMAS December 2014 at Arctic Sea Ice
Iceman, To be clear, what is going on with volume at present is not, in my opinion, part of the emergence of a long(ish) tail of the 'sigmoid' form. The last two years of poor summer melt weather could have happened at any time in the last ten years or so and have had a similar effect. That weather issue is seperate from my argument that winter volume had hit a floor with a slower rate of volume loss dictated by the tending of winter thickness to the thickness of thermodynamic growth (roughly 2m thick ice). As I have said before, actually it's a nuisance for me because I will probably have to wait several more years for the floor in winter volume to be regained.
Toggle Commented Dec 7, 2014 on PIOMAS December 2014 at Arctic Sea Ice
DrPhilosopher, and Note that the second plot in the above image shows irradiance and sea ice, from that plot one would come to the conclusion that a higher level of insolation leads to more sea ice, this is obviously absurd. This relationship happens because the decline in sea ice driven by human activities has happened as solar insolation has fallen as we have left the Grand Solar Maximum of the mid to late 20th century. As JD Allen points out, the insolation decline will have little effect. Those above images are from these two sources (in order). Johannessen 2008, "Decreasing Arctic Sea Ice Mirrors Increasing CO2 on Decadal Time Scale." Notz & Marotzke, 2012, "Observations reveal external driver for Arctic sea-ice retreat" In the following image of model runs the coloured lines include anthropogenic forcings, the grey lines don't. Put simply, without human impacts there is no decline of sea ice. That image is from Wang & Overland, 2012, A sea ice free summer Arctic within 30 years? - CMIP5 Update.
Toggle Commented Nov 22, 2014 on PIOMAS November 2014 at Arctic Sea Ice
Wayne, We'll know over winter if PIOMAS is correct as Cryosat and IceBridge data comes out. Personally I have no doubt PIOMAS is reflecting increased thickness and volume correctly. Susan, Thanks for that.
Steve, Sounds like it may be pushing the strict definition, but Neven's appearance at the SIPN conference, and the use of graphs published here by commenters may swing the decision should Neven want to nominate you (given that he's on another continent. If you were to go I'd look forward to your posts. And I agree you're grounded enough in the science to do a good job.
Toggle Commented Oct 28, 2014 on PIOMAS October 2014 at Arctic Sea Ice
Thanks for the post Neven, and thanks for the recommendations. David Appell, Thanks I wasn't aware of that meeting. Average volume for all days 1979 to 2012 is 20.47k km^3, 1/6 of that is 3.41k km^3. Summer is a bit hard to pin down (does it include September?), JJA average volume for 2012 was 10.00k km^3, JAS average was 5.96k km^3. So the scenario painted is a sort of super 2012 situation. However in a model experiment involving PIOMAS that Dr Blanchard Wigglesworth asked for a reduction of early spring ice thickness by 1m resulted in a very aggressive spring melt, and the remnant thicker ice off northern Canada surviving through the summer. So it looks like such a situation. The extreme low volume not implying totally ice free in September, but a rapid spring loss followed by a reduced late summer rate of volume loss. The following is a screenshot of the presentation. Left column is 'control' typical behaviour for recent years. Right column is 'experiment' the result of the artificial thinning of ice. Months from June to September go down the columns. From here: Hat tip to Crandles. :)
Toggle Commented Oct 9, 2014 on PIOMAS October 2014 at Arctic Sea Ice
"Wow, over 100 comments, might be something interesting about Arctic sea ice in all that", thought I. Vinyards? Back to the forum, nothing interesting going on here.
John, If you're right (the 'if' is not meant to cast doubt, it just means I don't know), then you use the appropriate tool for the job. And in your case the NAO seems appropriate.
Toggle Commented Sep 13, 2014 on PIOMAS September 2014 at Arctic Sea Ice
John Christensen, Hurrell, 2000, Climate: North Atlantic and Arctic Oscillation (NAO/AO). Extract from the Encyclopedia of Atmospheric Science - used in place of the peer reviewed paper I can't find at present. "That the NAO and AO reflect essentially the same mode of tropospheric variability is emphasized by the fact that their time series are nearly identical, with differences depending mostly on the details of the analysis procedure." Or checking in my Favourites I find a link to this page: "It follows that the NAO and AO are synonyms: they are different names for the same variability, not different patterns of variability. The difference between the terms is in whether that variability is interpreted as a regional pattern controlled by Atlantic sector processes or as an annular mode whose strongest teleconnections lie in the Atlantic sector." Figure 1 on that page is an amusing summary of the relationship.
Toggle Commented Sep 12, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Blaine, The problem I am having is as follows: 1) I have read multiple references in papers, granted mainly winter, if I recall correctly, to AO/NAO like patterns. The formation of the AO/NAO patterns by land/sea masses is likely to apply to other patterns driven by various factors related to Arctic climate change. Yes the 2007 to 2012 summer pattern is like the AO/NAO, but I view it as significantly different enough to justify viewing it differently. 2) The AO/NAO has not in the past driven strong Dipole like behaviour within the Arctic. 3) The AO/NAO has not in the past been associated with the unusually high geopotential heights seen over Greenland. 4) 2007 to 2012 all fall within the eleven lowest NAO indices for June July August. Excluding 2014 from the 2007 and 2012 due to its complication. Here is average SLP for 2007 to 2012. Here is average SLP for the ten lowest NAO years excluding 2007 to 2012. I've presented these as averages, not anomalies as some have complained about the 1980 to 2010 anomaly period partly covering 2007 to 2012. The shift to a more Greenland centred behaviour after 2007 seems clear to me. Needless to say, similarity in the Pacific and Atlantic is irrelevant as this is topographically driven, and topography has not changed. Yes the AO/NAO are essentially the same thing. I use the AO because it reflects Arctic Ocean dominant pressure. Summer Pattern Correlation. I've resorted to using correlation because my maths aren't up to PCA, which would have been a preferred method. June July August 1979 -0.440 -0.297 0.386 1980 -0.081 0.738 -0.262 1981 0.516 -0.389 -0.571 1982 0.724 -0.539 0.023 1983 -0.800 -0.134 -0.272 1984 -0.048 -0.114 -0.588 1985 0.249 0.265 0.446 1986 -0.670 -0.081 0.250 1987 0.721 0.209 0.486 1988 -0.557 0.485 -0.241 1989 -0.639 -0.695 -0.032 1990 0.015 -0.334 0.478 1991 0.016 -0.197 -0.862 1992 -0.232 -0.499 -0.388 1993 0.285 0.382 0.048 1994 -0.797 -0.622 -0.442 1995 -0.400 0.657 -0.157 1996 -0.654 -0.733 -0.340 1997 0.795 0.252 -0.600 1998 0.669 0.147 -0.261 1999 -0.636 0.399 0.680 2000 -0.181 0.140 -0.097 2001 -0.304 0.189 -0.166 2002 -0.576 -0.489 0.179 2003 0.254 -0.088 -0.423 2004 0.382 -0.557 0.475 2005 0.463 0.260 0.386 2006 -0.682 -0.097 0.027 2007 0.725 0.759 0.532 2008 0.612 0.774 0.567 2009 0.685 0.784 0.436 2010 0.660 -0.405 0.639 2011 0.787 0.788 0.824 2012 0.633 0.316 0.459 2013 -0.755 -0.126 -0.463 2014 0.470 0.394 0.656 Correlations with NAO by month. Jun Jul Aug 1979 to 2014, -0.870, -0.657, -0.517 2000 to 2014, -0.837, -0.780, -0.580 1979 to 2006, -0.857, -0.574, -0.288 Note the drop in correlation through the summer when the post 2007 period is excluded. However I will defer to your expertise and desist from mentioning the matter again. I'm busy enough with sea ice and the day job.
Toggle Commented Sep 11, 2014 on PIOMAS September 2014 at Arctic Sea Ice