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Rob Dekker
California
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Jim Hunt wrote Whilst I do appreciate that people publicly peddling porky pies do need to be publicly corrected, do you think it might be possible to try and stick to the Arctic/Antarctic theme in here? I'll try to restrain myself, but when disinformation pops up, that's hard. Either way there is a good thread on the forum that discusses more details, if (the other Jim) would like to continue the conversation : "Cars, cars and more cars. And trucks, and...." https://forum.arctic-sea-ice.net/index.php/topic,438.msg136297.html#msg136297
Toggle Commented Dec 15, 2017 on PIOMAS December 2017 at Arctic Sea Ice
Jim said : The idea that electric cars will save us from CO2 is a pet peeve of mine. Rather then rant about the issues here is a very good blog post that describes the problem: http://www.aviewfromthecyclepath.com/2017/09/business-as-usual-by-driving-green-car.html When comparing carbon intensity of ICE cars to EV, if they come out about even, you ALWAYS have to check the facts. As in this case too. Your link tells about the original Mini : Burning a litre of petrol results in 2.3 kg of CO2 being released, hence a gallon results in 10.4 kg of CO2 or as it is usually expressed these days, 162.5 g/km. and about the Leaf : The Leaf requires 12.4 kWh of electricity to cover 64 km, and that results in 155 g/km of CO2 if the car is charged from the Dutch electricity network. Now, we can argue if the original Mini and the Leaf are comparable automobiles (one could argue that the Mini is a Mr.Bean car where you can only comfortably drive it if you are sitting on the back seat). And we can argue if the 12.4 kWh for 64km is comparable, since EVs have a much better efficiency in city traffic than ICE vehicles. But even with all that assumed equal, there is still a BIG problem with this story : That 12.4 kWh causing 155 g/km data is not referenced anywhere. So I did some digging myself and found this scientific paper : https://www.sciencedirect.com/science/article/pii/S1361920916307933 That one clearly states that on the Dutch grid, the carbon intensity of supplied electricity is about 547 g/kWh. For 12.4 kWh that is 6.782 kg CO2, spread over 64 km is 106 g/km. That is some 40% better than the Mini on petrol. And since the Netherlands is phasing out coal and increasing wind/solar, that number will only get better over time. Fact checking rules.
Toggle Commented Dec 14, 2017 on PIOMAS December 2017 at Arctic Sea Ice
DCS, I hope you are right.
Toggle Commented Nov 30, 2017 on PIOMAS November 2017 at Arctic Sea Ice
The question is especially important, since so far the statistical evidence suggests that 'volume' loss is still accelerating : https://sites.google.com/site/arctischepinguin/home/piomas
Toggle Commented Nov 28, 2017 on PIOMAS November 2017 at Arctic Sea Ice
DCS said : In light of the content of some of my comments under the previous article, I’m projecting a significant deceleration in the decline of Arctic sea ice volume, if that hasn’t already happened. You seem to advertise the theory that summer heat melts only 'area', not 'volume'. Do you have any evidence that that "already happened" ?
Toggle Commented Nov 28, 2017 on PIOMAS November 2017 at Arctic Sea Ice
That's good work DCS. Thank you ! You even made both A''(t) and T''(t) negative. It's still a mathematical exercise though. If this scenario will pan out in real time or not will depend on the bigger question : Will summer heat melt 'volume' or will it melt 'area'. If it melts area than you will be right and volume will decelerate. But if it melt volume then volume will just go down (linearly) and at some point, as Wadhams stated before : "In the end, it will just melt away quite suddenly". Area that is.
Toggle Commented Nov 26, 2017 on PIOMAS October 2017 at Arctic Sea Ice
DCS said Proof: Assume that A(t) and T(t) are each continuous and twice differentiable. Note that V = A T. Then V'(t) = A(t) T'(t) + A'(t) T(t), and V''(t) = A(t) T''(t) + 2 A'(t) T'(t) + A''(t) T(t). Assume that A(t) > 0, A'(t) < 0, A''(t) ≥ 0, T(t) > 0, T'(t) < 0, and T''(t) ≥ 0. Then A(t) T''(t) ≥ 0, 2 A'(t) T'(t) > 0, and A''(t) T(t) ≥ 0. It follows that V''(t) > 0 and that the decline in V is decelerating. You don't know if A''(t) ≥ 0 nor do you know if T''(t) ≥ 0. You are just assuming that. So what remains is your statement : "If Arctic sea ice volume were to decelerate significantly (which I'm expecting, maybe that is wishful thinking) "
Toggle Commented Nov 25, 2017 on PIOMAS October 2017 at Arctic Sea Ice
D_C_S, you did not read that article all the way to the end.
Toggle Commented Nov 14, 2017 on PIOMAS October 2017 at Arctic Sea Ice
Excellent post by Tamino : for anyone who thought that Arctic sea ice decline slowed down after 2007 : https://tamino.wordpress.com/2017/11/02/cycle-change-arctic-sea-ice-edition/ I’d like to congratulate all the readers who have read the last two posts. You now know a helluva lot more about Arctic sea ice and how it has changed, than most people. You know: - It has declined dramatically - The decline has not recently stopped or even slowed. - The decline isn’t just a summer/fall annual minimum thing; it has declined throughout the entire year. - The annual minimum decline dropped steeply in 2007. - The geometry of the continents (of land areas in general) affects the relationship between the sea ice edge latitude and its extent. I’d guess that you are now prepared to discuss the issue intelligently. I’ll opine that you are far better prepared to discuss it intelligently than any of those who have recently been claiming it isn’t still declining.
Toggle Commented Nov 11, 2017 on PIOMAS October 2017 at Arctic Sea Ice
Hans said about my (5.4) prediction of the average NSIDC September extent : Let's say we're determining if a prediction is accurate by way of using the Sept. average, but since that is more forgiving, let's say the range of accuracy needs to be within .25 million square kilometers, then .5 is double that standard and thus inaccurate. You are right that my prediction is not accurate. In fact, it will probably be more in the range of 4.8 - 4.9. We will see at the end of September. Note though that this was a June prediction, and the standard deviation of that prediction is about 350 k km^2. So 4.8 - 4.9 is still well within the 95% uncertainty margin. Also, there is an identifiable reason why my prediction was too high : My method does not include ice thickness, which was low this year due to the anomalously warm winter. Lewis did a good piece on that : http://neven1.typepad.com/blog/2017/08/guest-blog-arctic-prediction-models.html Either way, I do think my prediction method is not good enough yet. And I'm looking for better early indicators that can improve the model.
Toggle Commented Sep 26, 2017 on PIOMAS September 2017 at Arctic Sea Ice
Hans, About this polynya, I presented a different theory, that it may be caused by the Coriolis forces driving the Atlantic warm water upward while making a U-turn at that very location against the Gekkal Ridge : http://forum.arctic-sea-ice.net/index.php/topic,1834.msg125728.html#msg125728
As Wipneus reports on the ASIF : According to NSIDC NT sea ice concentration, extent in 2017 is currently the 8th lowest, area is 7th. Looks like we are not going to see any records broken this year.
Lewis, thanks. One point of clarification : I include land snow cover in my model since it clearly affects albedo and thus the heat budget over the Northern Hemisphere. Snow on ice affects the albedo much less and thus in my opinion is not that important for the heat budget.
Thank you Lewis, for this nice overview of prediction models. Early in the melting season, we saw this large negative anomaly of volume, which was caused by an exceptionally warm winter. Luckily, the summer registered a rather cool melting season, which I think is partially caused by that large positive land snow anomaly that Rutgers Snow land recorded : http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6 Some 4 million km^2 of land snow more in June than last year. That has got to leave a significant dent on absorbed heat in the Northern Hemisphere. So I think that the negative volume anomaly in winter and the positive land snow anomaly in summer balanced each other out and we end up with a September SIE that is neither exceptionally low nor exceptionally high. Other years we may not be so lucky.
When you look at the images I posted, it will tell to upgrade the photobucket account to one that supports 3rd party hosting. Photobucket charges $400/year for that and I'm not going to pay that amount of money. So, to look at the images I posted, right-click the image and open in a new window. Thanks !
I find it fascinating to see how low volume makes conventional wisdom (with regards to the influence of weather conditions on extent decrease) partially moot. I remember noticing it for the first time in 2012. Yes. We will probably never know how close to total oblivion we came in 2012, but it may have been pretty darn close. And now in 2017, with most of the major indicators (land snow cover, ice concentration, and ice 'area') suggesting a 2013/2014 'recovery' year was in the works, while 'extent' is still running close to record low, it is blatantly clear that we have dodged a canon ball as you suggested before.
Toggle Commented Aug 11, 2017 on PIOMAS August 2017 at Arctic Sea Ice
Incidentally, in that image, you can also see the 'dipole' that has been dominating the 2017 summer.
Toggle Commented Aug 11, 2017 on PIOMAS August 2017 at Arctic Sea Ice
OK, it looks like 'photobucket' wants me to pay $400/year to be able to post images from my photobucket library. I am not amused, since I've been posting a LOT of such images over years in the ASIB comment sections (including the ones I really care about, like the 1935-2014 thread. Some $10/year would be OK. But $400 is just ridiculous. Let me see what I can do with the old images, but for now, here is the NCEP/NCAR spacial image that belongs in my previous comment :
Toggle Commented Aug 11, 2017 on PIOMAS August 2017 at Arctic Sea Ice
DavidR said : According to the NOAA-ESRL measurements 2017 has been colder than 2013 and 2014 in both the Arctic and the high Arctic (80N+) over most of the May - Jul period and on average. Thanks David, for pointing this out ! As for the where this 'cold' resided during this summer, here is the NOAA spacial plot (May-July, 60-90deg) : Note that the cold was most intense around the Laptev shoreline, incidentally the same location where the land snow lasted longest, and created that significant land snow anomaly this June : http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6
Toggle Commented Aug 11, 2017 on PIOMAS August 2017 at Arctic Sea Ice
Hi Bill, On July 5 you posted the September SIE numbers using the 'daily average' method as opposed to the standard NSIDC method of calculation. On the Forum you asked me to run these numbers through my method to see if the 'daily average' method is better 'predictable'. I just posted the results on the forum here : http://forum.arctic-sea-ice.net/index.php/topic,1834.msg121896.html#msg121896 Result is that no, the 'daily average' method is not better predictable than the standard NSIDC SIE numbers. However, NSIDC 'area' numbers ARE better predictable, obtaining a beautiful 270 k km^2 SD of the residuals. That method still predicts that 2017 will end up where 2013 and 2014 were, so it still predicts a 'rebound' year. But, as noted above, we really should be starting to see a major 'stall' in SIE decline really soon now for that prediction to remain somewhat believable...
Toggle Commented Jul 23, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
2017 is still dropping rapidly, keeping pace with 2007 and 2012. If this continues much longer then my hypothesis that June land snow cover and ice concentration are a good predictor for September SIE will be debunked.
Toggle Commented Jul 15, 2017 on Melting momentum: May 2017 at Arctic Sea Ice
P-maker, back in the 80's, in June the melt line would be outside the Arctic Basin, where there is no MYI.
Toggle Commented Jul 15, 2017 on PIOMAS July 2017 at Arctic Sea Ice
I have another theory, and one we can possibly test : Notice that the reduction in volume loss since the 80's happens mostly during July (see Wipneus' "Arctic Ice Volume Anomaly" graph here) : https://sites.google.com/site/arctischepinguin/home/piomas And remember that in recent years, July is when the melt starts to eat seriously into the Arctic Basin, which during the 80's the melt line was still outside the Basin. So if PIOMAS underestimates the thickness of ice in the periphery of the Arctic Basin (and possibly overestimates the thickness of ice outside the Basic), then PIOMAS would record less ice loss during July in recent years, compared to earlier decades. The estimate does not need to be much : just a 20% error in thickness would explain the (PIOMAS recorded) reduced ice volume melt during July. Does that make sense ?
Toggle Commented Jul 15, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Excellent points, D. Thinner ice could indeed imply increased sensitivity on insolation. That could explain the rapid decline of volume during June of the recent years that is so clearly visible in Wipneus' volume anomaly graphs : https://sites.google.com/site/arctischepinguin/home/piomas But that still does not explain why volume loss in the second half of the melting season (July to September) is actually less than in the 80's.
Toggle Commented Jul 14, 2017 on PIOMAS July 2017 at Arctic Sea Ice
Sorry guys, I'm not sure about that last claim. I'm not sure which year had the least volume loss since the start of July through September. Yet the first claim (that volume loss seems to decrease over time) still stands.
Toggle Commented Jul 13, 2017 on PIOMAS July 2017 at Arctic Sea Ice