1
Arctic sea ice / Re: Arctic Image of the Day
« on: Today at 03:08:47 AM »
https://phys.org/news/2021-01-climate-carbon-trends-million-years.html
It's not current news being from 2006, but it's still a lovely picture.
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https://phys.org/news/2021-01-climate-carbon-trends-million-years.html
It's not current news being from 2006, but it's still a lovely picture.
2
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: January 22, 2021, 09:47:07 PM »
Back in November, I posted a chart showing predicted end-of-year 2020 annual NASS GISS-Temp (global average surface temperature) anomaly vs. 1850-1900 average AFTER removing short-term influences of ENSO (El Nino/La Nina), solar cycle, and aerosol (Mauna Loa). The final two months of 2020 came in slightly warmer than expected. Here is how 2020 looks with all 12 months of NASA GISS values.
The observed 2020 value was a statistical tie with 2016 (with 2020 at 0.014 C warmer) as the warmest year in modern record (since 1880). But when you subtract out temporary influences of ENSO/solar/aerosol, to estimate an underlying systemic temperature, then 2020 was the warmest year by a larger margin. 2020 was 0.109 C warmer than 2019, which replaces 2016 in 2nd place when you filter out the estimated effects of ENSO/solar/aerosol.
In the Real Climate blog, Gavin Schmidt of NASA says the uncertainty in the annual GISS-Temp annual anomaly is 0.05C. The uncertainty for estimates that include additional factors (ENSO/solar/aerosol) each with its own uncertainties is probably larger. But at least Schmidt's 0.05 uncertainty for annual GISSTemp anomaly gives us a frame of reference.
At 0.109 C warmer than the previous warmest year, it seems likely that 2020 was indeed the warmest year in the modern record. Schmidt also said that the estimate of global average surface temperature itself has an uncertainty of ca. 0.5C, so this conclusion may be a distinction without a meaningful difference. Especially when you remember that the surface temperature does not equal the temperature of the planetary system as whole. There is a lot more heat energy stored in the ocean than in the atmosphere. But for tracking the climate change influence driving Arctic Sea Ice, the NASA GISSTemp may be as good an indicator as any (says a guy with no training in climate science).
The observed 2020 value was a statistical tie with 2016 (with 2020 at 0.014 C warmer) as the warmest year in modern record (since 1880). But when you subtract out temporary influences of ENSO/solar/aerosol, to estimate an underlying systemic temperature, then 2020 was the warmest year by a larger margin. 2020 was 0.109 C warmer than 2019, which replaces 2016 in 2nd place when you filter out the estimated effects of ENSO/solar/aerosol.
In the Real Climate blog, Gavin Schmidt of NASA says the uncertainty in the annual GISS-Temp annual anomaly is 0.05C. The uncertainty for estimates that include additional factors (ENSO/solar/aerosol) each with its own uncertainties is probably larger. But at least Schmidt's 0.05 uncertainty for annual GISSTemp anomaly gives us a frame of reference.
At 0.109 C warmer than the previous warmest year, it seems likely that 2020 was indeed the warmest year in the modern record. Schmidt also said that the estimate of global average surface temperature itself has an uncertainty of ca. 0.5C, so this conclusion may be a distinction without a meaningful difference. Especially when you remember that the surface temperature does not equal the temperature of the planetary system as whole. There is a lot more heat energy stored in the ocean than in the atmosphere. But for tracking the climate change influence driving Arctic Sea Ice, the NASA GISSTemp may be as good an indicator as any (says a guy with no training in climate science).
3
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: January 19, 2021, 03:36:05 PM »
Are there different terms/names to distinguish between
1) broad retreat of CAB ice along the Atlantic front interface with Greenland, Barents, and Kara Seas
vs.
2) Atlantic water intrusion along the Siberian coast, now reaching into the ESS and perhaps the Chukchi Sea?
My understanding is that "Atlantification" refers to #2. If so, what is the name for #1?
"CAB-Atlantic side retreat"?
Whatever it is called, the Atlantic side of CAB looks weak at present. But in previous cases, Arctic variability has led me to believe that a large change was underway only to see the ice revert closer to "normal" later. And even if Atlantic side of CAB is weak at present, there are 2-3 months of strong freezing and ice increase remaining this winter. And last time I looked, the CAB volume statistics did not seem remarkably low.
Of course, the long term trend downward to less ice is indisputable. But for today, the question is does the current amount, thickness and/or concentration of ice in the CAB along the Atlantic front appear to be significantly different from previous recent years?
1) broad retreat of CAB ice along the Atlantic front interface with Greenland, Barents, and Kara Seas
vs.
2) Atlantic water intrusion along the Siberian coast, now reaching into the ESS and perhaps the Chukchi Sea?
My understanding is that "Atlantification" refers to #2. If so, what is the name for #1?
"CAB-Atlantic side retreat"?
Whatever it is called, the Atlantic side of CAB looks weak at present. But in previous cases, Arctic variability has led me to believe that a large change was underway only to see the ice revert closer to "normal" later. And even if Atlantic side of CAB is weak at present, there are 2-3 months of strong freezing and ice increase remaining this winter. And last time I looked, the CAB volume statistics did not seem remarkably low.
Of course, the long term trend downward to less ice is indisputable. But for today, the question is does the current amount, thickness and/or concentration of ice in the CAB along the Atlantic front appear to be significantly different from previous recent years?
4
Arctic sea ice / Re: Arctic Image of the Day
« on: January 12, 2021, 11:20:50 PM »
Gorgeous photography along with sobering and very well presented summary of Arctic sea ice and other aspects of albedo contribution to climate change. One of a series of five 9-14 minute films on climate feedbacks at https://feedbackloopsclimate.com/.
Easy to get so focused on the numbers that we forget the beauty at stake. These films capture some of the beauty. The films also provide expert commentary (Jennifer Francies, Kerry Emmanuel and others) with very simple but powerful analogies to carry the message. The films are in English, with subtitles in 20 languages.
Easy to get so focused on the numbers that we forget the beauty at stake. These films capture some of the beauty. The films also provide expert commentary (Jennifer Francies, Kerry Emmanuel and others) with very simple but powerful analogies to carry the message. The films are in English, with subtitles in 20 languages.
5
Arctic sea ice / Re: What's new in the Arctic ?
« on: January 07, 2021, 04:10:53 PM »
The end-game begins through the Nares Strait?
"Ice arches holding Arctic's 'last ice area' in place are at risk, researcher says"
https://phys.org/news/2021-01-ice-arches-arctic-area.html
Excerpts -------
But recent research at the University of Toronto Mississauga suggests the last ice area may be in more peril than previously thought. In a recent paper published in the journal Nature Communications, Professor Kent Moore and his co-authors describe how this multi-year ice is at risk not just of melting in place, but of floating southward into warmer regions. This, in turn, would create an "ice deficit" and hasten the disappearance of the last ice area.
"The last ice area is losing ice mass at twice the rate of the entire Arctic," Moore says. "We realized this area may not be as stable as people think."
His most recent analysis of satellite data says the problem may be getting even worse. The arches along Nares Strait that historically have held the Last ice Area in place have become less stable, according to the study.
"The ice arches that usually develop at the northern and southern ends of Nares Strait play an important role in modulating the export of Arctic Ocean multi-year sea ice," he and his authors write.
Ice arches only form for part of the year. When they break up in the spring, ice moves more freely down the Nares Strait. And that breakup is happening sooner than in the past.
"Every year, the reduction in duration is about one week," (emphasis added by GK) Moore says. "They used to persist for about 200 days and now they're persisting for about 150 days. There's quite a remarkable reduction.
"We think that it's related to the fact the ice is just thinner and thinner ice is less stable."
More information: G. W. K. Moore et al. Anomalous collapses of Nares Strait ice arches leads to enhanced export of Arctic sea ice, Nature Communications (2021). DOI: 10.1038/s41467-020-20314-w
"Ice arches holding Arctic's 'last ice area' in place are at risk, researcher says"
https://phys.org/news/2021-01-ice-arches-arctic-area.html
Excerpts -------
But recent research at the University of Toronto Mississauga suggests the last ice area may be in more peril than previously thought. In a recent paper published in the journal Nature Communications, Professor Kent Moore and his co-authors describe how this multi-year ice is at risk not just of melting in place, but of floating southward into warmer regions. This, in turn, would create an "ice deficit" and hasten the disappearance of the last ice area.
"The last ice area is losing ice mass at twice the rate of the entire Arctic," Moore says. "We realized this area may not be as stable as people think."
His most recent analysis of satellite data says the problem may be getting even worse. The arches along Nares Strait that historically have held the Last ice Area in place have become less stable, according to the study.
"The ice arches that usually develop at the northern and southern ends of Nares Strait play an important role in modulating the export of Arctic Ocean multi-year sea ice," he and his authors write.
Ice arches only form for part of the year. When they break up in the spring, ice moves more freely down the Nares Strait. And that breakup is happening sooner than in the past.
"Every year, the reduction in duration is about one week," (emphasis added by GK) Moore says. "They used to persist for about 200 days and now they're persisting for about 150 days. There's quite a remarkable reduction.
"We think that it's related to the fact the ice is just thinner and thinner ice is less stable."
More information: G. W. K. Moore et al. Anomalous collapses of Nares Strait ice arches leads to enhanced export of Arctic sea ice, Nature Communications (2021). DOI: 10.1038/s41467-020-20314-w
6
Arctic sea ice / Re: The 2020/2021 freezing season
« on: January 04, 2021, 03:21:44 AM »How close to the surface does the subsurface warm water become vulnerable to release to the surface from a strong storm?...whoi itp120That temperature profile is very, very strange, and quite disturbing. Upwelling or intrusion from elsewhere, but strange, if not local, that a layer like that would slide along just under the top 25m of cold near-surface water.
The implied availability of local heat is significant.
7
Arctic sea ice / Re: What the Buoys are telling
« on: December 31, 2020, 05:04:06 AM »Definitely looks like it depends on the year (and where the buoys are)
At risk of being a pain, instead of single year summaries for the buoy tracks, is it possible to show 3-year or 4-year cumulative track summaries? Most of the annual tracks are too short to see if anything like a trip around a gyre results. 2007 and 2009 show the closest match to what a presumed Beaufort Gyre would look like, but the others are just segments.
My visual impression from the excellent work by uniquorn and SimonF92 to show "where the buoy's are" (~~ doop doo doo-wah!~~
), is that the buoy tracks in the aggregate are far too variable to summarize into a consistent pattern like the flushing of a toilet bowl. (I hate to think what would result if my toilet's drainage was as feebly organized as the buoy tracks seem to be). The Transpolar Drift and Fram Export show up in the buoy travel paths loud and clear, but not the famed BG. The observation that ASI would migrate around in the Pacific side of the ocean for multiple years (or at least it used to before what were ice growth nursery areas became summer melting zones) all the while building thickness across those years can hold true without needing to invent a thing called the Beaufort Gyre to concretize that process into a specific travel pattern that does not exist. Thus the resulting effect from a Beaufort Gyre type pattern as an ice accumulation process seems like an accurate concept. But as for the existence of the Gyre itself, I don't see it. I may have to retract my chiding A-Team about being too fussy about terminology. I agree with A-Team, either show up with data to define what you mean by the Gyre or stop talking about it like it's a thing. Because until there are data, there is no there, there.
It looks to me like the term Beaufort Gyre should be replaced by the less catchy but possibly more accurate term "Pacific sector of the larger Transpolar Drift pattern". I mean I think there is a loose pattern of ASI moving from the Beaufort towards the Chukchi and then towards the ESS and Laptev and then northward. But to say that those buoys moving like drunken ants are dancing "The Beaufort Gyre" as if it was the Viennese Waltz, or as if they were the Ohio State University marching band creating elegant choreography on the football field at half-time, credits them with way more organizational skill than they deserve.
The 2020 track summary does seem to indicate that the MOSAIC expedition planning team just happened to pick the one year to drift with the ice when the 'Fram Export' became the 'Fram Freight Train Express' and so got spit out the other side a lot faster than expected. Or maybe they picked the first year of the new Arctic ice transport pattern that is the new normal from now into the future (for as long as there is ASI to drift).
More dumb questions: In some of the post-2001-2010 animations there are buoy positions in the summer in areas of the ESS/Laptev that seem likely to have melted out by those dates. You may have explained this elsewhere, but are all the tracks supposed to be ice-embedded buoys? Or are some of the buoy tracks from units floating in open water and thus subject to an entirely different set of influences from ocean and/or wind currents? As Oren pointed out, the famed (but fading fast in my eyes) Beaufort Gyre only refers to ice pack movement, right?
Even dumber perhaps: What is going on with the tracks that zoom off in a straight line at an absurd speed? Are there aliens stealing our ice buoys? In doing a summary, it would be good to filter those buoys out of any average track values.
Thanks for all the work you guys have done on this (esp. uniquorn who has been beating this drum for as long as I can remember). It looks like it must take a lot mouse clicks and squinting at rows of numbers on the screen to create these excellent visualizations that the rest of us get to enjoy and learn from.
8
Arctic sea ice / Re: What the Buoys are telling
« on: December 31, 2020, 04:26:45 AM »Something like this, but averages?
Definitely looks like it depends on the year (and where the buoys are)Yes, those are great! As uniquorn said, summary arrows on the color blotch summary would be perfect. The color scaling shows motion in the CAA and Beaufort Sea areas, but if the arrows show little directionality, that doesn't fit there being much "Gyreocity". My guess is that there will be some directionality in the expected directions, but the rather scattered and low velocities indicated by the large amount of purplish (and thus near zero) coloration is not impressively coherent. The name "Beaufort Gyre" gives the impression of some vast coherent whirlpool, even if it takes 3 or 4 years to make loop. The velocity color summary does not look very organized or coherent, or at least not enough to deserve a proper name as if it were some beast prowling the Arctic Ocean.
9
Arctic sea ice / Re: Arctic Image of the Day
« on: December 30, 2020, 12:46:03 AM »
I like the visual alliteration of the street lights with the moon. I hope the guy with the open door house is snuggled in bed with his Yeti girlfriend.
10
Arctic sea ice / Re: What the Buoys are telling
« on: December 30, 2020, 12:21:03 AM »
RE The buoy travel animations.
Over in the MOSAIC thread, A-Team questions whether the famed Beaufort Gyre (BG) is really a thing. He includes a variety of proposed definitions of what the BG pattern supposedly is, implying that there is no real defined pattern, just a bunch of different observations that our human tendency to see patterns imagines into existence as an entity.
Image below is from A-Team post at [https://forum.arctic-sea-ice.net/index.php/topic,2906.msg296095.html#msg296095
If you put all the buoy track animations on top of each other and boil them down to an average motion, do you get a set of summary arrows similar to any of those proposed BG tracks? For example, does the net buoy travel follow something like the image below? After watching uniquorn's animations I am more inclined to see what A-Team means by saying there really is not enough of a distinct pattern to justify naming a thing called the "Beaufort Gyre."
Over in the MOSAIC thread, A-Team questions whether the famed Beaufort Gyre (BG) is really a thing. He includes a variety of proposed definitions of what the BG pattern supposedly is, implying that there is no real defined pattern, just a bunch of different observations that our human tendency to see patterns imagines into existence as an entity.
Image below is from A-Team post at [https://forum.arctic-sea-ice.net/index.php/topic,2906.msg296095.html#msg296095
If you put all the buoy track animations on top of each other and boil them down to an average motion, do you get a set of summary arrows similar to any of those proposed BG tracks? For example, does the net buoy travel follow something like the image below? After watching uniquorn's animations I am more inclined to see what A-Team means by saying there really is not enough of a distinct pattern to justify naming a thing called the "Beaufort Gyre."
11
Arctic sea ice / Re: What the Buoys are telling
« on: December 29, 2020, 06:13:33 PM »
RE https://forum.arctic-sea-ice.net/index.php/topic,327.msg296846.html#msg296846
The change in average CAB drift velocity looks like it could be a major systemic step change. I bet the MOSAIC team wishes they had known what this chart now shows before deciding where to initially park the Polarstern to start their drift year. But does the average value come from enough widely spaced buoys to represent the CAB overall, or is it possible that a few peripheral buoys serve as outliers to have an over-weighted influence thus distorting the CAB average?
The change in average CAB drift velocity looks like it could be a major systemic step change. I bet the MOSAIC team wishes they had known what this chart now shows before deciding where to initially park the Polarstern to start their drift year. But does the average value come from enough widely spaced buoys to represent the CAB overall, or is it possible that a few peripheral buoys serve as outliers to have an over-weighted influence thus distorting the CAB average?
12
Arctic sea ice / Re: The 2020/2021 freezing season
« on: December 29, 2020, 06:01:50 PM »
Nice video A-Team. That view makes me wonder if Nares export could become much more important in the next few years. If open, it provides an exit route for what little remains of MYI.
The Lincoln Sea ice does not look all that solid especially for this time of year. While additional freeze will occur between now and March-April, does the animation provide any hint about how solid the Lincoln Sea ice is likely to be heading into the 2021 melt season relative to recent historical average condition? And does my speculation about the degree of Lincoln Sea "solidity" having an effect on Nares export, and consequently also on the longevity of the heart of the remaining MYI, make any sense? Maybe this belongs in the Stupid questions thread, but also useful to post it just below the animation to see what I'm referring to. (note to others -- you need to double click to see the video in whole-screen mode). The recurring mega-crack north of Greenland seems like it could be another important contributing factor to this scenario.
The Lincoln Sea ice does not look all that solid especially for this time of year. While additional freeze will occur between now and March-April, does the animation provide any hint about how solid the Lincoln Sea ice is likely to be heading into the 2021 melt season relative to recent historical average condition? And does my speculation about the degree of Lincoln Sea "solidity" having an effect on Nares export, and consequently also on the longevity of the heart of the remaining MYI, make any sense? Maybe this belongs in the Stupid questions thread, but also useful to post it just below the animation to see what I'm referring to. (note to others -- you need to double click to see the video in whole-screen mode). The recurring mega-crack north of Greenland seems like it could be another important contributing factor to this scenario.
13
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 23, 2020, 02:36:51 AM »
Here are the relative zero date migrations for each month using Stephan's revised data. The values for Extent and Volume are the number of years earlier the extrapolated date for reaching zero migrated due to changing the period of years used to define the trend from 1979-1998 (= a midyear of ca. 1989) to 1979-2020 (midyear 1999).
By subtracting the amount of change in the projected zero Volume date from the amount of change in the Extent zero date, a Positive value means that the Extent zero date moved earlier by a greater amount, which suggests that Extent losses accelerated to catch up to Volume. A negative difference means the opposite, that the Extent trend estimate changed at a slower rate than the Volume-based estimate.
The original hypothesis was that as ASI declines, eventually the Extent losses will accelerate to catch up to Volume losses, and that Volume is a more reliable predictor for reaching extreme low values such as a BOE (i.e. < 1M km2 Exent and < ca. 0.8M km3 Volume) or the first date with zero ASI. The mechanism for this happening was attributed to accelerated Extent losses as ice thickness gets below a threshold value at which rapid Extent losses can occur. That threshold is incremental, but the effect probably becomes noticeable for a given area of ice when its average thickness gets below about 1 meter. (If I recall correctly, across the Arctic Ocean as a whole, the average thickness during a melt season declines by about 2 meters before ice accumulation and thickness increase begins in late autumn.)
BEGIN THICK ICE MONTHS
Jan: 152 (for Extent) minus 101 (for Volume) = 51 Positive difference. Extent CONverged
The date for zero Extent moved 152 years earlier, while the date for zero Volume moved 101 years earlier. Thus, Extent advanced 51 years more than the Volume date.
Feb: 182 minus 119 = 63 Extent CONverged.
Mar: 20 minus 105 = -85 Extent DIverged, Extent migration was slower than Volume.
Apr: -60 minus 93 = -153 Big DIvergence. (Ext estimate became 63 years LATER).
May: 11 minus 90 = -89 Extent DIverged.
END THICK ICE MONTHS
THICK to THIN TRANSITION
Jun: 72 minus 69 = 3 Slight CONvergence, but essentially Ext and Vol had equal change.
BEGIN THIN ICE MONTHS
Jul: 73 minus 46 = 27 Extent CONverged.
Aug: 120 minus 38 = 82 Extent CONverged.
Sep: 123 minus 45 = 78 Extent CONverged.
Oct: 190 minus 55 = 135 Extent CONverged.
Nov: 157 minus 73 = 80 Extent CONverged.
END THIN ICE MONTHS
THIN to THICK TRANSITION
Dec: 243 minus 98 = 145 Big Extent CONvergence.
The hypothesis that Extent losses during the thin ice months appear to be accelerating to eventually converge with Volume losses seems to hold up.
In the first comparison (using 1979-2008 vs 1979-2020), the Sept difference between the relative change in extrapolated zero date for Extent and Volume was contrary to the hypothesis. In this second comparison (1979-1998 vs 1979-2020) the relative Sept change supports the hypothesis. And this time, the relative changes in Dec, Jan, and Feb Ext vs. Volume zero dates show convergence even though those months were expected (by me at least) to be neutral because the thin ice mechanism expected to drive convergence does not yet exist for those months.
More important than the hypothesis is the larger point is that if we want to estimate when ASI losses will reach some extremely low (never seen in human history) level, then the Volume straight-line trend is a more reliable predictor than the Extent trend. Extrapolating the Volume trend estimates that a first complete or near-complete loss of late-summer ice will occur by 2029-2034. It is interesting and disturbing to see estimates from the straight-line Volume trend getting even earlier as more years are added to the data.
It is too bad we apparently do not still have Tamino available. This is the kind of stuff he would slice and dice and pull whatever meaning exists from the numbers. He might say we are sword fighting with shadows, i.e. the net differences are based on too few years of data to make conclusions. But my guess is that these differences in trend-based estimates would pass statistical muster (my guess being worth exactly nothing, that is why we have statistics - to get past guesswork based on intuitive hunches).
We may have squeezed this lemon dry, but the patterns are interesting. If Stephan or somebody else is up for one more round, it would be interesting to see what comes from comparing non-overlapping periods, i.e. 1979 - 1999 vs 2000 - 2020.
By subtracting the amount of change in the projected zero Volume date from the amount of change in the Extent zero date, a Positive value means that the Extent zero date moved earlier by a greater amount, which suggests that Extent losses accelerated to catch up to Volume. A negative difference means the opposite, that the Extent trend estimate changed at a slower rate than the Volume-based estimate.
The original hypothesis was that as ASI declines, eventually the Extent losses will accelerate to catch up to Volume losses, and that Volume is a more reliable predictor for reaching extreme low values such as a BOE (i.e. < 1M km2 Exent and < ca. 0.8M km3 Volume) or the first date with zero ASI. The mechanism for this happening was attributed to accelerated Extent losses as ice thickness gets below a threshold value at which rapid Extent losses can occur. That threshold is incremental, but the effect probably becomes noticeable for a given area of ice when its average thickness gets below about 1 meter. (If I recall correctly, across the Arctic Ocean as a whole, the average thickness during a melt season declines by about 2 meters before ice accumulation and thickness increase begins in late autumn.)
BEGIN THICK ICE MONTHS
Jan: 152 (for Extent) minus 101 (for Volume) = 51 Positive difference. Extent CONverged
The date for zero Extent moved 152 years earlier, while the date for zero Volume moved 101 years earlier. Thus, Extent advanced 51 years more than the Volume date.
Feb: 182 minus 119 = 63 Extent CONverged.
Mar: 20 minus 105 = -85 Extent DIverged, Extent migration was slower than Volume.
Apr: -60 minus 93 = -153 Big DIvergence. (Ext estimate became 63 years LATER).
May: 11 minus 90 = -89 Extent DIverged.
END THICK ICE MONTHS
THICK to THIN TRANSITION
Jun: 72 minus 69 = 3 Slight CONvergence, but essentially Ext and Vol had equal change.
BEGIN THIN ICE MONTHS
Jul: 73 minus 46 = 27 Extent CONverged.
Aug: 120 minus 38 = 82 Extent CONverged.
Sep: 123 minus 45 = 78 Extent CONverged.
Oct: 190 minus 55 = 135 Extent CONverged.
Nov: 157 minus 73 = 80 Extent CONverged.
END THIN ICE MONTHS
THIN to THICK TRANSITION
Dec: 243 minus 98 = 145 Big Extent CONvergence.
The hypothesis that Extent losses during the thin ice months appear to be accelerating to eventually converge with Volume losses seems to hold up.
In the first comparison (using 1979-2008 vs 1979-2020), the Sept difference between the relative change in extrapolated zero date for Extent and Volume was contrary to the hypothesis. In this second comparison (1979-1998 vs 1979-2020) the relative Sept change supports the hypothesis. And this time, the relative changes in Dec, Jan, and Feb Ext vs. Volume zero dates show convergence even though those months were expected (by me at least) to be neutral because the thin ice mechanism expected to drive convergence does not yet exist for those months.
More important than the hypothesis is the larger point is that if we want to estimate when ASI losses will reach some extremely low (never seen in human history) level, then the Volume straight-line trend is a more reliable predictor than the Extent trend. Extrapolating the Volume trend estimates that a first complete or near-complete loss of late-summer ice will occur by 2029-2034. It is interesting and disturbing to see estimates from the straight-line Volume trend getting even earlier as more years are added to the data.
It is too bad we apparently do not still have Tamino available. This is the kind of stuff he would slice and dice and pull whatever meaning exists from the numbers. He might say we are sword fighting with shadows, i.e. the net differences are based on too few years of data to make conclusions. But my guess is that these differences in trend-based estimates would pass statistical muster (my guess being worth exactly nothing, that is why we have statistics - to get past guesswork based on intuitive hunches).
We may have squeezed this lemon dry, but the patterns are interesting. If Stephan or somebody else is up for one more round, it would be interesting to see what comes from comparing non-overlapping periods, i.e. 1979 - 1999 vs 2000 - 2020.
14
Arctic sea ice / Re: What's new in the Arctic ?
« on: December 22, 2020, 06:54:05 PM »
Killer whales expanding their hunting area by taking advantage of Arcitc sea ice reduction
Even if you aren't interested in the biological story, the scale and stark beauty of the scenery makes it worth watching.
Even if you aren't interested in the biological story, the scale and stark beauty of the scenery makes it worth watching.
15
Arctic sea ice / Re: MOSAiC news
« on: December 19, 2020, 01:50:40 AM »
Dear A-Team. It seems like the Beaufort Gyre is a bit of a sore toe for you, and this thread just stepped on it! I agree that there is a need for precision in scientific terminology and that it is important to not create entities out of spurious patterns. I have similar pet peeves about sloppy terminology in my own field (anytime I read or hear "herbicides and pesticides" a part of my reptilian brain stem is fired causing me to view anything else the author says through a lens of hostile suspicion as being based on polemics and ignorance and probably not worth my precious ever-dwindling time on Earth. 
)
But there is in fact a regular circular pattern of ASI travel, for which the center of rotation is usually located in or near the Beaufort Sea. To discuss this phenomenon, a name is more efficient than calling it "that regular circular pattern of ice travel with a center of rotation usually near the Beaufort Sea." I suppose the acronym "TRCPOITWACORUNTBS" could suffice, but that's too long and reminds me of one of those compound German words for which I pity German school kids having to spell.
Gyre refers to circular motion. And Beaufort refers to the Beaufort Sea. Voila, we have a name: the Beaufort Gyre! As long as people don't over-concretize it as a specific fixed thing instead of a regular but variable pattern, and don't confuse wind-driven ice movement with ocean currents, I don't see the harm. If we want to discuss it we gotta call it something. Later in your post you call this regular pattern "the non-existent Beaufort Ice Gyre". But everybody else seems to agree that it occurs on a regular-enough basis and is of sufficient importance that they need to discuss it in order to understand the system. So how should they refer to that regular pattern?
You include two links.
For the first article by Regan, Lique and Armitage, you credit it for being a "serious treatment". But placing it right after a condemnation of "Publishing garbage diagrams undermines public trust..." is not exactly a rousing endorsement, and feels more like an insult. Given two contrary indicators, I don't know how to interpret your tone. I'm not heavily invested in understanding what Regan et al. call the "BG" (not to be confused Roald Dahl's BFG for Big 'Friendly' Giant, the greatest subversively dirty acronym of all time), but that paper looked pretty good and useful to me.
But what really got me to write was to defend the second link. I found that brief blog post (4 pages including pictures and graphs, so even less to read) by Tom Armitage provides some very useful perspectives on how the Arctic Ocean works as a system and how it interacts with the rest of the planet. If you were upset because Dr. Tom (like the Regan et al. article) commits a cardinal sin in calling lower salinity water "freshwater", I think you'll get better results by politely suggesting that the term should be "fresher" or "lower salinity" water. While I agree with you that water with so much salt in it that it would probably kill you if you tried to survive on it should not be called "freshwater", Regan et al. did at least define "freshwater" as water with salinity below a reference value of 34.8.
Apart from fights about science terminology, I encourage those of you hanging out on ASIF, which means that you must have an interest in the topic, to read the Armitage blog post. It's a quick read and has a high "Oh really, I never knew that or thought of it that way" moments per page ratio. And it has a pretty picture that I was tempted to re-post on the "caa-greenland mega crack" page for the all those crackheads who hang out there.
) But there is in fact a regular circular pattern of ASI travel, for which the center of rotation is usually located in or near the Beaufort Sea. To discuss this phenomenon, a name is more efficient than calling it "that regular circular pattern of ice travel with a center of rotation usually near the Beaufort Sea." I suppose the acronym "TRCPOITWACORUNTBS" could suffice, but that's too long and reminds me of one of those compound German words for which I pity German school kids having to spell.
Gyre refers to circular motion. And Beaufort refers to the Beaufort Sea. Voila, we have a name: the Beaufort Gyre! As long as people don't over-concretize it as a specific fixed thing instead of a regular but variable pattern, and don't confuse wind-driven ice movement with ocean currents, I don't see the harm. If we want to discuss it we gotta call it something. Later in your post you call this regular pattern "the non-existent Beaufort Ice Gyre". But everybody else seems to agree that it occurs on a regular-enough basis and is of sufficient importance that they need to discuss it in order to understand the system. So how should they refer to that regular pattern?
You include two links.
https://sci-hub.se/https://doi.org/10.1029/2018JC014379 rare serious treatment
https://cpom.org.uk/glimpsing-under-the-ice-measuring-the-ice-covered-arctic-ocean-from-space/
For the first article by Regan, Lique and Armitage, you credit it for being a "serious treatment". But placing it right after a condemnation of "Publishing garbage diagrams undermines public trust..." is not exactly a rousing endorsement, and feels more like an insult. Given two contrary indicators, I don't know how to interpret your tone. I'm not heavily invested in understanding what Regan et al. call the "BG" (not to be confused Roald Dahl's BFG for Big 'Friendly' Giant, the greatest subversively dirty acronym of all time), but that paper looked pretty good and useful to me.
But what really got me to write was to defend the second link. I found that brief blog post (4 pages including pictures and graphs, so even less to read) by Tom Armitage provides some very useful perspectives on how the Arctic Ocean works as a system and how it interacts with the rest of the planet. If you were upset because Dr. Tom (like the Regan et al. article) commits a cardinal sin in calling lower salinity water "freshwater", I think you'll get better results by politely suggesting that the term should be "fresher" or "lower salinity" water. While I agree with you that water with so much salt in it that it would probably kill you if you tried to survive on it should not be called "freshwater", Regan et al. did at least define "freshwater" as water with salinity below a reference value of 34.8.
Apart from fights about science terminology, I encourage those of you hanging out on ASIF, which means that you must have an interest in the topic, to read the Armitage blog post. It's a quick read and has a high "Oh really, I never knew that or thought of it that way" moments per page ratio. And it has a pretty picture that I was tempted to re-post on the "caa-greenland mega crack" page for the all those crackheads who hang out there.
16
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 18, 2020, 11:55:37 PM »
To get back to the Convergence question:
The hypothesis is that the number of years remaining until the zero ice date estimated by the Extent trend will decrease relative to the date estimated by Volume as we get closer to that date.
The hypothesis says that until they meet when both Volume and Extent trends reach zero, it is the Extent date that will shift to meet the earlier Volume date, not vice versa.
Here are the relative zero date migrations for 1979-2008 vs. 1979-2020 for each month.
The values for Extent and Volume are the number of years earlier the end date became by adding 2009-2020 to the 1979-2008 dataset.
By subtracting the Volume shift from the Extent shift, a Positive value means that the Extent estimate moved earlier by a greater amount, which is what the hypothesis predicts. A negative difference means the opposite, that instead of drawing closer to the Volume-based estimate, the Extent-based estimate is moving away from it.
Jan: -2 (for Extent) minus 13 (for Volume) = -15
The Vol. estimate got 13 years earlier, but Extent est. became later not earlier, and thus farther away from the Vol estimate. This is the opposite of convergence and NOT what the hypothesis predicts.
Feb: 12 minus 15 = -3
Mar: -22 minus 15 = -37
Apr: -45 minus 15 = -60 (Wow, Ext estimate became 45 years LATER).
May: 6 minus 19 = -19
Jun: 21 minus 20 = 1
Jul: 24 minus 15 = 9
Aug: 20 minus 11 = 9
Sep: 13 minus 14 = -1
Oct: 30 minus 9 = 21
Nov: 27 minus 11 = 18
Dec: 4 minus 10 = -6
As you noted, the winter and spring months are doing the opposite of convergence. While summer and fall are generally showing convergence. That makes sense in that we would expect the "thin ice" months to show convergence between Extent and Volume before the "thick ice" months. It is when thickness reaches a critical low threshold that Extent losses increase causing it to begin to catch up to Volume.
June being a neutral month with respect to the "Extent trend must bend down to catch Volume trend" hypothesis makes sense because it is the transition between the thick ice and the thin ice months.
But September is a brain twister. It seems like it should show a full expression of the 'Extent catches Volume as ice thins' trend. My guess is that those bays in the CAA and other ice traps that are the reason for setting the BOE definition at 1M km2 of residual Extent instead of zero, are already constraining reduction in September Extent. Those areas may be superficial thin ice that add to the Sept. Extent value without adding much to the Sept Volume because they are so thin. As a result, the Sept. Extent value does not decline as much as it "should", but Sept. Volume does not as effectively hide the loss of ice.
It is also a bit mysterious to see the peak "thick ice" months going the opposite direction, i.e. the Extent-trend zero date is getting farther away not closer to the Volume date. And for March and April, the zero Extent estimate is getting absolutely later, not just getting earlier at a slower rate than the Volume date.
My guess is that happens because once the Arctic Ocean fills up with ice, it is full. Even in the colder, higher ice volume past, it could not add more Extent because the Arctic Ocean is surrounded by land. These days, the ice Extent comes from thinner low-volume ice, but that change is not reflected in the Extent value. It still counts for Extent. The March and April constraint on Extent in the past means that as the ice declines now, relative to the previous years, March and April don't show much if any Extent loss. So as more years are added to the dataset, with little change in the constrained monthly Extent values for March and April, the trend towards a Zero Extent date for those months is essentially no trend at all with termination dates over 300 years from now vs. decades for the other months.
Actually, that point applies to ALL of the maximum ice months of January through May. For each of them, the zero Extent year estimate is past 2300, and for Feb-May, in the late 2300s. Thus the negative trend slope is so minor that there really isn't much trend at all due to the constraint on maximum Extent in earlier years.
The "land bound Arctic Sea Ice" argument conveniently ignores the potential for additional Extent in the peripheral seas not bound by the coast of the Arctic Ocean. Are your Extent and Volume data for the entire Arctic, including the peripheral seas, or are they limited to the (mostly land bound) central Arctic Ocean?
If the data are limited to the central Arctic, then I don't have to explain away that potential for additional Extent. But if your data also include those peripheral areas (Greenland, Okhotsk, Bering Seas) that the "land bound Arctic Ocean" argument does not address, I won't even attempt to concoct some reason to explain them away as I have already used up my daily allowance for fabricating "evidence".
The hypothesis is that the number of years remaining until the zero ice date estimated by the Extent trend will decrease relative to the date estimated by Volume as we get closer to that date.
The hypothesis says that until they meet when both Volume and Extent trends reach zero, it is the Extent date that will shift to meet the earlier Volume date, not vice versa.
Here are the relative zero date migrations for 1979-2008 vs. 1979-2020 for each month.
The values for Extent and Volume are the number of years earlier the end date became by adding 2009-2020 to the 1979-2008 dataset.
By subtracting the Volume shift from the Extent shift, a Positive value means that the Extent estimate moved earlier by a greater amount, which is what the hypothesis predicts. A negative difference means the opposite, that instead of drawing closer to the Volume-based estimate, the Extent-based estimate is moving away from it.
Jan: -2 (for Extent) minus 13 (for Volume) = -15
The Vol. estimate got 13 years earlier, but Extent est. became later not earlier, and thus farther away from the Vol estimate. This is the opposite of convergence and NOT what the hypothesis predicts.
Feb: 12 minus 15 = -3
Mar: -22 minus 15 = -37
Apr: -45 minus 15 = -60 (Wow, Ext estimate became 45 years LATER).
May: 6 minus 19 = -19
Jun: 21 minus 20 = 1
Jul: 24 minus 15 = 9
Aug: 20 minus 11 = 9
Sep: 13 minus 14 = -1
Oct: 30 minus 9 = 21
Nov: 27 minus 11 = 18
Dec: 4 minus 10 = -6
As you noted, the winter and spring months are doing the opposite of convergence. While summer and fall are generally showing convergence. That makes sense in that we would expect the "thin ice" months to show convergence between Extent and Volume before the "thick ice" months. It is when thickness reaches a critical low threshold that Extent losses increase causing it to begin to catch up to Volume.
June being a neutral month with respect to the "Extent trend must bend down to catch Volume trend" hypothesis makes sense because it is the transition between the thick ice and the thin ice months.
But September is a brain twister. It seems like it should show a full expression of the 'Extent catches Volume as ice thins' trend. My guess is that those bays in the CAA and other ice traps that are the reason for setting the BOE definition at 1M km2 of residual Extent instead of zero, are already constraining reduction in September Extent. Those areas may be superficial thin ice that add to the Sept. Extent value without adding much to the Sept Volume because they are so thin. As a result, the Sept. Extent value does not decline as much as it "should", but Sept. Volume does not as effectively hide the loss of ice.
It is also a bit mysterious to see the peak "thick ice" months going the opposite direction, i.e. the Extent-trend zero date is getting farther away not closer to the Volume date. And for March and April, the zero Extent estimate is getting absolutely later, not just getting earlier at a slower rate than the Volume date.
My guess is that happens because once the Arctic Ocean fills up with ice, it is full. Even in the colder, higher ice volume past, it could not add more Extent because the Arctic Ocean is surrounded by land. These days, the ice Extent comes from thinner low-volume ice, but that change is not reflected in the Extent value. It still counts for Extent. The March and April constraint on Extent in the past means that as the ice declines now, relative to the previous years, March and April don't show much if any Extent loss. So as more years are added to the dataset, with little change in the constrained monthly Extent values for March and April, the trend towards a Zero Extent date for those months is essentially no trend at all with termination dates over 300 years from now vs. decades for the other months.
Actually, that point applies to ALL of the maximum ice months of January through May. For each of them, the zero Extent year estimate is past 2300, and for Feb-May, in the late 2300s. Thus the negative trend slope is so minor that there really isn't much trend at all due to the constraint on maximum Extent in earlier years.
The "land bound Arctic Sea Ice" argument conveniently ignores the potential for additional Extent in the peripheral seas not bound by the coast of the Arctic Ocean. Are your Extent and Volume data for the entire Arctic, including the peripheral seas, or are they limited to the (mostly land bound) central Arctic Ocean?
If the data are limited to the central Arctic, then I don't have to explain away that potential for additional Extent. But if your data also include those peripheral areas (Greenland, Okhotsk, Bering Seas) that the "land bound Arctic Ocean" argument does not address, I won't even attempt to concoct some reason to explain them away as I have already used up my daily allowance for fabricating "evidence".
17
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 18, 2020, 10:27:43 PM »
Dear Stephan - Nice work and much appreciated. I think that this addition to your monthly trend posts really gets to the heart of the issue.
Everybody else - especially Arctic amateurs like me: Take enough time to understand what these numbers are saying. What may appear at first glance may appear to be an innocuous table of numbers, in truth says major and disturbing things about the future of the Arctic, this planet, humanity in general, and the not-very-distant future for each us individually and the people we love.
1) Lots of talk by IPCC and elsewhere about sea level rise by 2100. No disagreement with that, it is a huge impactful manifestation of our insane management of the planetary life support system. But also consider what it means to have ZERO Arctic sea ice volume in June, the month of maximum solar energy injection, by 2067. Moreover, that the date for that catastrophic milestone gets 20 years earlier when you add 12 years to the straight-line trend to go from 1979-2008 to 1979-2020. Will adding another 12 years, i.e. 1979-2032 put that date at 2047?
A planet without its reflective polar cap in June is a different planet than the one we were born on.
2) If 2047-2067 is too far off to get your interest, how about 2032-2035? And what about 2026? Is that close enough to get your attention as being real?
ZERO Arctic Sea in August - October is also a radically different planet. While far below June, there is still considerable solar energy input in August. And an ice-free Arctic Ocean in October (and with much reduced ice in November) venting heat into the atmosphere is bound to have strong effects on mid-latitude weather patterns.
The table highlights the fact that adding 12 years to the dataset used to define the trend pushes the zero volume dates 9-14 years earlier. 2032-2035 is already close at hand, but will those trend endpoints continue to get earlier as each new year is added? Where will those endpoint dates be in just 6 more years in December 2026? The "trend of the trends" suggests that the estimated ice-free Sept date by then could be another six years earlier, i.e. 2026. At risk of piling extrapolations on top of each other, does that suggest that we could already have had a zero-ice September by then?
One of the problems in conceptualizing climate change is that the perceived impacts are in the future. People already dealing with wildfires, heat waves, droughts, hurricanes, crop failures etc. will have a more immediate perspective, but for many/most of us, the climate changes that worry us are said to be decades ahead and so bring a bit less visceral fear.
The dates shown for zero ice volume are nothing new to me, so I've long had the mental concern. And perhaps I am misinterpreting and over-reacting to seeing the earlier progression of endpoint dates that result from adding 12 years to the dataset. But my visceral fear just went up. My emotional operating principle has been that the proverbial poop could hit the fan if global average surface temperature reaches +1.5C over preindustrial circa 2030.
I keep thinking that my understanding of climate change and Arctic Sea Ice decline has reached a level of stability at which I can at least see the horror for what it is, and at least define the problem. But the damn problem keeps growing like a cancerous tumor. Seeing that date migration of the Sept. zero ice year has me wondering if I should recalibrate my gut-level fear threshold and "poop in the fan" date more towards August 2026 - less than 68 months from now.
Of course, ranting aside, the "Now" is all that we can change to affect the Future. I hope your data serves as that one additional piece of alarming evidence that tips the scales to wake up the political and business powers to realize that the money won't do any good if there is not a livable planet on which to spend it. Sorry for such a bleak message as we head into the traditional western holiday season. I would highlight the fact that some good things are also underway, but this message is already long. So yes, there are also some good possibilities emerging. We MUST make those possibilities real.
Everybody else - especially Arctic amateurs like me: Take enough time to understand what these numbers are saying. What may appear at first glance may appear to be an innocuous table of numbers, in truth says major and disturbing things about the future of the Arctic, this planet, humanity in general, and the not-very-distant future for each us individually and the people we love.
1) Lots of talk by IPCC and elsewhere about sea level rise by 2100. No disagreement with that, it is a huge impactful manifestation of our insane management of the planetary life support system. But also consider what it means to have ZERO Arctic sea ice volume in June, the month of maximum solar energy injection, by 2067. Moreover, that the date for that catastrophic milestone gets 20 years earlier when you add 12 years to the straight-line trend to go from 1979-2008 to 1979-2020. Will adding another 12 years, i.e. 1979-2032 put that date at 2047?
A planet without its reflective polar cap in June is a different planet than the one we were born on.
2) If 2047-2067 is too far off to get your interest, how about 2032-2035? And what about 2026? Is that close enough to get your attention as being real?
ZERO Arctic Sea in August - October is also a radically different planet. While far below June, there is still considerable solar energy input in August. And an ice-free Arctic Ocean in October (and with much reduced ice in November) venting heat into the atmosphere is bound to have strong effects on mid-latitude weather patterns.
The table highlights the fact that adding 12 years to the dataset used to define the trend pushes the zero volume dates 9-14 years earlier. 2032-2035 is already close at hand, but will those trend endpoints continue to get earlier as each new year is added? Where will those endpoint dates be in just 6 more years in December 2026? The "trend of the trends" suggests that the estimated ice-free Sept date by then could be another six years earlier, i.e. 2026. At risk of piling extrapolations on top of each other, does that suggest that we could already have had a zero-ice September by then?
One of the problems in conceptualizing climate change is that the perceived impacts are in the future. People already dealing with wildfires, heat waves, droughts, hurricanes, crop failures etc. will have a more immediate perspective, but for many/most of us, the climate changes that worry us are said to be decades ahead and so bring a bit less visceral fear.
The dates shown for zero ice volume are nothing new to me, so I've long had the mental concern. And perhaps I am misinterpreting and over-reacting to seeing the earlier progression of endpoint dates that result from adding 12 years to the dataset. But my visceral fear just went up. My emotional operating principle has been that the proverbial poop could hit the fan if global average surface temperature reaches +1.5C over preindustrial circa 2030.
I keep thinking that my understanding of climate change and Arctic Sea Ice decline has reached a level of stability at which I can at least see the horror for what it is, and at least define the problem. But the damn problem keeps growing like a cancerous tumor. Seeing that date migration of the Sept. zero ice year has me wondering if I should recalibrate my gut-level fear threshold and "poop in the fan" date more towards August 2026 - less than 68 months from now.
Of course, ranting aside, the "Now" is all that we can change to affect the Future. I hope your data serves as that one additional piece of alarming evidence that tips the scales to wake up the political and business powers to realize that the money won't do any good if there is not a livable planet on which to spend it. Sorry for such a bleak message as we head into the traditional western holiday season. I would highlight the fact that some good things are also underway, but this message is already long. So yes, there are also some good possibilities emerging. We MUST make those possibilities real.
18
Arctic sea ice / Re: MOSAiC news
« on: December 17, 2020, 05:16:43 PM »<snip>
Not a single buoy (or multi-buoy succession) over the last 40 years has ever completed the oft-pictured full gyre (per uniq's ongoing displays).
I'm glad you pointed that out. Watching those buoy drifts I figured that my confusion at not seeing a big sweep around the famed Beaufort Gyre as expected was yet another manifestation of my ignorance about Arctic complexities. If there had only been buoy tracks from the last few years I might have assumed that tracks from the 1980s would have displayed the expected majestic journeys around the Arctic. In which case I might have cried out to the heavens that the sky is falling because the recent buoy tracks indicate that the epic Beaufort Gyre has collapsed! But those buoy tracks from the early 1980s don't show much gyre action either, while they do show Fram export.
Is the Beaufort Gyre more hype than reality? Or do the buoy tracks not accurately represent the full degree of drift at the temporal and spatial scales in the animations? Or am I completely missing the point about what the buoy track animations do, don't, and should show?
19
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 16, 2020, 11:13:44 PM »
Thanks for the reply Stephan. If/when I get around to addressing what is really just a statistical fetish, it would not be difficult to get the extrapolated BOE dates from regressions of annual values for Ext, Vol, and Thickness for incrementally later sets of years
(e.g. calculate the Ext and Vol/Thickness trends with data for 1978 - 1988, then 1980 - 1990, 82-92, etc., then for each set of years record the difference between estimated BOE year based on Extent trend minus estimated year based on Vol/Thickness trend).
The point of this obsessive number crunching would be to see if the difference between the Extent-based vs. Volume-based BOE estimate is already getting smaller through time, aka the
'Great Convergence". But since I don't really expect the convergence to emerge until closer to the endpoint, I won't be convinced that my theory is incorrect even if that difference is not yet diminishing. Which is troubling because it means that in a way I am as situationally immune to math as certain psychiatrically-damaged morally-void politicians who shall remain nameless in order to keep this forum apolitical.
(e.g. calculate the Ext and Vol/Thickness trends with data for 1978 - 1988, then 1980 - 1990, 82-92, etc., then for each set of years record the difference between estimated BOE year based on Extent trend minus estimated year based on Vol/Thickness trend).
The point of this obsessive number crunching would be to see if the difference between the Extent-based vs. Volume-based BOE estimate is already getting smaller through time, aka the
'Great Convergence". But since I don't really expect the convergence to emerge until closer to the endpoint, I won't be convinced that my theory is incorrect even if that difference is not yet diminishing. Which is troubling because it means that in a way I am as situationally immune to math as certain psychiatrically-damaged morally-void politicians who shall remain nameless in order to keep this forum apolitical.
20
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 16, 2020, 05:49:57 PM »
Thanks for tracking the data Stephan.
I don't expect the "Great Convergence" between Extent and Volume trends until closer to the endpoint as Volume gets below about 0.8 km3 and when the average thickness is below 0.8 meter. But you mentioned that the Ext and Vol trends are already converging.
Do you have a record over recent years of the difference between the extrapolated zero-year estimates for Extent and Volume trends? That would be interesting to see, and would correct the mistaken (IMHO) assumption by some who think the Extent trend is an accurate predictor for the first, and then regular, BOE status in Septembers.
My view is that Vol. dictates Ext., not vice versa. And that as Thickness declines there will be an acceleration of Extent decline until it catches up to Volume at zero. Thus, first <1m km2 Extent BOE around 2030 or earlier, not around 2060 as estimated from extrapolation of the Extent trend. Multiple other correlated indicators such as global average surface temperature and cumulative atmospheric CO2 ppm also point to BOE status being reached around the same time as the Volume trend estimate.
The problem with Extent, as noted in JC Garcia's tagline, is that Extent alone hides about half of the ice losses because it does not account for simultaneous Thickness reduction.
I don't expect the "Great Convergence" between Extent and Volume trends until closer to the endpoint as Volume gets below about 0.8 km3 and when the average thickness is below 0.8 meter. But you mentioned that the Ext and Vol trends are already converging.
Do you have a record over recent years of the difference between the extrapolated zero-year estimates for Extent and Volume trends? That would be interesting to see, and would correct the mistaken (IMHO) assumption by some who think the Extent trend is an accurate predictor for the first, and then regular, BOE status in Septembers.
My view is that Vol. dictates Ext., not vice versa. And that as Thickness declines there will be an acceleration of Extent decline until it catches up to Volume at zero. Thus, first <1m km2 Extent BOE around 2030 or earlier, not around 2060 as estimated from extrapolation of the Extent trend. Multiple other correlated indicators such as global average surface temperature and cumulative atmospheric CO2 ppm also point to BOE status being reached around the same time as the Volume trend estimate.
The problem with Extent, as noted in JC Garcia's tagline, is that Extent alone hides about half of the ice losses because it does not account for simultaneous Thickness reduction.
21
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: December 16, 2020, 05:21:38 PM »
Hansen posted a short Q&A to reply to questions he got from yesterday's post about acceleration. Not trying to turn ASIF into a climate blog, but it's all connected and it's Hansen talking, not Joe down at the local bar. Q&A is at http://www.columbia.edu/~jeh1/mailings/2020/20201216_Twittering.pdf
22
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: December 14, 2020, 11:35:06 PM »
RE: 2020 global average surface temperature.
Hansen speaks. All should listen. Excerpt below. Full message at http://www.columbia.edu/~jeh1/mailings/2020/20201214_GlobalWarmingAcceleration.pdf
Hansen speaks. All should listen. Excerpt below. Full message at http://www.columbia.edu/~jeh1/mailings/2020/20201214_GlobalWarmingAcceleration.pdf
23
Arctic sea ice / Re: The caa-greenland mega crack
« on: December 14, 2020, 01:25:10 AM »
Thanks to A-team and uniquorn for the heavy lifting on neXtSIM.
The amount of change in just one hour in the two frames of the top image are hard to believe as being anything close to realistic. The ice could not possibly have changed that much in one hour. Are the date and time stamps correct? Or does the methodology allow for large variation between images taken just one hour apart?
Not complaining, just trying to understand. Even if neXtSIM images exaggerate variation, that is OK as long as the exaggeration is consistent and therefore can be accounted for in interpretation. But if inconsistent, such as big differences in how the method distorts data for images just one hour apart, then interpretation becomes almost impossible because you won't know what degree of exaggeration to account for. I'm rooting for neXtSIM as being a superbly informative monitoring tool if it comes with a stable frame of reference for how to interpret images. Otherwise it would just be pictures that can mean different things at different days or hours, i.e. just images without much meaning.
The amount of change in just one hour in the two frames of the top image are hard to believe as being anything close to realistic. The ice could not possibly have changed that much in one hour. Are the date and time stamps correct? Or does the methodology allow for large variation between images taken just one hour apart?
Not complaining, just trying to understand. Even if neXtSIM images exaggerate variation, that is OK as long as the exaggeration is consistent and therefore can be accounted for in interpretation. But if inconsistent, such as big differences in how the method distorts data for images just one hour apart, then interpretation becomes almost impossible because you won't know what degree of exaggeration to account for. I'm rooting for neXtSIM as being a superbly informative monitoring tool if it comes with a stable frame of reference for how to interpret images. Otherwise it would just be pictures that can mean different things at different days or hours, i.e. just images without much meaning.
24
Arctic sea ice / Re: MOSAiC news
« on: December 10, 2020, 02:23:52 AM »
Are the neXtSIM animations going to be available near real-time to track the 2021 melt season? Even if the view is biased above absolute values, as long as the bias is consistent those animations would provide a useful view of melt season progress.
25
Arctic sea ice / Re: What's new in the Arctic ?
« on: December 09, 2020, 12:22:08 AM »
2020 Arctic Report Card summary --
The Arctic is getting hotter, greener and less icy much faster than expected, report finds
https://www.cnn.com/2020/12/08/weather/noaa-arctic-report-card-2020-climate-change/index.html
Inside Climate News version
https://insideclimatenews.org/news/08122020/annual-report-card-marks-another-disastrous-year-for-the-arctic/
Edit - The Arctic Report Card 2020 is online, with a summary at
https://www.arctic.noaa.gov/Report-Card/Report-Card-2020
The Arctic is getting hotter, greener and less icy much faster than expected, report finds
https://www.cnn.com/2020/12/08/weather/noaa-arctic-report-card-2020-climate-change/index.html
Inside Climate News version
https://insideclimatenews.org/news/08122020/annual-report-card-marks-another-disastrous-year-for-the-arctic/
Edit - The Arctic Report Card 2020 is online, with a summary at
https://www.arctic.noaa.gov/Report-Card/Report-Card-2020
26
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: December 02, 2020, 04:48:42 PM »
Correction to previous post - the comparison was to the most recent 30-year average, not "ca. 100 years in the historical record". But your point still applies. You would not lose much money by always betting on the warmer tercile.
27
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 02, 2020, 01:50:18 AM »
FWIW - don't bother with the first two videos (esp. #2 which is mostly self-promotion of his web/Facebook stuff). You won't miss anything by skipping #1 and #2, because the same points get repeated and then repeated again when he actually gets to reading the journal article to you in video 3.
If it sounds like I'm ragging on Beckwith, I am. I lost confidence in him a few years ago when he made what other sources indicated was an incorrect alarming claim about jet stream activity. (I don't know enough to judge, just comparing sources). I do appreciate Tom for posting this and Beckwith for bringing attention to what appears to be an important, though not necessarily as definitive as implied, study and conclusions. To their credit, the authors say "It should be noted that this application of EOF analysis reveals statistical relationships only, and future research will require targeted modeling experiments to verify causal mechanisms." Whereas, Beckwith makes it sound like he has found the missing link that explains all. (And BTW, Jennifer Francis rocks!) You can read the article to yourself via open access at https://iopscience.iop.org/article/10.1088/1748-9326/abc047/pdf
Maybe I should just appreciate anybody that brings attention to the climate crisis, but IMHO Beckwith is not the most accurate or reliable source and his commercializing the catastrophe is offputting.
If it sounds like I'm ragging on Beckwith, I am. I lost confidence in him a few years ago when he made what other sources indicated was an incorrect alarming claim about jet stream activity. (I don't know enough to judge, just comparing sources). I do appreciate Tom for posting this and Beckwith for bringing attention to what appears to be an important, though not necessarily as definitive as implied, study and conclusions. To their credit, the authors say "It should be noted that this application of EOF analysis reveals statistical relationships only, and future research will require targeted modeling experiments to verify causal mechanisms." Whereas, Beckwith makes it sound like he has found the missing link that explains all. (And BTW, Jennifer Francis rocks!) You can read the article to yourself via open access at https://iopscience.iop.org/article/10.1088/1748-9326/abc047/pdf
Maybe I should just appreciate anybody that brings attention to the climate crisis, but IMHO Beckwith is not the most accurate or reliable source and his commercializing the catastrophe is offputting.
28
Arctic sea ice / Re: MOSAiC news
« on: December 01, 2020, 11:06:14 PM »<snip>
"It's not completely clear what the 'floes' and 'leads' actually represent down on the ice as these features are below the resolution of any of the satellite tools used by nextSim. Whatever, they do seem to allow an accurate depiction of ice movement, notably the pick-up in Fram export in mid-November."
and <snip>
"The anisotropic nature of sea ice deformation is made evident by the analysis of satellite-imagery derived ice motion products which shows that high strain rates concentrate along oriented, linear-like faults, or leads, often termed “linear kinematic features” (Kwok, 2001). The signature of the strong heterogeneity and intermittency of sea ice deformation is the emergence of spatial and temporal scalings in the deformation fields over a wide range of scales."
Nice work A-Team. The fracturing of the ice pack depicted in the B&W mp4 is stunning. How close to reality is that imagery, or are the dark lines and pockets exaggerated by model processing of the input data?
The Sept 19, 2020 image is bad enough, but the Oct 3 image is even more striking. While there is some consolidation just north of the CAA and Greenland between Sept. and Oct., a large section of the Atlantic - western Siberian front (accounting for ~10-20% of the total remaining ice, and extending almost to the North Pole) in October looks even more broken up and disbursed than in September, and even closer to being obliterated. That makes me wonder if there had been one more push over the edge, 2020 would have quickly been at or below the 2012 record low minimum Extent, Area and Volume.
Either way, that imagery highlights the frailty of the ASI condition in Sept. and Oct. more dramatically than the numerical charts and even the charts showing loss of MYI.
29
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: December 01, 2020, 10:27:43 PM »I am not sure these seasonal forecasts are good for anything....If you are right about that, that's an awful lot of highly skilled time...wasted...
A couple of years ago I did some home-brew testing of the skill of short-term and "seasonal" (=3 month groupings) forecasts for temperature and precipitation. The criterion was how much improvement the forecasts/outlooks provided compared to a simple climatology estimate as to whether the period would be in the upper, middle, or lower third relative to <edit> the 30 year historical average
Results are shown in charts below. Note that the testing is done on NOAA forecasts and outlooks for the Northeastern United States, not the Arctic. Also note that the scales on the two charts are different.
The first chart shows that at the 1-month range, forecast skill is down to around 10% improvement over climatology. The skill decay shown on the chart is relative to the very high skill for the short-range forecasts. So it is a glass half-full vs. half-empty situation. Short-range temperature forecasting is really good, so it is not surprising that longer-range outlooks have less skill.
I was surprised that the 1-3 and 2-4 month temperature outlooks were better than the 1-month outlooks. That may be a fluke, but it may be because they benefit from estimating temperature over a longer, and therefore less specific, time period.
If we consider 10% improvement over climatology as a threshold for useful improvement, then the first chart shows that temperature outlooks, with skill improvement of ca. 15-20% out to at least 2-to-4 months, have some long-range skill for the northeastern U.S. Conversely, precipitation forecasts run out of skill between 14 days and 1-month. That lines up with some studies I've seen that found long-range precip forecasting losing skill at about 3 weeks. But that's just me waving my arms about stuff I don't keep up with or in detail, so buyer beware.
The second chart (using a more compressed vertical axis scale) shows that within the multi-month outlooks, the temperature outlooks stayed above 10% improvement out to the 4-to-6 month range, whereas precipitation skill bumps around the floor of statistical noise at every range from 1-to-3 months and beyond, thus again indicating a lack of long-range precipitation forecast skill (but they at least avoided negative scores which were possible).
That uptick at 7-9 months for temperature forecasts is intriguing. It could just be statistical noise. But it could also reflect ENSO (El Nino/La Nina) forecasts actually having some slight (remember, we are talking about a mere 10% improvement over random guessing) skill at nudging the prediction in the right direction.
A few years ago at a climate modeling workshop in Florida I met lots of folks from the southeast U.S. and got a different view of things vs. my home turf where there seems to be little attention given to local impact of ENSO forecasts. But those southeastern U.S. folks absolutely worship the ENSO forecasts. With good reason, as there is much higher correlation for their region with regard to the ENSO effects on temperature, and especially precipitation, in the following months. That highlights the fact that my informal (not subjected to statistical significance) testing for the northeastern U.S. does not necessarily apply to even other U.S. regions, much less the entire planet.
30
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: November 23, 2020, 10:17:10 AM »What's more, my observation is that the more open the Chukchi and the more iced over the Hudson, the warmer it is in Europe during winter. So here I plot Hudson % ice cover minus Chukchi %icecover on Dec 1, and European winter temp anomaly. Lo and behold
Quotes below are from
"Warm Arctic, Cold Continents? It Sounds Counterintuitive, but Research Suggests it’s a Thing"
https://insideclimatenews.org/news/20112020/warm-arctic-cold-continents-climate-change
"Low sea ice in the Chukchi Sea, north of Alaska, seems to match up with severe winter conditions in Eastern North America, and low sea ice in the Barents and Kara Seas, north of Siberia, match with cold winters over Asia."
But there is disagreement about the strength of the effect, with Jennifer Francis and James Screen expressing different views.
And this from Judah Cohen:
""I'm not arguing that winters are getting colder, I'm saying winters are colder than the models predict, and I think that will continue," he said. "The models are constantly being updated, every winter and the divergence between their projections and the observations is striking." By contrast, he added, the model predictions for summers are nearly perfect."
31
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 21, 2020, 01:42:57 AM »
Then I look at Polyakov et al. 2020 and start to wonder if all this attention to top-side forcings overlooks the near-surface turbulence with vertical mixing and below-surface halocline/thermocline & heat diffusion transformation that could be where the major forcing is taking place. It's too bad we don't have equivalent graphical products for tracking and prediction of "ocean weather" (e.g. water temperature, salinity plumes, movement of water masses analogous to air masses, etc.). Those measures are available, but their presentation is not as highly developed or as routinely presented for layperson consumption as the atmospheric weather products we are used to.
My growing suspicion is that like a drunk looking for his keys under the street light, we are focusing our attention where it is easiest to see what's going on. But to understand the real situation we need to look at a broader range of monitoring tools. It is often said that the Arctic provides never-ending surprises. Perhaps our above-surface bias is a contributing factor to our being regularly surprised (says the guy who just posted 4 air temperature charts).
A-Team, uniquorn and others are posting stuff about the water world perspective. Much of it is not as easy to summarize for the lay reader (like me) to intuitively understand. A chart showing a big red blob marking a positive aerial temperature anomaly over the Arctic is easy to understand. Similar synoptic standardized graphs for the surface and sub-surface water measures would be a useful addition. Easy for me to say because I'm not going to be the one to do anything about it.
I'm just pointing out that 71% of the Earth's surface that interacts with greenhouse gas heat-trapping insulation is water. That 93% of the added heat energy from global warming is in the water. That H2O vapor is a stronger greenhouse gas than CO2. And now, with respect to the ASI, Polyakov and others are quantifying what should have been obvious all along (and probably was to those who study this stuff) that those of us watching the ASI drama need to pay more attention to the water that the ice is floating in and made from if we want to understand what is going on.
My growing suspicion is that like a drunk looking for his keys under the street light, we are focusing our attention where it is easiest to see what's going on. But to understand the real situation we need to look at a broader range of monitoring tools. It is often said that the Arctic provides never-ending surprises. Perhaps our above-surface bias is a contributing factor to our being regularly surprised (says the guy who just posted 4 air temperature charts).
A-Team, uniquorn and others are posting stuff about the water world perspective. Much of it is not as easy to summarize for the lay reader (like me) to intuitively understand. A chart showing a big red blob marking a positive aerial temperature anomaly over the Arctic is easy to understand. Similar synoptic standardized graphs for the surface and sub-surface water measures would be a useful addition. Easy for me to say because I'm not going to be the one to do anything about it.
I'm just pointing out that 71% of the Earth's surface that interacts with greenhouse gas heat-trapping insulation is water. That 93% of the added heat energy from global warming is in the water. That H2O vapor is a stronger greenhouse gas than CO2. And now, with respect to the ASI, Polyakov and others are quantifying what should have been obvious all along (and probably was to those who study this stuff) that those of us watching the ASI drama need to pay more attention to the water that the ice is floating in and made from if we want to understand what is going on.
32
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 20, 2020, 10:08:34 PM »I still find 2018 the best analogue. We are cca 2 weeks behind:
1. That is a great comparison. Does anybody have an estimate for how much thickness addition is lost for the April maximum by a two week delay in November freezing?
---------------------------------
2. Late-September to mid-November 2020 DMI 80+N temperatures (first chart) continue to track almost as high as same dates in 2016 (second chart), and similar to but slightly warmer (eyeball estimate) than same dates in 2018 (third chart).
Will 2020 continue as warm until the end of the year as 2016, or follow the cooler (but still warmer than most years) track of late 2018?
The fourth chart of GFS 2M temperature anomaly forecast on Climate Reanalyzer suggests that 2020 high Arctic temperatures will continue well above the climatic average for the next 10 days.
Despite the completely expected period of accelerated Extent and Area gains after the delayed start, late 2020 so far is not providing much indication for a robust compensatory refreeze after the low September minimums. Refreeze season is just barely over 50% done, so too early to estimate, but from what we have seen so far it is looking like ASI could enter the 2021 melt season in an unusually vulnerable condition from the surface-and-above view.
33
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 17, 2020, 03:42:35 PM »
More Tamino goodness (referring to annual average ASI Extent):
"....annual average sea ice extent is not only still well below what it was 30 years ago, it’s well below what it would have been had the downward trend at that time continued unabated:"
Bolding added. See graph below. And remember that adding 2016-2020 to the data in the Tamino graph keeps the linear trend heading downward.
As for the Extent line requiring >40 years to go below 1M km2, look at the Volume graph. It reaches 0 in mid 2032. No Volume means no Extent. (Digression - for some reason I'm reminded of Firesign Theatre's Porgy and Mudhead going to MoreScience High School the day before graduation, only to find that the Communists have stolen it!).
As for which curve rules, remember that as average Thickness gets below 1M the ice is less resistant to melt. Volume dictates Extent, not the other way around
Tamino slammed the door shut on any notion of slowdown. Arguing about the details really misses the point I think we all agree upon - the Arctic Sea Ice is getting destroyed. The first BOE is just a day that will come and go. The more pertinent questions are -
1) What can we do to slow the process? (I'll defer any mention of reversal until we do the first step of slowing the acceleration).
Of course, we already know. Slow, then stop, then reverse greenhouse gas emissions. The one good thing about loss of ASI is that it provides easily relatable visual demonstration of the progression and effects of climate change.
2) What does diminishing ASI mean for weather patterns and other ecosystem changes that will affect all of us far beyond the Arctic?
"....annual average sea ice extent is not only still well below what it was 30 years ago, it’s well below what it would have been had the downward trend at that time continued unabated:"
Bolding added. See graph below. And remember that adding 2016-2020 to the data in the Tamino graph keeps the linear trend heading downward.
As for the Extent line requiring >40 years to go below 1M km2, look at the Volume graph. It reaches 0 in mid 2032. No Volume means no Extent. (Digression - for some reason I'm reminded of Firesign Theatre's Porgy and Mudhead going to MoreScience High School the day before graduation, only to find that the Communists have stolen it!).
As for which curve rules, remember that as average Thickness gets below 1M the ice is less resistant to melt. Volume dictates Extent, not the other way around
Tamino slammed the door shut on any notion of slowdown. Arguing about the details really misses the point I think we all agree upon - the Arctic Sea Ice is getting destroyed. The first BOE is just a day that will come and go. The more pertinent questions are -
1) What can we do to slow the process? (I'll defer any mention of reversal until we do the first step of slowing the acceleration).
Of course, we already know. Slow, then stop, then reverse greenhouse gas emissions. The one good thing about loss of ASI is that it provides easily relatable visual demonstration of the progression and effects of climate change.
2) What does diminishing ASI mean for weather patterns and other ecosystem changes that will affect all of us far beyond the Arctic?
34
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 17, 2020, 03:29:46 AM »
NSIDC Extent minima, including 2016-2020 that Tamino did not have available for his analysis through 2015, showing that adding 2016-2020 continues the long term linear downward trend.
35
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 17, 2020, 02:44:17 AM »RE": <snip> The trend in the sea ice decline has slowed considerably over the past 15 years, compared to the previous 15. Every year, the possibility of a BOE increases. However, the recent trend shows that it is highly unlikely prior to 2030.
Tamino/Grant Foster is/was the king of change point analysis.
And he did an analysis in 2015, based on extent anomaly data. For sea ice minimum, he found one change point, in 1996 if I read the graph correctly.
https://tamino.wordpress.com/2015/10/01/arctic-sea-ice-2/
I do not see the slowdown in the two Volume graphs shown below. It looks like a consistent ongoing trend to me. All the data points since 2005 are well within the expected variability of the downward linear trend. The Volume minima for all of the last 6 years, and 7 out of the last 8, are within one standard deviation (=close) to the trend line.
As for annual average Extent, the great Tamino did not find a slowdown when looking at data through 2015. He did find a temporary slowing for 2002-2006, then for 2006-2015 it was back to the original downward rate of decline. See whisker graphs in the 3rd graph below.
When Tamino looked at annual Extent minima, he found a statistically significant increase in the rate of decline in 1996 (see the downward kink in the blue line of the 4th graph below). He did comment that a smoothing of the data hinted at a possible plateauing in the final few years of those data, but there was too much variability to conclude anything about a rate change based on so few points in such variable data. The Extent minima in the subsequent years (2016-2020) proved that his caution about concluding anything about the long term trend from those few years was justified. When 2016-2020 are added, the trend resumes its linear downward slide, thus refuting that hint of a rate plateau (to my eyes, not statistically tested, but I'd bet my lunch money on how that test would come out). See the NSIDC graph in the next post. I wish we still had Tamino or someone with his skill set putting such questions through the statistical blender.
While it is possible that "negative" suppressive feedbacks to slow further losses will strengthen and dominate as Volume gets closer to zero, it seems more likely that the reverse is more likely, i.e. that "positive" reinforcing feedbacks are more likely to strengthen and dominate to accelerate losses.
Most ASIF folks already know the list of potential reinforcing feedbacks, so I won't repeat them. The weakening of halocline stratification is a more recently recognized (to me at least) addition to that list. Based on studies by Polyakov et al., Timmermans et al., and others, the surface - subsurface water characteristics and relations seem to be of increasing importance for at least some locations in the Arctic Ocean, though I have not read those studies closely or recently enough to comment on the scale of their potential impact relative to entire regional seas or to the Arctic Ocean overall.
My question about unexpected drift pattern may be unjustified alarmist arm-waving, but with people in the Forum more familiar with the historical record it seems worth asking to either confirm my suspicion or dismiss it. (The only "dumb" question is the one left unspoken.)
Even if the November 2020 drift graph posted by A-Team is just a meaningless blip, that still leaves the weightier statement about decline of halocline stratification in the Polyakov et al. abstract (and by my inference, the consequent decline in isolation of ASI from interaction with subsurface water). Seeing an expert like Polyakov use the term "tipping point" about any aspect of the ASI is enough to give me the willies.
I do admit that my ears are tuned to hear that dog whistle, because I fully expect that by pushing the climate system, and the Arctic in particular, beyond its previous "performance envelope", then something is going to snap in a non-linear, non-incremental, and very abrupt and "surprising" (but we knew it was coming in one form or another) way.
36
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 16, 2020, 11:20:09 PM »<snip>As sea ice declines, a new Arctic state is emerging which due to the positive feedback mechanism outlined above may be pushing the system toward a tipping point."
1. Uh oh. "Weakening halocline stratification" and "Tipping point" in the same abstract sounds ominous. The decay trends we've been watching, while rapid relative to most natural transitions, are slow and incremental compared to what a halocline tipping point could bring.
I may be incorrect in viewing halocline and thermocline as directly related, but my guess is that is how the summer ASI will get obliterated. Not by a gradual continuation of the forcings and trends monitored and analyzed so far, but by transition to a new functional system state where multiple factors work in concert to melt sea ice at a MUCH faster rate and by different mechanisms than the processes monitored in recent years.
2. Different topic: I know that the Arctic drift pattern can change greatly between short time periods, but the counterclockwise pattern in the drift pattern in A-Team's Nov. 16 MOSAIC post seems unusually strong and in the wrong direction.
Is this another indication/consequence that the Beaufort Gyre no longer exists or has been transformed into a new pattern? Or am I overinterpreting a short term condition?
3. Vertical disruption (i.e. halocline stratification reduction)
x Horizontal disruption (odd drift pattern)
= an altered Arctic.
IMHO none of this bodes well for ASI. BOE by or before 2030 seems not only increasingly possible, but inevitable.
37
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 12, 2020, 03:15:13 PM »
Thanks Oyvind. That post belongs in the Tamino Hall of Fame collection. I miss that guy. His site is still up but nothing new for months.
38
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 12, 2020, 06:40:41 AM »
Tamino/Grant Foster is/was the king of change point analysis. Grant, if you're listening we need you back! Until he or someone else shows up, I can only relate that from many Tamino blog posts that used change point, one theme was that what looks like a valid change point is not when subjected to statistical testing. Non-random significance (like beauty) is often in the eye of the beholder. I'm not saying this to rain on the "2007 fundamental change" question, I am just noting that until we have a statistical test the eyeball view alone cannot be trusted.
FWIW, my own opinion about 2007 is to agree with you from a different basis. It seems to me that the loss of multi-year ice in 2007 either reflected or helped initiate systemic changes in the ASI system. Various posts in the forum have described how, even though 2012 gets most of the attention since it holds the records, that when looked at from different points of view, 2007 was the Big Year. I have no hope of remembering in which thread, but (I think it was) Oren or BFTV who put up a post this summer listing losses from September to September which showed that when viewed from that time frame, 2007 outdistanced every other year for losses. So that's a second (but also not statistically validated) observation to lend weight to your proposition.
2012 had strong summer melt season weather topped off by perfectly timed and positioned cyclone to break up ice and pull subsurface heat to cause new low September minima. I don't have 2007 summer melt weather in my head, but I don't think it was as forceful as 2012, and certainly did not have a storm like the GAC 2012 to push it over the edge. Which leaves it up to other underlying changes that caused (at the time) new record lows.
My foggy recollection is that one contributing factor in 2007 was just enough extra floe mobility combined with conditions conducive for Farm or CAA export to send a lot of multi-year ice out of the central Arctic Ocean to its southern doom. I also think that the Beaufort Gyre faltered as the nursery for multi-year ice in 2007. Perhaps folks with a better handle on these fuzzy factoids can bolster or refute them, or add other lines of evidence about whether 2007 brought unique forces or outcomes to the ASI saga. After the unprecedented losses in 2007, there were journal article autopsies about what caused the losses observed that year. I don't have any specific links to share, but they exist.
As for photobucket. It sounds like you have Excel. You can make charts in Excel, save them as screen clips to Excel or Word, then click on the image and "Save as Image" to make a file copy on your hard drive. With that done, then when you write an ASIF post, use the Attachment link below the text box on the Reply screen to upload those saved chart images.
Sorry if that it is so blindingly obvious that you are wondering why I would bother to mention it. Here is why. I was messing around with different image hosting services until somebody on ASIF reminded me about the Attachment link on the Reply post form. I had not realized that was a way to upload images. Yet another in a lifetime of dope-slap to forehead moments, i.e. making something difficult that did not have to be. The Attachment link is how the ASIF forum platform provides its own image upload and hosting service.
FWIW, my own opinion about 2007 is to agree with you from a different basis. It seems to me that the loss of multi-year ice in 2007 either reflected or helped initiate systemic changes in the ASI system. Various posts in the forum have described how, even though 2012 gets most of the attention since it holds the records, that when looked at from different points of view, 2007 was the Big Year. I have no hope of remembering in which thread, but (I think it was) Oren or BFTV who put up a post this summer listing losses from September to September which showed that when viewed from that time frame, 2007 outdistanced every other year for losses. So that's a second (but also not statistically validated) observation to lend weight to your proposition.
2012 had strong summer melt season weather topped off by perfectly timed and positioned cyclone to break up ice and pull subsurface heat to cause new low September minima. I don't have 2007 summer melt weather in my head, but I don't think it was as forceful as 2012, and certainly did not have a storm like the GAC 2012 to push it over the edge. Which leaves it up to other underlying changes that caused (at the time) new record lows.
My foggy recollection is that one contributing factor in 2007 was just enough extra floe mobility combined with conditions conducive for Farm or CAA export to send a lot of multi-year ice out of the central Arctic Ocean to its southern doom. I also think that the Beaufort Gyre faltered as the nursery for multi-year ice in 2007. Perhaps folks with a better handle on these fuzzy factoids can bolster or refute them, or add other lines of evidence about whether 2007 brought unique forces or outcomes to the ASI saga. After the unprecedented losses in 2007, there were journal article autopsies about what caused the losses observed that year. I don't have any specific links to share, but they exist.
As for photobucket. It sounds like you have Excel. You can make charts in Excel, save them as screen clips to Excel or Word, then click on the image and "Save as Image" to make a file copy on your hard drive. With that done, then when you write an ASIF post, use the Attachment link below the text box on the Reply screen to upload those saved chart images.
Sorry if that it is so blindingly obvious that you are wondering why I would bother to mention it. Here is why. I was messing around with different image hosting services until somebody on ASIF reminded me about the Attachment link on the Reply post form. I had not realized that was a way to upload images. Yet another in a lifetime of dope-slap to forehead moments, i.e. making something difficult that did not have to be. The Attachment link is how the ASIF forum platform provides its own image upload and hosting service.
39
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 12, 2020, 02:58:46 AM »
+2.7C per decade is Monstrous. It is more than 10X the rate of increase in NASA GISS (and other) measures of global average surface temperature. At risk of being one of those alarmists, +2.7 per decade looks like a possible break out from system equilibrium into scary out-of-control realignment to an entirely new climate regime. Maybe the fact that it is an October-only single-region value, and not the whole year/whole planet is some cause for not seeing this as an unfolding catastrophe. If it was a whole year planet-wide rate, we would be into Mad Max territory. Somebody who actually studies this stuff can correct me if I'm wrong, but +2.7C per decade (he says for the 3rd time in one paragraph) is absolutely nuts and unsustainable within the Holocene climate envelope upon which Human civilization is built and dependent. At that rate, the Laptev bite is going to be the CAB bite sooner than any of us ever foresaw.
Some people play fantasy football, I play nightmare planet by tracking NASA GISS and daily Climate Forecast System reports. Entering 2020, my magic predictive formula (which has been more accurate than UK Met and NASA GISS's Gavin Schmidt's prognostications over the last few years) called for 2020 to be several points (0.01 C units) below 2019, due to a weak ENSO signal and coming off of the bottom of the solar cycle. But as 2020 winds down, the current end-of-year-average projection has a 95.8% chance of beating 2019, and a 68% chance of topping 2016, the previous record-holder for warmest yearly global average surface temperature. Keep in mind that 2016 had a strong ENSO and a solar maximum pushing it up. The graph below shows the annual average GISS with ENSO/Solar/Aerosol forcings removed to see the underlying temperature without variation due to single-year forcings. (Too bad Tamino is not posting these days, it would be great to read his take on this).
The last time I sort-of looked, it was hard to see a correlation between annual GISS and ASI Extent/Area/Volume values. Of course, warming the planet as a whole eventually shows up in the Arctic. With La Nina kicking in for the next few months, that should put the brakes on GISS increase over the next six months at least, but I have no clue if that would show up in the Arctic or in the ASI stats. Remember that a cool La Nina year does not mean the Earth system is cooling, just that more heat is going into the ocean vs. the surface atmosphere than in an ENSO-neutral or El Nino year. Heat in the ocean has a bad habit of melting ice.
Looking ahead to 2021, based on the ENSO/Solar/Aerosol predictors, the GISS surface air temperature should be slightly cooler than 2020. But that is from the formula (that explained >80% of year-to-year variability... until 2020) that said 2020 should be cooler than 2019. The fact that my previously reliable formula failed in 2020 feeds my wonderings if Earth's thermostat is broken, and that the climate system is playing by new rules.
As for right now, the DMI 80N temperature is starting to look like the winter of 2016-2017 when there was a low accumulation of freezing degree days. Going out on the limb of my ignorance, I'll hazard a guess that for the near term at least, the recent above-average increases in Extent and Area could lose some momentum. If that DMI anomaly does not fall, it is easy to imagine a new record low maximum in spring 2021.
Some people play fantasy football, I play nightmare planet by tracking NASA GISS and daily Climate Forecast System reports. Entering 2020, my magic predictive formula (which has been more accurate than UK Met and NASA GISS's Gavin Schmidt's prognostications over the last few years) called for 2020 to be several points (0.01 C units) below 2019, due to a weak ENSO signal and coming off of the bottom of the solar cycle. But as 2020 winds down, the current end-of-year-average projection has a 95.8% chance of beating 2019, and a 68% chance of topping 2016, the previous record-holder for warmest yearly global average surface temperature. Keep in mind that 2016 had a strong ENSO and a solar maximum pushing it up. The graph below shows the annual average GISS with ENSO/Solar/Aerosol forcings removed to see the underlying temperature without variation due to single-year forcings. (Too bad Tamino is not posting these days, it would be great to read his take on this).
The last time I sort-of looked, it was hard to see a correlation between annual GISS and ASI Extent/Area/Volume values. Of course, warming the planet as a whole eventually shows up in the Arctic. With La Nina kicking in for the next few months, that should put the brakes on GISS increase over the next six months at least, but I have no clue if that would show up in the Arctic or in the ASI stats. Remember that a cool La Nina year does not mean the Earth system is cooling, just that more heat is going into the ocean vs. the surface atmosphere than in an ENSO-neutral or El Nino year. Heat in the ocean has a bad habit of melting ice.
Looking ahead to 2021, based on the ENSO/Solar/Aerosol predictors, the GISS surface air temperature should be slightly cooler than 2020. But that is from the formula (that explained >80% of year-to-year variability... until 2020) that said 2020 should be cooler than 2019. The fact that my previously reliable formula failed in 2020 feeds my wonderings if Earth's thermostat is broken, and that the climate system is playing by new rules.
As for right now, the DMI 80N temperature is starting to look like the winter of 2016-2017 when there was a low accumulation of freezing degree days. Going out on the limb of my ignorance, I'll hazard a guess that for the near term at least, the recent above-average increases in Extent and Area could lose some momentum. If that DMI anomaly does not fall, it is easy to imagine a new record low maximum in spring 2021.
40
Arctic sea ice / Re: River ice and Discharge
« on: November 09, 2020, 07:17:08 PM »
Thanks vox! Not just for the info but also relieving an annoying mental itch. I searched everywhere using "Lena". I should have used Mackenzie.
41
Arctic sea ice / Re: MOSAiC news
« on: November 09, 2020, 07:00:33 PM »
Nice graph gerontocrat! Any chance of getting a similar graph (and even better data table to go with it) for either the Central Arctic Seas or the CAB?
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Arctic sea ice / Re: River ice and Discharge
« on: November 09, 2020, 05:13:17 AM »https://www.researchgate.net/publication/339766641_Wind-Driven_Coastal_Upwelling_Near_Large_River_Deltas_in_the_Laptev_and_East-Siberian_SeasThere was another 2020 journal article 'somewhere' (maybe not ASIF) that discussed Siberian river heat discharge warming the Arctic Ocean. I've tried finding that other article without success. A link to it would be much appreciated.
“The Lena, Kolyma, and Indigirka rivers are among the largest rivers that inflow to the Arctic Ocean. Their discharges form a freshened surface water mass over a wide area in the Laptev and East-Siberian seas and govern many local physical, geochemical, and biological processes. In this study we report coastal upwelling events that are regularly manifested on satellite imagery by increased sea surface turbidity and decreased sea surface temperature at certain areas adjacent to the Lena Delta in the Laptev Sea and the Kolyma and Indigirka deltas in the East-Siberian Sea. These events are formed under strong easterly and southeasterly wind forcing and are estimated to occur during up to 10%–30% of ice-free periods at the study region. Coastal upwelling events induce intense mixing of the Lena, Kolyma, and Indigirka plumes with subjacent saline sea. These plumes are significantly transformed and diluted while spreading over the upwelling areas; therefore, their salinity and depths abruptly increase, while stratification abruptly decreases in the vicinity of their sources. This feature strongly affects the structure of the freshened surface layer during ice-free periods and, therefore, influences circulation, ice formation, and many other processes at the Laptev and East-Siberian seas.”
43
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 08, 2020, 08:06:46 PM »
And now we can add warm Siberian river drainage into the Arctic Ocean as another factor (article posted upthread). Given the record breaking high Siberian temperatures over land in summer 2020, the river water draining those areas must have been especially warm.
44
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: November 07, 2020, 10:19:26 PM »
Thanks kaixo, interesting perspective. Jim Pettit has graphic along similar idea, as does gerontocrat (but I can't find his version)
45
Arctic sea ice / Re: MOSAiC news
« on: November 05, 2020, 02:16:17 AM »<snip>How much will the long-delayed freeze-up affect ice growth during the winter (and ice quality going into melt season)? We have no idea how cold the air will be between now and then. However we do have reanalysis products up through early November plus daily ice thinness from Smos-Smap and even rate of growth from Cryo2Smos.Great info A-Team. It would be great to have an average age metric to add to an Arctic Sea Ice Multi Metric Index. It seems like that info is embedded in the data used to create the ice age map. Specifically, do those data allow conversion into a daily "average ice days" value across a grid cell map of the Arctic Ocean, or the central Arctic seas? Or at least the CAB?
It's also feasible to make a map showing how many days each point in the Arctic Ocean has had an ice cover and what the 'deficiency' has been this season given the Laptev, ESS and Chukchi open water anomaly. <snip>----etc.
Do you think that average ice days would carry within it some proxy/correlated information about salinity or other characteristics that affect melt resistance? Thickness already does that to some degree, but I think it does so incompletely. That is because I suspect that not all ice of the same Thickness has equal physical characteristics or melt resistance. My guess is that 2-meter ice that has been around for a while and thus had more time to expel salt content or get compressed by pack motion is different than younger 2-meter thick ice.
Just a bunch a notions and questions from an amateur ASI watcher who does not know the details but looking for patterns. Thanks for your contributions to our understanding this very complex system.
46
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: October 31, 2020, 10:53:15 PM »current Siberian anomaly for example ? .. https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=3299.0;attach=290316;imageYou got me on that one! I was focused on global year-round land vs ocean warming. I look at the Arctic Ocean temp. anomaly on CR regularly, so you'd think the ocean vs land difference would have sunk in. Useful to be reminded of my ability to misperceive or misplace evidence.
47
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: October 31, 2020, 10:21:51 PM »
That temperature map is not convincing. A temperature map of the Arctic Ocean and surrounding landmass is needed, not a side view with the Arctic gets crushed into a thin slice at the top. From what I recall Siberian land temperatures have frequently been 10C or more above historical norms in 2020 vs. Siberian sea temperature anomalies much lower than that. So based on that larger net difference, I would say Siberian land mass is warming faster than Siberian seas.
Again, the whole field is out of my league, so I have no opinion about how relative land vs sea temperatures might affect air pressure distribution, variability, timing, or resulting weather. I'm just questioning the assertion that Siberian seas are warming faster than land. On a global basis that is not the case, so it would be odd for the Arctic to follow a different pattern. But I just re-read your original message, and your hypothesis does not require seas to be warming more than land, just that cold air coming off of land now overlays seas that were warmer than they used to be. Which is certainly the case for open water vs. ice covered sea. So I'm outta here!
Again, the whole field is out of my league, so I have no opinion about how relative land vs sea temperatures might affect air pressure distribution, variability, timing, or resulting weather. I'm just questioning the assertion that Siberian seas are warming faster than land. On a global basis that is not the case, so it would be odd for the Arctic to follow a different pattern. But I just re-read your original message, and your hypothesis does not require seas to be warming more than land, just that cold air coming off of land now overlays seas that were warmer than they used to be. Which is certainly the case for open water vs. ice covered sea. So I'm outta here!
48
Arctic sea ice / Re: Atmospheric connections, structure, and long range weather forecasting
« on: October 31, 2020, 05:19:15 PM »
El Cid - you asked for comments, so here goes from someone who knows little about the air mass dynamics. Even with the Siberian seas warming, it seems that the net difference and thus interaction between the Siberian seas and the very cold Siberian land mass in winter may not change that much, or may change in the other direction.
With a more insulating CO2-enhanced atmosphere, the winter land mass must also be warming by as much or more than the Siberian seas are warming. Globally, land masses are warming faster than the oceans. So presumably that is also true around the Arctic Ocean. If so, how does that affect your hypothesis?
With a more insulating CO2-enhanced atmosphere, the winter land mass must also be warming by as much or more than the Siberian seas are warming. Globally, land masses are warming faster than the oceans. So presumably that is also true around the Arctic Ocean. If so, how does that affect your hypothesis?
49
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 31, 2020, 04:46:29 PM »<snip> The fall season is peak Arctic Amplification,My understanding is that Arctic amplification is primarily due to less ice Extent --> albedo decline --> more sunlight energy absorption by dark open water --> warmer water --> more ice melt --> less ice Extent. With very little sunlight reaching the Arctic at this time of year, how is it that fall is "peak Arctic amplification"?
I suppose more open water also creates more moisture in the air and thus a thicker insulating blanket to retain heat emitted by the open water, thus another reinforcing feedback. But albedo change seems to be the most important forcing change caused by Arctic warming, and that change in net forcing should decline to near nothing in the fall. So I don't understand how fall could be peak amplification unless "amplification" is a noun that refers to the observable impacts, not as a verb that describes additional forcing contributions.
Thanks to Oren for "moderating." I'm one of the 1783 ASIF members with no training in Arctic science or climatology. I come here to learn and see what's happening in what is arguably the most consequential observable event in human history - the degradation of the Arctic sea ice. I do work with weather and crop pests, and one of these days I suppose I could learn how to work with netCDF files, but it will never happen. I have a colleague who does that. But he doesn't know much about managing insects and diseases that attack crops. So we each do our part. We can't each do everything. It's better if I let him handle the netCDF programming so I can focus on keeping up with the biological developments from my reading of the relevant information from about 1% up to maybe 2%.
The world is a complicated place. It's great that we have access to so much information. But it is also overwhelming, so we have to pick our spots. Adding buoy analysis is not the right move for me or for bettering the world. Scolding me about it is not going to change that.
I wish we had 1.7 billion people in the ASIF watching and worrying about the Arctic, whether or not they ever post any data analysis. ASIF plays an important role in raising awareness, which is a necessary prerequisite for solutions. I know at least one prominent journalist aware of the ASIF, and I'm sure there are many others. I hope ASIF remains an open conversation that welcomes all and brings attention to the climate crisis.
And it IS a crisis even though for political purposes it seems to move too slow to meet that definition. The faster that train rolls the less we can do about it. It's already moving, and 30 more years of acceleration is already baked into the cake. It's like Dr. Fauci said about COVID-19, if you think you are here (low on the curve), you are really here (farther along and higher on the curve). So you have to act accordingly. Our house is on fire. We need to support each other in whatever capacity we each have to attack the problem, not each other.
50
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 30, 2020, 12:36:16 AM »
FWIW - The edited chart below shows how an NSIDC maximum Extent would compare to other years if refreeze from Oct 28 followed the highest rate in most recent 13 years until reaching a maximum in March 2021. Based on JAXA values posted by gerontocrat:
https://forum.arctic-sea-ice.net/index.php/topic,2975.msg291409.html#msg291409
To create the hypothetical NSIDC max I increased the extrapolated JAXA max by 0.41 M km2 to account for the difference between JAXA and NSIDC record lows. (The extrapolated JAXA low would be 13.49).
Extent value is an incomplete metric to represent the complexity of ASI condition. Additional dimensions (Area, Volume) and qualitative characteristics (Thickness, salinity, mechanical strength, snow cover, temperature?, density?) are missing from a simple measure of maximum Extent. In addition to ice measures, it seems that emerging changes in the Arctic Ocean (open water, wave action, water temperature, thermo-halocline stability, Atlantification, currents, storm potential, less ice pack cohesion with greater floe mobility, and more) are almost all on the side of working against ice retention, not promoting it (a possible exception being jet stream changes described by Francis and Wu 2020, https://forum.arctic-sea-ice.net/index.php/topic,2692.msg291501.html#msg291501)
Thus, even if the resulting maximum Extent is closer to (or above) the trend line, the 2021 maximum Extent value, whatever it is, will be for ice that on average is almost certainly less resistant to melt than even the most recent historical norm as it heads into the 2021 melt season.
It must also be noted that when the long term trend is extracted, the annual maximum Extent has almost no predictive power for the subsequent September minimum. A dramatically low March maximum at the beginning of the melt season does not tell us what to expect at the end of the melt season.
But with the expected effects of late refreeze on ice quality and melt resistance, I wonder if that previous lack of correlation between preceding maximum to the subsequent minimum will continue. Compounding effects of qualitative decline may emerge from the noise of year-to-year variability to become a separate and identifiable (and measurable, monitored, and reported?) influence. Just guesswork inspired by hypotheticals.
https://forum.arctic-sea-ice.net/index.php/topic,2975.msg291409.html#msg291409
To create the hypothetical NSIDC max I increased the extrapolated JAXA max by 0.41 M km2 to account for the difference between JAXA and NSIDC record lows. (The extrapolated JAXA low would be 13.49).
Extent value is an incomplete metric to represent the complexity of ASI condition. Additional dimensions (Area, Volume) and qualitative characteristics (Thickness, salinity, mechanical strength, snow cover, temperature?, density?) are missing from a simple measure of maximum Extent. In addition to ice measures, it seems that emerging changes in the Arctic Ocean (open water, wave action, water temperature, thermo-halocline stability, Atlantification, currents, storm potential, less ice pack cohesion with greater floe mobility, and more) are almost all on the side of working against ice retention, not promoting it (a possible exception being jet stream changes described by Francis and Wu 2020, https://forum.arctic-sea-ice.net/index.php/topic,2692.msg291501.html#msg291501)
Thus, even if the resulting maximum Extent is closer to (or above) the trend line, the 2021 maximum Extent value, whatever it is, will be for ice that on average is almost certainly less resistant to melt than even the most recent historical norm as it heads into the 2021 melt season.
It must also be noted that when the long term trend is extracted, the annual maximum Extent has almost no predictive power for the subsequent September minimum. A dramatically low March maximum at the beginning of the melt season does not tell us what to expect at the end of the melt season.
But with the expected effects of late refreeze on ice quality and melt resistance, I wonder if that previous lack of correlation between preceding maximum to the subsequent minimum will continue. Compounding effects of qualitative decline may emerge from the noise of year-to-year variability to become a separate and identifiable (and measurable, monitored, and reported?) influence. Just guesswork inspired by hypotheticals.