Guest post by David Middleton
Anthony recently posted an excellent Arctic sea ice analysis by Ron Clutz. In a similar vein, I decided to look at Arctic sea ice from a couple of other dis-alarming perspectives.
We keep hearing about the Arctic being ice-free anytime from next month up until a continuously rolling forward decade or so. One question that has to be answered is:
What does ice-free mean?
When does ice-free mean ice-free?
First, we need to clarify what exactly an “ice-free” Arctic summer is.
By “ice-free”, scientists usually mean a sea ice extent of less than one million square kilometres, rather than zero sea ice cover.
–Dr Alexandra Jahn, Assistant Professor in the Department of Atmospheric and Oceanic Sciences and Fellow at the Institute of Arctic and Alpine Research at the University of Colorado. Carbon Brief, August 25, 2016.
Why use extent rather than area?
What is the difference between sea ice area and extent?
Area and extent are different measures and give scientists slightly different information. Some organizations, including Cryosphere Today, report ice area; NSIDC primarily reports ice extent. Extent is always a larger number than area, and there are pros and cons associated with each method.
A simplified way to think of extent versus area is to imagine a slice of swiss cheese. Extent would be a measure of the edges of the slice of cheese and all of the space inside it. Area would be the measure of where there is cheese only, not including the holes. That is why if you compare extent and area in the same time period, extent is always bigger. A more precise explanation of extent versus area gets more complicated.
Extent defines a region as “ice-covered” or “not ice-covered.” For each satellite data cell, the cell is said to either have ice or to have no ice, based on a threshold. The most common threshold (and the one NSIDC uses) is 15 percent, meaning that if the data cell has greater than 15 percent ice concentration, the cell is considered ice covered; less than that and it is said to be ice free. Example: Let’s say you have three 25 kilometer (km) x 25 km (16 miles x 16 miles) grid cells covered by 16% ice, 2% ice, and 90% ice. Two of the three cells would be considered “ice covered,” or 100% ice. Multiply the grid cell area by 100% sea ice and you would get a total extent of 1,250 square km (482 square miles).
Area takes the percentages of sea ice within data cells and adds them up to report how much of the Arctic is covered by ice; area typically uses a threshold of 15%. So in the same example, with three 25 km x 25 km (16 miles x 16 miles) grid cells of 16% ice, 2% ice, and 90% ice, multiply the grid cell areas that are over the 15% threshold by the percent of sea ice in those grid cells, and add it up. You would have a total area of 662 square km (255.8 square miles).
Scientists at NSIDC report extent because they are cautious about summertime values of ice concentration and area taken from satellite sensors. To the sensor, surface melt appears to be open water rather than water on top of sea ice. So, while reliable for measuring area most of the year, the microwave sensor is prone to underestimating the actual ice concentration and area when the surface is melting. To account for that potential inaccuracy, NSIDC scientists rely primarily on extent when analyzing melt-season conditions and reporting them to the public. That said, analyzing ice area is still quite valuable. Given the right circumstances, background knowledge, and scientific information on current conditions, it can provide an excellent sense of how much ice there really is “on the ground.”
Arctic sea ice as a percentage of the area of the Arctic Ocean
The Arctic Ocean has a surface area of approximately 14,056,000 km2. An ice-free Arctic would be less than 1,000,000 km2 of sea ice extent during summet. This would equate to less than 7% of the Arctic Ocean’s surface area.
During the era of satellite measurements of Arctic sea ice, the minimum ice extent has always occurred in September and the maximum extent has almost always occurred in March, occasionally in February.
| March (1979-2008 Avg) | Min | Max |
| 110% | 102% | 116% |
| Sept (1979-2008 Avg) | Min | Max |
| 47% | 25% | 55% |
Try to process logically process this:
The 1970’s Arctic sea ice extent range of 55-116% of the area of the Arctic Ocean gave us this:
Whereas, the 2017-2018 Arctic sea ice range of 35-102% of the area of the Arctic Ocean gave us this:
The stupid literally could not burn any brighter.
Here’s the graph without funny magazine covers…
And here’s my spreadsheet:
Sea_Ice_Index_Monthly_Data_by_Year_G02135_v3.0_Modified_DHM
Arctic sea ice in the context of the Holocene
The Arctic was probably ice-free during summer for most of the Holocene up until about 1,000 years ago. McKay et al., 2008 demonstrated that the modern Arctic sea ice cover is anomalously high and the Arctic summer sea surface temperature is anomalously low relative to the rest of the Holocene.
Over most of the Holocene, >50% sea ice coverage occurred from 5.5 to 9 months each year. During the “Anthropocene”, >50% sea ice coverage has ranged from 9 to 12 months each year.
Conclusion
References
Fetterer, F., K. Knowles, W. Meier, M. Savoie, and A. K. Windnagel. 2017, updated daily. Sea Ice Index, Version 3. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/10.7265/N5K072F8. [Accessed September 26, 2018].
- ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis
- ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Monthly_Data_by_Year_G02135_v3.0.xlsx
McKay, J.L., A. de Vernal, C. Hillaire-Marcel, C. Not, L. Polyak, and D. Darby. 2008. Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea. Can. J. Earth Sci. 45: 1377–1397
still tics me off…..every graph always starts at the bottom of the AMO
And right after the PDO switched from cold to warm (Pacific Climate Shift of 1976)… Unfortunately, that’s where the satellite data begin.
Not sure if you are aware…
IPCC AR2 WG1 page 137 states that satellite sea ice observations began in 1973.
This is also stated in IPCC AR1 WG1 page 224 with a graph in the upper right of that page.
1979 is now used as the starting point because it is a maximum for sea ice extent.
Thanks to Tony Heller for pointing this out.
I did not know that… But I’m not surprised.
David,
Both the IPCC FAR (1990) and SAR (1995) published graphs of Sea Ice Extent (minimum 10%,) attributing the data to NOAA, and showing graphed results beginning in 1973. Those NOAA data were based off Passive Microwave sounder data from satellites. Winter 1973-1974 had anomalies as far below average (about -.85 10^6 sq km) as those in 1978-’79 did above average. The next season when equivalent low anomalies got to the same level was 1984.
Here is what the FAR text shows on p 224, right column, immediately below the graphs:
‘Sea-ice conditions are now reported regularly in marine
synoptic observations, as well as by special reconnaissance
flights, and coastal radar. Especially importantly, satellite
observations have been used to map sea-ice extent
routinely since the early 1970s. The American Navy Joint
Ice Center has produced weekly charts which have been
digitised by NOAA. These data are summarized in Figure
7.20 which is based on analyses carried out on a 1° latitude
x 2.5° longitude grid. Sea-ice is defined to be present when
its concentration exceeds 10% (Ropelewski, 1983). Since
about 1976 the areal extent of sea-ice in the Northern
Hemisphere has varied about a constant climatological
level but in 1972-1975 sea-ice extent was significantly less.’
What changed at the end of the 1970s was due to the new generation of satellites, and a new methodology evaluating ice at minimum of 15% concentration. Both the FAR and the SAR used 10%, which is not directly comparable, without going back and doing a re-analysis.
+42
That graph goes up to 1990 and there is no mention of a methodology change in the middle of it. I am aware that minimum 15% concentration is currently used.
Was there a period from 1979 to 1990 (or so?) where both methodologies were in operation and the old system was used in AR1? Or did they just switch methodologies without stating it?
David A Smith,
The methodological details were not disclosed in an IPCC report until the TAR, 2001. In section 2.2.5.2, which begins on section 2, page 124, is the following text:
‘Sea-ice extent (the area within the ice-ocean margin) was
observed from space from 1973 to 1976 using the ESMR
(Electrically Scanning Microwave Radiometer) satellite-based
instrument, and then continuously from 1978 using the SSMR
(Scanning Multichannel Microwave Radiometer) (1978 to 1987)
and SSM/I (Special Sensor Microwave/Imager) (1987 to present).
By inter-calibrating data from different satellites, Bjørgo
et al.(1997) and subsequently Cavalieri et al. (1997) obtained uniform
monthly estimates of sea-ice extent for both hemispheres from
November 1978 through to December 1996. Over this period, the
sea-ice extent over the Northern Hemisphere showed a decrease of
−2.8 ±0.3%/decade (Parkinson et al., 1999), consistent with
Johannessen et al. (1995) (Figure 2.14). The Arctic decrease was
strongest in the Eastern Hemisphere and most apparent in summer
(Maslanik et al., 1996; Parkinson et al., 1999). ‘
Figure 2.14 is a diagram on p 125. It was not an extension of the previous methodology, but rather an amalgamation (they called it a ‘blend’) of multiple reports from different sources. The result is not directly comparable to the prior charts. Here is the text which is under the chart:
‘Figure 2.14:
Monthly Arctic sea-ice extent anomalies, 1973 to 2000,
relative to 1973 to 1996. The data are a blend of updated Walsh (Walsh,
1978), Goddard Space Flight Center satellite passive microwave
(Scanning Multichannel Microwave Radiometer (SMMR) and Special
Sensor Microwave/Imager (SSM/I)) derived data (Cavalieri
et al.,1997) and National Centers for Environmental Prediction satellite
passive microwave derived data (Grumbine, 1996). Updated digitised
ice data for the Great Lakes are also included (Assel, 1983)’
I recommend pulling down the TAR, and reviewing all the text in that section, as there are other important details contained in it which I do not mention.
What I will say, though, is that the discontinuity with the prior IPPC reports is not called out, but rather obfuscated by the way Figure 2.14 is described and shown. Nowhere in this section is the transition from 10 – to- 15% concentration mentioned explicitly. Rather, it gets glossed over with the comment about the ‘blending’ of the differing methods and satellites used. You have to go back to the referenced papers to understand from them the different aspects of how they were originally reported.
There are other issues, though. The first is that all the referenced papers used in the ‘blend’ were published in 1999 or earlier, but the chart goes out to the end of 2000, for a report published in 2001. To extend the chart, unpublished data had to be used, which is alluded to in the ‘updated’ aspect of some of the reports. This is one of the IPCC ‘no-nos’ which have been called out by others.
A second, IMO annoying issue is that the chart includes the non-sea ice areas of the Great Lakes. This completely obscures the relationship of the prior IPCC charts with the current one. As far as I can tell, this is the only IPCC report where this was done, and it was the last one which went back to 1973. However, with the Great Lakes included, the anomalies in the pre-1979 timeframe are now almost all positive, and nothing about the FAR and SAR lower pre-1979 anomalies is visible.
A funny oopsie… the vertical axis of the chart is labelled: Sea-Ice extent anomaly (10^2 x km^6), where the ^ indicates superscripted power. Ordinarily these charts use 10^6 x km^2 🙂
Though I am not quoting it, by AR4 (2005) the Arctic Sea Ice diagram begins with 1979… the shift of the ‘Satellite’ era is complete.
I hope this is what you were interested in.
I would add that Parkinson (1989) covers the years 1973-1987.
https://sci-hub.tw/10.1029/JC094iC10p14499
Thank you Stephen Fraser.
This clarifies the issue of sea ice data versions substantially.
I already have the IPCC reports which I use primarily to verify any claims made about it’s content. Your comments have piqued my interest however and I intend to read the section you referenced in TAR.
Thank you for taking the time.
In regards to Alaska, the Alaska Climate Research Center states:
http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.html
+42
Or (for temperature) in the Little Ice Age.
Sea ice and global warming
https://tambonthongchai.com/2018/08/04/does-global-warming-drive-changes-in-arctic-sea-ice/
https://tambonthongchai.com/2018/08/06/antarctic-sea-ice-1979-2018/
Nice post. Thanks for the clear explanation on area vs extent.
“… extent is always bigger …”
Not necessarily true.
If there are three cells each with 14% ice coverage, then:
– Area = 14% of total
– Extent = 0
Area also relies on a 15% threshold.
Oh, okay … thanks
Oh, okay … thanks
Which speaks volumes about the “science.”
>15% = 100%
<15% = 0%
It's almost like they make this schist up as they go along.
As someone pointed out, a shift in winds that pushes the ice up against the N. American or Asian shores could make a big impact on extent by increasing average density from 20% to 40%, without any change in total ice.
Note that NOAA Sea Ice Index applies that 15% threshold to a 16 km cell, so a flip upward means adding 16×16, or 625 km2 to the total. One reason I prefer MASIE is their use of 40% threshold on 4km cells.
Sorry for math mistake; SII uses 25 km cells, thus 625 km2 per cell.
The other day I mentioned that the difference (or even better) ratio of max vs min of the extent (or area) might be a good pointer of the medium to longer annual trend.
Hmm. link
For the last decade, the minimum ice extent has not followed the long term trend.
For the decades 1979-88, 1989-98, 1999-2008, the decadal trend is down in each case, at various slopes. For 2009-18, the trend is flat, with the last five years rising.
The trend for the next decade, 2019-2028 should be up. Plus the 30-year baseline will shift to 1991-2020, so more years will be in the normal range.
CB Thanks for the link.
If used as a metric for temp…..I think the min and max are probably the worst indications of a trend…extremes are too delicate.wind, currents….weather….affects them too much
Around May or Dec all the little lines come back together again………..that’s where a real trend will show up
Agreed for temperature. I use to track the CET daily min-max and I’m well aware of the issues involved
https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcSoZM4mBDU3OlJdlU5RvlF0ezVsV_F4nx34bytkFyCxbX8LyiUk
You can see the reason for alarm: linear trend 1992 to 2012 has zero ice in 2020.
I have objected for years to linear trend analysis for cycle-dominated processes. But I understand the reason they are done: when you say CO2 warming is linear, all outcomes must be linear, so that is what you look for. The conclusion determines the analysis.
The alarmists have a hammer. The world must be, therefore, built with nails.
Each time I see “acrtic sea ice” I toddle over to NSIDC and check the Sea Ice Extent and Sea Ice Concentration images, and SHAZAM, ice all over the Arctic Sea. Funny how that works. Ought to get Bill Clinton to explain what “ice free” means, he did a bang up job explaining what the meaning of “is” is.
I used to do that with Cryosphere Today – before it went down recently. The best bit about it was you could bring up side-by-side images for the Arctic ice cap for any two months over the entire satellite range. All you ever saw was a big phat ice cap waxing and waning with the seasons and a bit of variability superimposed. In no way was it ever possible to come away from there with a visual impression of any kind of Arctic ice “death spiral”.
Would love to get NSIDC to set up a paneled graphic showing multiple years of their Arctic Sea Ice images.
In the current conditions, there will ALWAYS be a winter sea-ice cap there, no matter if CO2 is 400 or 4000 ppm due to the configuration of oceans and continents (and an ice-cap on Antarctica). Unlike many previous epics that had no substantial ice.
Yes, if it’s dark for months at a time, ice will accumulate even on the equator.
We don’t really know for sure that the planet was ever ice free, except as it was forming. We only have a tentative idea that much of the surface was ice free, but we have only a vague idea of where the continents were at the time. It’s most likely that at the time of Pangaea, both poles were open ocean and certainly had seasonal ice caps and likely had permanent ice caps that we would never know about. The only things that would make this less likely, is if the Earth’s orbit was closer to the Sun or if the Sun was significantly brighter.
The bottom line is that given the current Sun, orbit and no other external sources of energy (for example, an impact event), Arctic and Antarctica is here to stay and no amount of CO2 will change this or could have changed this in the past.
True that we can’t ever be sure of these things. One point is that IMHO the atmospheric pressure was considerably higher in the early times (over VERY long periods the solar wind slowly eroded the atmosphere, even w/our magnetic field) and that acted as an additional greenhouse effect in the deep past.
What does Al Gore have to say about this? Why hasn’t he apologised for getting it so wrong?
David, might I suggest another measurement for Artic Ice? Sure Area and Extent are all scientificay, and satellite data is great. However I think a great measurement would be POTENTIAL FOR TRAPPING SHIP OF FOOLS. For personal entertainment purposes we could artifically lower the potential and trap a lot of SHIP OF FOOLS.
That’s a paradox!
PfTSoF increases as sea ice extend decreases!
You mean, a hull-crush or stranding metric? Woo-hoo.
I’m sorry, but the plural for ‘ship of fools’ is ‘ships of fools.’ Just like Attorneys General, Runs batted in, etc.
What are the dates of any satellite upgrades, replacements or recalibrations, if any, and do they influence the graphs?
Tom: One of the differences was with the new satellites at the end of the 1970s. The methodology for measurement changed from 10% to 15% concentration.
One difference in newer satellites is an NIR (near infrared) sensor which helps distinguish between clouds and ice, especially during polar winters. Older data often has ice misrepresented as clouds and/or clouds misrepresented as ice. At the poles, clouds tops can be warmer than the surface which makes them hard to distinguish.
MSN is running another “intrepid ice warriors” forced to abandon NW Passage, despite alarming ice melt story.
Yet, we find the first NW Passage occurred 102 years ago. This begs the question, why are contemporary passage attempts failing at alarmingly high rates in the face of reported record low extents?
Perhaps, we should be more alarmed by media’s willingness to prostitute itself to sell copy.
However the first passage took three years, and the second, about forty years later, took two years. For the last several years the NW Passage has been crossed regularly by yachts without need for reinforcement.
IPCC definition of ‘Nearly Ice Free’ is < 1 million sq km in September for 5 years in a row, which they predict is 'likely' under RCP8.5 (medium confidence) before mid-century.
… that is, in extent.
Nothing is “likely” under RCP8.5… It doesn’t even qualify as bad science fiction… 😉
Just passing on what was reported. Not advocating…
what they do is hype 1 million sq km like it’s gone….
That’s exactly the size of Egypt….Egypt is huge
Melting glaciers are a red herring. The math is absolutely clear on this.
The average ice coverage of the planet is about 12%. If all of this ice disappeared permanently, the reflectivity of 12% of the surface will drop from about 45% to 10%. The planet is 2/3 covered by clouds whose reflectivity is about the same as snow and ice so 2/3 of the 12% has no effect on the overall albedo, thus 4% of the surface has a net decrease in reflectivity of 35%.
The average solar input is 341 W/m^2. The polar regions where the ice is gets less than this, but will be ignored for now. The total new energy per W/m^2 across the planets surface becomes:
341 * 0.35 * .04 = 4.8 W/m^2
Doubling Co2 is claimed to be equivalent to about 3.7 W/m^2 of forcing and each W/m^2 of solar energy increases surface emissions by 1.6 W/m^2.
The total input power distributed across the surface becomes (3.7 + 4.8)*1.6 = 13.6 W/m^2.
Adding 13.6 W/m^2 to the current average surface emissions of 390 W/m^2 @ 288K becomes 403.6 W/m^2.
Convert 403.6 W/m^2 back into a temperature becomes, 290.5K which is only 2.5C warmer and this is after significant rounding in the direction of warming, as is common practice throughout consensus climate science.
If doubling CO2 caused all surface ice to be permanently melted, the decreased reflection combined with the increased atmospheric absorption will result in a global 2.5C temperature increase which is still not even enough to get to the nominal 3C claimed, much less enough to melt all that ice in the first place.
Of course, winter can’t be stopped and permanent ice will always be there.
The whole sea ice panic mongering story is nothing more than a microcosm of climate alarmism generally – start at a low (temperature) or high (sea ice extent) point, end at a warmer time with a higher (temperature) or lower (sea ice extent), declare a catastrophe.
Rinse and repeat (and repeat, and so on…).
Pretty much like the current political situation in America. Starting to see a pattern!
There is no ice it’s all gone Griff told me, next you will try and tell me the polar bears aren’t drowning.
Griff …. that’s a name I’ve not heard in a long time.
Yes, he’s using a different name now.
Global warning (Ode to Griff)
His name is Griffin. Folks though call him “Griff”
He hails from universities of stone
Debate with him is as a smoken spliff
It leaves one’s mental faculties undone
For high o’er land and sea and distant isles
The eye of Griff doth wander wide and free
All he beholds, his intellect defiles
Dreaming disaster from the rings of trees
The seas do rise – we’re told – to drown our coasts
Though photos of past bays show nary a change
Griff terrifies the kids with tales of ghosts
That steal the frost from every mountain range
Beholding life, he see-eth only death
In forms of beauty, veiled catastrophe
And morbid gas in every human breath
Damns sinners to a lost eternity
But that dread gas – O Griff! How see-est thou not
Bringeth not death but life, that springeth green
The photosynthesis thou hast forgot
Is nourished by the thing thou call’st unclean
And so adieu, my ode to Griff is done
To that sly master of the shifting files
Of numbers spelling our Armeggedon
And yet behind that mask of doom – he smiles!
Very nice!
The Arctic has warmed before.
Published in the Monthly Weather Review in October 1922:
As usual, the climate numpties try to claim that this was strictly a “local event”, and thus dismiss it.
Well at the same time as this happened the expedition to claim Wrangel island for the US was trapped by impenetrable ice for a couple of years leaving only one survivor. The claim of warming in the ‘arctic’ at that time is based on local data and never acknowledges what was happening on the Pacific side. Note that the ice-free ice in the region that report extends further north now and Wrangell is not hemmed in by ice.
What is never shown is the pre-1979 data, wheee the extent was much less.
That early Holocene High Arctic climate was less severe than now has long been known, as per this 1990 paper:
An Early Holocene Bowhead Whale (Buluena mysticetus) in Nansen Sound, Canadian Arctic Archipelago
http://pubs.aina.ucalgary.ca/arctic/Arctic43-1-50.pdf
The title didn’t copy correctly. Of course the generic name should be Balaena.
Under the new age/stage system for the Holocene, these whale remains are from the Northgrippian, middle of the three such intervals.
In a related news story, the government henceforth considers you bankrupt if you only have $1,000,000 or less in your bank account.
I am not sure if I cringe at the extent of your comment or the area which it covers.
I recently heard a bit of a lecture by Peter Wadhams who has a book called
“A Farewell to Ice.” It has all sorts of the alarmist talk. Has anyone here
at WUWT done a review of his work? Thanks.
https://wattsupwiththat.com/2016/10/09/whacky-peter-wadhams-doubles-down-on-the-sea-ice-crisis/
Simply extrapolating a 30-year trend indefinitely into the future is simply idiotic.
Thanks.
Even at the minimum satellite recorded sea ice extent northern Peary Land is still icebound.
The remains of a Dorset Culture umiak were found at an archaeological site at the entrance to Independence Fjord by Eigil Knuth in 1949.
http://pubs.aina.ucalgary.ca/arctic/Arctic5-1-17.pdf
I wonder what use a boat would have been to the Paleo-Eskimos who settled there?
More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.
Current warming and Arctic extent are NOT unprecedented.
Arctic sea ice’
The Iceberg that broke off in the Antarctic broke off because we have switched from ice melting to ice making. That means I believe we began the new Ice Age 18,000 years ago. The oceans at the time of the peak were at least 400’ lower than present. The ocean water around the poles is always turned over. I hope you know what that means.
The ocean at the edge of the ice berg, before it was an ice berg, was 400’ lower and it was the edge of the Continent, and the ice and snow were deep back to the center of the continent. The new snow, ice, began to grow, and the ocean began to rise. Because the ocean has turned over the upper level of the ocean is 32’F. Because the 39’F heavier water is a little bit lower, as the ocean rises it begins to melt the ice form the bottom and work its way inland. It has been doing this for the last 72,000 years. The ice and snow have been growing on the top, as the bottom is being eaten inward. The average iceberg is 80% underwater. After 18,000 years that which was over the land got over the water, got heavy enough and it broke off and floated way.
The Arctic ice at the north pole is doing the same. If you look at the Northwest passage, the shallowest is over land 400’ or less. The ice at the pole is an iceberg. As the ice and snow on top grows the iceberg gets heavier, and it sinks. The 39’F water works on the edge and the center gets thicker and the edge melts away, thus it looks like it is getting smaller but it is actually getting a lot thicker. The Antarctic ice core shows in the last 18,000 years the ice over land has risen 250 meters.
The term THE LAKE HAS TURNED OVER MEANS THE WATER AT THE SURFACE HAS REACHED 39’f. Water as it cools from 39’F to 32’F expands. As the surface water cools further. Thus the term the lake has turned over.
This is also the reason there is animal life on earth.
Its important to remember that the Arctic is mostly sea ice, as against the Antarctica which is mostly land ice.
Thus any weather event will move the sea ice around. commercially regarding shipping the Arctic has beeen Öpen”The late 1930 tees it was Öpen” and cer tainly many times in the past it must have been open.
The alarmests like it to be Öpen”, that proves to them that it must be getting warmer.
MJE
Michael.
On average, maximum Antarctic sea ice covers three million more square kilometers than does Arctic sea ice. However, at minimum Arctic averages over three million more sq km more sea ice area.
So, the Antarctic has a lot more land ice than the Arctic, but about the same sea ice extent over the course of a year. However the Antarctic also has more “land” ice grounded on the sea bed. Only during glacial intervals are there substantial ice shelves in the NH.
Middleton is such a funny fraud
Hey dave
The Chukchi Sea IS NOT THE ARCTIC !!!!
it is part of the arctic
of course your source McKay knew this.
here is the fraud dave middleton
“The Arctic was probably ice-free during summer for most of the Holocene up until about 1,000 years ago. McKay et al., 2008 demonstrated that the modern Arctic sea ice cover is anomalously high and the Arctic summer sea surface temperature is anomalously low relative to the rest of the Holocene.”
McKay did nothing of the sort.
Their claim was about the WESTERN ARCTIC and they even note that the EASTERN ARCTIC showed just the opposite
“The Holocene record from site HLY0501-05 illustrates
the sensitivity of hydrographical conditions in the western
Arctic Ocean. The data show a long-term warming that is
opposite to what is reconstructed for the eastern Arctic and
point to a bipolar behavior of the Arctic Ocean at the timescale
of the Holocene.”
but then you knew that and thought you could fool your readers.
Interesting though that you love proxy studies and draw a conclusion from a single one.
fake skeptic
Mosh…
Luv ya man… But look at the >50% sea ice months McKay has for “modern sea-ice cover.” It matches the 1979-2018 NSIDC average of 10.6 months.
Gosh David! It looks like you have gained an admirer. Me thinks he doth protest too much. However, you should be congratulated on getting him to do more than just lob a snowball as he drives by.
For Mosh, with apologies to my kinsman and the great American Gospel singers whom he studied:
https://en.wikipedia.org/wiki/Charles_Davis_Tillman
Give me that CACA religion,
Give me that CACA religion,
Give me that CACA religion,
It’s good enough for me!
It was bad for the Penn State chillun,
It was bad for the Penn State chillun,
It was bad for the Penn State chillun
It’s good enough for me!
It was good to profit Mikey Mann,
It was good to profit Mikey Mann,
It was good to profit Mikey Mann,
It’s good enough for me!
Maybe you’ll prefer Stranne et al., 2013…
Steven,
I’d urge you to look at all Holocene Arctic reconstructions rather then just snippets from one which you interpret to support your faith.
http://notrickszone.com/2018/04/26/arctic-temps-2-6c-warmer-than-today-with-4-5-fewer-months-of-sea-ice-coverage-2000-years-ago/
For instance please check out eastern Greenland:
de Vernal et al., 2013
“[W]hereas many core data show little difference between the 1953-2003 sea ice average and the late Holocene reconstruction, some cores are characterized by large differences (Fig. 4). In particular, the late Holocene data of the Chukchi Sea and the Nordic Seas off eastern Greenland, suggest much less sea ice than what was observed at the scale of the last decades. … At the Beaufort Sea sites, the variations are of limited amplitude and the estimates are close to “modern” observations, but all records show an increase of the sea ice cover over the last centuries. At the Chukchi site, the record shows large amplitude variations with a distinct trend for an increased sea ice cover towards modern values over the last centuries. … Particularly high export rates of sea ice through the East Greenland Current have been attributed to extreme AO/NAO synopses (e.g., Dickson et al., 2000; Vinje, 2001; Rigor et al., 2002). It is thus possible that the 1953-2003 mean sea ice extent along the east Greenland relates to an unusually strong positive NAO. … The early Holocene (9-6 ka) data suggest negative anomalies in the eastern Fram Strait (MSM712), the southern Labrador Sea (HU094), the Estuary of St. Lawrence (MD2220) and the northernmost Baffin Bay (HU008). These sites recording less sea ice and thus warmer conditions [than present] are all located in areas under the influence of North Atlantic waters.”
Or how about north Greenland:
https://www.researchgate.net/publication/252572926_Ice_free_Arctic_Ocean_an_Early_Holocene_analogue
Or this from 2014 for the Arctic Ocean generally:
Arctic Ocean perennial sea ice breakdown during the Early Holocene Insolation Maximum
https://www.sciencedirect.com/science/article/pii/S0277379113004162
Sorry, but only a fully indoctrinated, card-carrying arch druid of the CACA religion could deny that for most of the Holocene, most of the Arctic Ocean and adjacent seas was less icy than now.
The science is settled on that point. From every possible source of evidence.
Although of course, science is never really settled. There might have been some freak summers during the Holocene Climate Optimum in which Arctic sea ice looked like today’s frigid conditions.
Mosh just needs to look at what I cited from McKay et al., 2008 and how it compares to the overall Arctic. McKay’s cores are from the Chuckchi Sea. His “modern sea-ice cover” matches the NSIDC data for the entire Arctic… A pretty good indication that it’s reasonably representative of tha Arctic Ocean.
That said, I should have specified that McKay’s core samples were from the Chuckchi Sea, as I have every other time I cited it.
David.
Clicking on the link you posted shows that. But yes, might as well draw attention to that fact.
Obviously, not every part of the Arctic is always in perfect synch. There was less open water in the 1920s in some regions than others, but by the ’30s and ’40s, the whole Arctic looked much like now, for instance.
If we only had satellites in the 1930’s… better yet, since the Upper Pleistocene .
David,
Yes, a shame. And no ARGO floats, to boot. Nor well maintained land stations.
But even had we those instrumental advantages, adherents of the CACA religion would still adjust the data to serve their faith-based purposes.
Considering how accessible the Arctic has become, allegedly due to CAGW, our intrepid modern ‘sailors’ seem to spend an awful lot of their time puttering along behind ice-breakers that clear a path.
http://arcticnorthwestpassage.blogspot.com/2018/09/ccgs-henry-larsen-working-in-arctic.html?view=sidebar
My attention was recently drawn to this paper (published 24 Sep, so very new):
http://iopscience.iop.org/article/10.1088/1748-9326/aade56
which claims: