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Thread: Sea Ice

  1. #31
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    Quote Originally Posted by Torsten View Post

    I made the following chart from monthly data acquired from NSIDC:



    The maximum amount of ice

    snip...

    indicator of anything.
    Quote Originally Posted by Torsten View Post
    Quote Originally Posted by William
    Plot the data, global anomaly, Southern Polar, Northern Polar, Southern Polar, Southern Hemisphere, Northern Hemisphere, and tropics. Add a trend line to each of the plots.
    I find this suggestion to plot data humorous, because in all the years we've been discussing these topics I cannot remember you linking even once to a chart that you yourself have made from data found online.
    Quote Originally Posted by Torsten View Post
    Okay. The following rationale

    snip...

    this method overestimated the amount of September ice extent.

    So, my prediction is for 4.45 +/- 0.90 million square km average ice extent for September 2012, as reported by NSIDC. The error range may seem wide, but that's the best I can do with this method.



    Now, how about you provide us with a hard estimate?
    Nice work, Torsten.

  2. #32
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    In the last five days the arctic sea ice extent as measured by the AMSR2 sensor has fallen by almost 500,000 km2.

    Check out the freefall.

    My simple statistical model quoted above by Tensor assumes all ice is equal, but in reality it has been thinning for years. Earlier this month it was really beaten up by a storm, (which probably would not have happened with a thicker pack) and it looks like September will start with an extent of less than 4 million km2. Last year, there was almost 500,000 km2 ice extent loss between the start of September and the 9th, when the minimum was achieved. In 2007, the minimum was reached on September 24, but the loss during September was ~350,000 km2. I don't know what to make of this, and I wonder if the average extent reported by NSIDC for September will even lie within my error range. I had a suspicion something like this could happen, which was why I made the point that the model overestimated the value more often than it underestimated it.

    Only three weeks ago, at a blog where I sometimes comment, I revised my prediction for NSIDC September average down to 4.35 million km2, using the July ratio of extent to area as an additional variable in my regression (the assumption being that this ratio is a measure of the state of decay of the pack and its vulnerability to further melt in August). My prediction for the minimum daily value for extent reported by NSIDC in September was 4.15 million km2, and we're already below that.

    But what I really want to know is whether the OP, if he still reads these threads, has any comment on this. I notice that WUWT (I won't provide a link to that... place) is silent on the topic. WUWT? - indeed.

  3. #33
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    General current prediction is that the arctic sea ice will drop below the 2007 minimum which was the previous lowest extent.

    More in this article which also has larger versions of the graph.

    Figure2Aug13-350x280.png
    Image courtesy of the National Snow and Ice Data Center, University of Colorado, Boulder.
    Last edited by HenrikOlsen; 2012-Aug-27 at 07:27 AM. Reason: replaced with reference to original article
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  4. #34
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    Quote Originally Posted by Torsten View Post
    In the last five days the arctic sea ice extent as measured by the AMSR2 sensor has fallen by almost 500,000 km2.

    ...

    But what I really want to know is whether the OP, if he still reads these threads, has any comment on this. I notice that WUWT (I won't provide a link to that... place) is silent on the topic. WUWT? - indeed.
    Actually WUWT has a sea ice page and you can follow it there. It has about two weeks more data than Henrik's chart (it's linked to the NSIDC site) and it shows we have matched 2007 about two weeks earlier than the 2007. I really think you will see something posted on WUWT when it drops below 2007. The key thing to remember is the history of the data only goes back to 1979; something that somehow gets lost in the news.

  5. #35
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    I remembered this from post #19 and #24:

    Quote Originally Posted by William
    Tensor is missing the obvious, that it does not seem possible to isolate cooling to Svalbard. Long term data is only available at Svalbard. Svalbard cooled in the past after a 10 to 12 year delay when there was a change in the length of the solar magnetic cycle. There was in the winter 2011/2012 the largest extent of ice ever measured in the Bering sea.
    I pointed out that in 2010-2011, the wind was blowing ice into the harbor at Svalbard. This cooled the air around the Harbor and dropped the temperature more than normal. This past winter, in the Bering Sea, the large ice cover was due to the wind blowing in from the north and northwest, which blew the sea ice south, which lead to the large ice cover(Thank you "Deadliest Catch"). Note that it was the wind, blowing the ice that caused the problems in both the Harbor at Svalbard and in the Bering Sea. Also note that the two events were not in the same winter, which pretty much destroy's the OP's contention that you can't separate different high latitude events. Local weather conditions can and do influence data points in long term trends, without changing the trend.

  6. #36
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    See also today's blog post by the Bad Astronomer.
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  7. #37
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    Quote Originally Posted by Trebuchet View Post
    See also today's blog post by the Bad Astronomer.
    Looking at this map:

    http://nsidc.org/data/seaice_index/i...tent_hires.png

    I can see why Phil Plait is unhappy.

    The change from the 1979-2000 average extent is significant.

    James Hansen and others have predicted record warm global average temperatures for the next several years, this raises the possibility of an ice free Arctic by the middle of this decade. As Phil states, the ice-albedo feedback will accelerate the melting.

    The most worrisome aspect of this to me is how this accelerates. Ice is bright white, so it reflects sunlight. Sea water is much darker and absorbs that light. So the more ice you lose, the darker overall the arctic gets, and the faster it melts.

  8. #38
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    Quote Originally Posted by orionjim View Post
    Actually WUWT has a sea ice page and you can follow it there. It has about two weeks more data than Henrik's chart (it's linked to the NSIDC site) and it shows we have matched 2007 about two weeks earlier than the 2007. I really think you will see something posted on WUWT when it drops below 2007. The key thing to remember is the history of the data only goes back to 1979; something that somehow gets lost in the news.
    Yeah, he's got a good collection of charts there, but I've bookmarked a different compilation page.

    I've tried writing several different things about the comments he made today, but I fear the comments I want to make are inflammatory, so I'll just say I'm unimpressed.

    Apparently, a University of Bremen team has been able to use satellite data from as early as 1972.

    And there is this chart going back to 1900, but I've read elsewhere that the records after 1950 are much more complete than prior to that.

  9. #39
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    Quote Originally Posted by orionjim View Post
    The key thing to remember is the history of the data only goes back to 1979; something that somehow gets lost in the news.
    Which means that this graph from the Arctic Sea Ice Blog are even more alarming. The Aug 1 average volume of ice in the 1980s was ~18,000 km3. Now look at the volume for the same date in 2012, ~6,000 km3. Dropping 66% of the total volume over only 33 years, when the icepack was at least at it's 1979 extent for the previous ~120,000 years is way outside any kind of natural time frame The most generous estimates for the last time the arctic was ice free was ~120,000 years ago, during the height of the Eemian interglacial which ran ~130,000 - ~114,000. it took at least 6,000 years for the Arctic to be ice free (studies that indicate that the Arctic was ice free at this time, also indicate that it was ice covered prior to the Eemian. Other estimates for the Arctic to be ice free run from ~700,000 years ago to over 4 Million years ago, which would mean the Arctic was ice covered for even longer.

    Also note that that the current year is running less than last year, which means that at lowest extent this year, the Arctic ice could be as low as 4-5,000 km3, or the ice volume has possibly shrunk as much as 75% in 33 years, at minimum value.

  10. #40
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    Quote Originally Posted by orionjim View Post
    The key thing to remember is the history of the data only goes back to 1979; something that somehow gets lost in the news.
    You're forgetting the people tried sailing those waters quite a lot earlier than 1979, just check the history of the North West passage.
    We don't have satellite measurements before, but we to have a much longer history of data albeit with less detail.
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  11. #41
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    Here are some papers of sea ice observations (global, Arctic, Antarctic):

    http://agwobserver.wordpress.com/200...-observations/

    Just yesterday I updated some older papers there showing that Arctic sea ice extent was active research area alreadyin 1970's and 1980's. For example there is a paper from 1979 reporting a data set from 1901 to 1956. (I have to update the list to contain more recent papers, though.)

  12. #42
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    Quote Originally Posted by Torsten View Post
    ...

    I've tried writing several different things about the comments he made today, but I fear the comments I want to make are inflammatory, so I'll just say I'm unimpressed.

    ...
    Well that makes two of us. I wasnít impressed with what they had to say either and Iím sure the reasons Iím not impressed are the same as yours.

  13. #43
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    Quote Originally Posted by orionjim View Post
    Actually WUWT has a sea ice page and you can follow it there. It has about two weeks more data than Henrik's chart (it's linked to the NSIDC site) and it shows we have matched 2007 about two weeks earlier than the 2007. I really think you will see something posted on WUWT when it drops below 2007. The key thing to remember is the history of the data only goes back to 1979; something that somehow gets lost in the news.
    We matched 2007 the day before yesterday, Sunday the 26. august, and are now into record low since detailed measurements started.
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  14. #44
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    There is a new entry on the Arctic Sea Ice Blog entitled, "Record dominoes 9: PIOMAS sea ice volume". Short version, PIOMAS did an extra data release due to the Labor Day holiday in the US. As of Aug 25, the ice volume is below 4,000 km3 for the first time in recorded history. The next update will probably be sometime this coming week. This update will include all of August's data. And we still have two to three weeks before the normal time for the yearly minimum.

  15. #45
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    A question about this; one of the important variables is the amount of cold fresh water released by the melting arctic ice, which is thought to affect the gulf stream in north atlantic. If there is less total ice each year is the absolute amount of this cold fresh water increasing or decreasing each year?

  16. #46
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    Quote Originally Posted by profloater View Post
    A question about this; one of the important variables is the amount of cold fresh water released by the melting arctic ice, which is thought to affect the gulf stream in north atlantic. If there is less total ice each year is the absolute amount of this cold fresh water increasing or decreasing each year?
    That might depend on how much the Greenland glaciers are also melting. This is a lot more ice (~2.8 million cubic kilometers) on Greenland than there is in Arctic Sea Ice (~3.3 thousand cubic kilometers). The number for the sea ice was as of September 1 and the low point is still about a week away. The number for Greenland is probably a lower due to the large amount of summer melt this year. It's tough to pin down comparison numbers with moving targets. With the melting of the Greenland Ice Sheet, I would say the amount of fresh water is increasing.

  17. #47
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    Quote Originally Posted by Tensor View Post
    That might depend on how much the Greenland glaciers are also melting. This is a lot more ice (~2.8 million cubic kilometers) on Greenland than there is in Arctic Sea Ice (~3.3 thousand cubic kilometers). The number for the sea ice was as of September 1 and the low point is still about a week away. The number for Greenland is probably a lower due to the large amount of summer melt this year. It's tough to pin down comparison numbers with moving targets. With the melting of the Greenland Ice Sheet, I would say the amount of fresh water is increasing.
    Thank you Tensor, that is interesting and of course the mechanism for Greenland ice melt cannot include the warmer arctic ocean which melts the ice cap from underneath. The rate of slide of the glacier however is crucial since once calved off the icebergs join the fresh water equation.

  18. #48
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    Arctic sea ice reaches lowest extent for the year and the satellite record
    Arctic sea ice cover likely melted to its minimum extent for the year on September 16, according to scientists at the National Snow and Ice Data Center (NSIDC). Sea ice extent fell to 3.41 million square kilometers (1.32 million square miles), now the lowest summer minimum extent in the satellite record.

    “We are now in uncharted territory,” said NSIDC Director Mark Serreze.

  19. #49
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    NSIDC scientist Julienne Stroeve said, “Recent climate models suggest that ice-free conditions may happen before 2050, though the observed rate of decline remains faster than many of the models are able to capture.”

    Serreze said, “While lots of people talk about opening of the Northwest Passage through the Canadian Arctic islands and the Northern Sea Route along the Russian coast, twenty years from now from now in August you might be able to take a ship right across the Arctic Ocean.”
    If we're down to less than 4,000 km^3 of ice volume from a high of about 18,000 km^3 30 years ago then I think this is a very conservative prediction. It's possible sea ice will be gone in the Arctic in the late summer within this decade, I think likely is a better word.

  20. #50
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    Is the sea ice melt mostly related to solar forcing locally or a general rise in temperature or is it due to weather systems bringing warmer air to the arctic? I wonder because climate change is often looked at as a steady and gradual process and it seems that in reality weather can play a major factor over a short timescale.
    Et tu BAUT? Quantum mutatus ab illo.

  21. #51
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    Quote Originally Posted by Ara Pacis View Post
    Is the sea ice melt mostly related to solar forcing locally or a general rise in temperature or is it due to weather systems bringing warmer air to the arctic? I wonder because climate change is often looked at as a steady and gradual process and it seems that in reality weather can play a major factor over a short timescale.
    I'm not sure, it's probably a combination of those factors. More local forcing due to increased GHGs and more warm air masses and higher ocean temperatures as a result of overall global warming.

  22. #52
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    Quote Originally Posted by Ara Pacis View Post
    Is the sea ice melt mostly related to solar forcing locally or a general rise in temperature or is it due to weather systems bringing warmer air to the arctic? I wonder because climate change is often looked at as a steady and gradual process and it seems that in reality weather can play a major factor over a short timescale.
    actually it is a little of all. due to the seasonal effects with the sun being above the horizon 24 hours a day the greenhouse effect is rather more prominent at the poles than around the equatorial regions. This leads to greater summer warming, as well as less winter cooling during the polar winter. the current wethar patterns also bring warm wet air in from further south.

    What is the bigger concern for us in northern europe is the adverse effect this may indeed have on the gulf stream that brings warm water up north along the european coastline, thus giving us the nice mild winters we are generally used to. we have already started seeing an increase in the number and length of cold-snaps during the winter season here. as well as a general increase in precipitation due to the higher evaporation rates from warmer southern oceans. it's a heat exchange system really. with the gulf giving us not only a warmer climate than we would otherwise get, but it also is the source of all our rainfall. and we have lots and lots of that already I can tell you.

    I do not like the implications of an ice free arctic. it can lead to some pretty extreme weather going by some of the weather models our meteorologists work with in order to try to predict future weather trends. whatever actually happens it promises to be a pretty bumpy ride.

  23. #53
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    Quote Originally Posted by Antice View Post
    I do not like the implications of an ice free arctic. it can lead to some pretty extreme weather going by some of the weather models our meteorologists work with in order to try to predict future weather trends. whatever actually happens it promises to be a pretty bumpy ride.
    This doesn't sound good.

    http://thinkprogress.org/climate/201...ves/?mobile=nc

    The study shows that by changing the temperature balance between the Arctic and mid-latitudes, rapid Arctic warming is altering the course of the jet stream, which steers weather systems from west to east around the hemisphere. The Arctic has been warming about twice as fast as the rest of the Northern Hemisphere, due to a combination of human emissions of greenhouse gases and unique feedbacks built into the Arctic climate system.

    The jet stream, the study says, is becoming “wavier,” with steeper troughs and higher ridges. Weather systems are progressing more slowly, raising the chances for long-duration extreme events, like droughts, floods, and heat waves.

  24. #54
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    I heard a bit on NPR the other night. They were talking about the implications of an ice-free Arctic on shipping. IIRC, there were something like 60 ships that tested using the Arctic as a shipping route this past summer, and it is expected that this will increase.

    There are some environmental concerns. One is that the soot released by the diesel exhaust from the ships could deposit on the remaining ice, making it darker, and thus it would absorb more heat and melt even faster. On the flip side, the shorter routes that a trans-Arctic route provides (IIRC, it was 1/3 shorter for some routes) would lead to less CO2 production for the same amount of shipped goods.
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  25. #55
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    Here's some interesting graphic views of the changes in the Arctic this summer:

    http://www.flickr.com/photos/gsfc/8003901788/

    http://www.washingtonpost.com/blogs/...e190_blog.html

    More open water means higher temperatures, more evaporation and likely more storms which can break up already thinning ice packs and drive the ice into warmer waters where it melts much faster.

    NASA says a large Arctic storm in early August played a role in the record low extent.

    “The storm cut off a large section of sea ice north of the Chukchi Sea and pushed it south to warmer waters that made it melt entirely,” NASA wrote. “It also broke vast extensions of ice into smaller pieces more likely to melt.”
    http://www.nasa.gov/topics/earth/fea...seaicemin.html

  26. #56
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    Quote Originally Posted by starcanuck64 View Post
    This doesn't sound good.

    http://thinkprogress.org/climate/201...ves/?mobile=nc
    The study shows that by changing the temperature balance between the Arctic and mid-latitudes, rapid Arctic warming is altering the course of the jet stream, which steers weather systems from west to east around the hemisphere. The Arctic has been warming about twice as fast as the rest of the Northern Hemisphere, due to a combination of human emissions of greenhouse gases and unique feedbacks built into the Arctic climate system.

    The jet stream, the study says, is becoming “wavier,” with steeper troughs and higher ridges. Weather systems are progressing more slowly, raising the chances for long-duration extreme events, like droughts, floods, and heat waves.
    That's what I was thinking about. A meridional flow (north to south) that gets steeper and reaches farther north could bring a lot of arm air up to the ice sheets causing them to melt/calve more rapidly than a steady climate change model might suggest. The idea of smooth deglaciation made sense to be at one time, when I thought most glacial motion was by sliding along rocks, but a lot of the motion is by a leaning or rolling motion, where the ice deforms forward over the slower moving ice that's stuck to the rock (if it's on bedrock and not slippery regolith)
    Et tu BAUT? Quantum mutatus ab illo.

  27. #57
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    If you look at where the most stable core of the Arctic sea ice is there's serious implications for the Greenland Ice Sheet for when(not if) the Arctic becomes ice free at the summer minimum. Instead of the insulating effect of having sea ice to the north, Greenland will have open sea water which will increase the amount of solar energy absorbed locally, the amount of water vapor in the atmosphere and the movement of warm air masses over Greenland and probably rainfall there.

  28. #58
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    Quote Originally Posted by starcanuck64 View Post
    If you look at where the most stable core of the Arctic sea ice is there's serious implications for the Greenland Ice Sheet for when(not if) the Arctic becomes ice free at the summer minimum. Instead of the insulating effect of having sea ice to the north, Greenland will have open sea water which will increase the amount of solar energy absorbed locally, the amount of water vapor in the atmosphere and the movement of warm air masses over Greenland and probably rainfall there.
    well.. i have calculated that the farm i live on will become a beach property if all that Greenland ice melts. I'd have to say that i kinda prefer the sea level to remain approximately where it's at right now. so how about we stop burning them hydrocarbons already thankyouverymuch.

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    Quote Originally Posted by starcanuck64 View Post
    If you look at where the most stable core of the Arctic sea ice is there's serious implications for the Greenland Ice Sheet for when(not if) the Arctic becomes ice free at the summer minimum. Instead of the insulating effect of having sea ice to the north, Greenland will have open sea water which will increase the amount of solar energy absorbed locally, the amount of water vapor in the atmosphere and the movement of warm air masses over Greenland and probably rainfall there.
    I recall reading that sea ice also buttresses the Greenland glaciers, so missing sea ice means faster calving. Also, increased precip, even as snow, on top of the ice domes on Greenland increases the weight and thus the outward pressure and causes the glaciers to move faster.
    Et tu BAUT? Quantum mutatus ab illo.

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    Quote Originally Posted by Antice View Post
    well.. i have calculated that the farm i live on will become a beach property if all that Greenland ice melts. I'd have to say that i kinda prefer the sea level to remain approximately where it's at right now. so how about we stop burning them hydrocarbons already thankyouverymuch.
    I calculated that if all the ice melted, there'd be "ocean-front property in Arizona." You won't be able to catch the 3:10 to Yuma unless it's submersible.
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