By Andy May
Northern Hemisphere sea ice area is an important climatic indicator because it determines how much of the Arctic Ocean and surrounding seas are open to the atmosphere. Ice is a good insulator and traps heat in the water below it (Peixoto & Oort, 1992, p. 361). Ice is also a good reflector of sunlight (high albedo), whereas water is a good absorber (low albedo). While we have no accurate data on Northern Hemisphere sea ice area (called NH_ice here) before 1978, the first year of good satellite data, it does appear to follow the global 60-70-year global climate oscillation (Wyatt, 2020). This may be because the closely related AMO affects the sea ice area as it warms and cools, of course the reverse could also be true.
Prior to 1978 we have reports on ice extent, which is weakly related to sea ice area, from ship observations. Sea ice extent was very low in the early 20th century warm period from about 1920 to 1945, this was also within the early 20th century rise in the AMO, which is analogous to the AMO rise that began in 1977, see here and here. Ship observations frequently mention an ice-free Arctic Ocean from the 1850s through the 1870s, another time of a warming AMO. Silas Bent proposed that the Atlantic Gulf Stream met the warm Pacific Kuroshio current in the Arctic and kept it ice free in 1872 as shown in figure 1 (Luedtke, 2015).
Systematic observations of Arctic ice did not begin until 1885 when the Danish Meteorological Institute (DMI) began to systematically make maps of ice extent using reports from “explorers, whalers, and other navigators of the polar seas.” These reports were published in both Danish and English (Luedtke, 2015). However, by then the AMO was entering a negative state.
By the mid-thirties, during the early 20th century warm period, which was also a prominent AMO warm period, the Arctic Northeast Passage was unusually open for ordinary steamships (Luedtke, 2015). This part of the Arctic Ocean, around Svalbard, Novaya Zemlya, and Franz Josef Land (see figure 2) is usually closed by ice most of the year.
While the Northeast Passage was open most of the early 1930s, the Northwest Passage, Beaufort and Bering Seas remained ice covered over most of the year. The loss of ice in the Arctic during the 1930s prompted some to warn the world about potentially dangerous climate change (Manley, 1944), but as the world cooled over the next few decades worries about global warming diminished until temperatures began to warm again in the 1980s.
Polar energy fluxes vary by season as shown in figure 3. In summer, outgoing energy to outer space is small because the incoming energy (meridional transport + solar) goes into melting ice and snow and warming the Arctic Ocean. In winter this sequence reverses, there is very little incoming solar energy, and the summer meltwater refreezes which frees the latent heat stored in the water. Thus, most of the energy transport to outer space occurs during the winter months.
During winter the radiative energy loss at the top of the polar atmosphere is very large. About two-thirds of the loss is balanced by the inflow of transported energy from lower latitudes and one-third through or from the surface. The heat released from the surface seems to come about equally from lowering the ocean temperature and from the freezing of surface waters. Both processes are largely a function of Northern Hemisphere sea ice area or NH_ice.
Most energy delivered to the Arctic from the lower latitudes is via storms or “transient eddies” (Barry, Craig, & Thuburn, 2002), but some is from the mean meridional circulation (Kaspi & Schneider, 2013). The energy flux between the atmosphere and the surface in the Arctic is characterized by a large upward transport of energy from the surface during the winter. Water temperature below the ice is no lower than –1.9°C, while the atmosphere can be –30 to –60°C. Sea ice is a very good insulator, but when the ice is thin or absent there is some loss (Peixoto & Oort, 1992, p. 361).
NH_ice probably changes on a periodic basis because the arrow in figure 1 labeled “Meridional Transport in” and/or solar input vary. When the AMO or global temperature are warming (for example from 1975 to 2000, see here or post 1) it can also mean that the Arctic Oscillation is mostly positive and the winter polar vortex is strong. This climatic configuration keeps cold air in the Arctic, and it cools as a result. Since cold air is trapped in the Arctic, the middle latitudes and the Northern Hemisphere, except for the Arctic, are warmer.
All the factors in creating the conditions for high or low NH_ice are not known, but the so-called “Warm Arctic-cold continents” and its opposite the “Cold Arctic-warm continents” oscillation is well known (Overland, Wood, & Wang, 2011). This pattern is related to both the Arctic Oscillation (AO) as discussed above and the North Atlantic Oscillation (NAO). It is even possible that the Warm Arctic-cold continents oscillation is influenced from as far away as Antarctica through the Southern Annular Mode (SAM) (Lin, Yu, & Hall, 2025). I just mention all this to show that all the climate oscillations interact with one another and how it all fits together is very complex and poorly understood. We see the results, the climate oscillations themselves, but we do not know how they work, and they cannot be properly modeled.
Figure 4 shows the longer-term full-year HadCRUT5 and AMO rising, as NH_ice falls from 1987 to 2024. The very sudden rise in the NH_ice from 1984 to 1987 precedes a strengthening of the Polar Vortex, which begins in 1987, just as the sea ice begins a long decline. Before 1997, NH_ice changes precede AO changes, but after 1997 this relationship reverses, the reason for this change is unclear. Nothing is simple.
The long decline in winter NH_ice from 1987 is mirrored in the Schwabe 11-year solar cycle peaks as shown in figure 5, which is a bit counterintuitive. As solar activity increases after a solar cycle low there is usually an NH_ice peak with a zero to one-year lag. Likewise, as solar activity decreases after a solar cycle high there is an NH_ice low with a one to two-year lag.
Discussion
The Arctic is a major net emitter of radiation during the winter. The combination of little to no solar input, a frozen surface, nearly cloud free skies, and very low humidity mean that almost all surface and atmospheric radiation emissions go to space. As figure 3 shows, two-thirds of the energy entering the Arctic in the winter months is brought in by atmospheric meridional transport and most of that is brought in by storms.
The Arctic Oscillation is positive when the Polar Vortex is strong and negative when it is weak. Thus, we expect NH_ice to increase when the AO is positive and decrease when it is negative, but this relationship is not consistent and often reverses as seen in figure 4. There must be other factors that affect ice cover. I have no explanation for why ice cover decreases when the Sun is less active.
We would expect NH_ice to increase as the sun gets weaker and to decrease when it is stronger, especially in the Arctic, but the opposite has occurred. The Arctic is covered with an ocean and ocean water has a low albedo and is a very strong absorber of solar radiation.
There is no obvious explanation for the relationship between all these factors, but we only have 47 years of good NH_ice data, which is not nearly enough. The overall global climate cycle is 60-70-years as noted in post 1, and maybe when we have that much data the answer will become clear. This is not a very satisfying post, since I can present all the information I could find on NH_ice, and still have no answers as to why things are as they are. All I can say is we see definite patterns, but the patterns cannot be modeled or explained. As I wrote in post 1, “Most of the natural ocean and atmospheric circulation oscillations examined in this post are not modeled properly (some say not modeled at all) in current global climate models.”
So given all of that, let’s imagine a comment like the following from a member of the “consensus:”
Andy,
You are a complete idiot. The Sun isn’t responsible for the NH_ice decline and neither are the other oscillations, it must be increasing CO2 that is responsible! We get there by process of elimination. What else could it be?
To which I reply:
The CMIP6 and earlier sets of climate models assume that CO2 is responsible for warming and the ice decline, yet they cannot reproduce the critical NAO, AO, AMO, SAM, and PDO oscillations. They do better with ENSO but still have major problems with it (IPCC, 2021, pp. 489-514). It is unclear that the models adequately reproduce any of the observed long-term climate oscillations. I should add they are not weather models, but climate models, and as such they should reproduce these oscillations if they are accurate. They have a CO2 bias, yet they do not reproduce them. Process of elimination is not enough to make your case.
Works Cited
Barry, L., Craig, G., & Thuburn, J. (2002). Poleward heat transport by the atmospheric heat engine. Nature, 415, 774-777. doi:10.1038/415774a
IPCC. (2021). Climate Change 2021: The Physical Science Basis. In V. Masson-Delmotte, P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, . . . B. Zhou (Ed.)., WG1. Retrieved from https://www.ipcc.ch/report/ar6/wg1/
Kaspi, Y., & Schneider, T. (2013). The Role of Stationary Eddies in Shaping Midlatitude Storm Tracks. Journal of the Atmospheric Sciences, 70(8), 2596 – 2613. doi:10.1175/JAS-D-12-082.1
Lin, H., Yu, B., & Hall, N. (2025). Link of the Warm Arctic Cold Eurasian pattern to the Southern Annular Mode variability. npj Climate & Atmospheric Science, 8. doi:10.1038/s41612-025-01102-z
Luedtke, B. (2015). An ice-free Arctic Ocean: history, science, and scepticism. Polar record, 51, 130-139. doi:10.1017/S0032247413000636
Manley, G. (1944). Some recent contributions to the study of climatic change. Q.J.R. Meteorol. Soc., 70, 197-219. doi:10.1002/qj.49707030508
Overland, J. E., Wood, K. R., & Wang, M. (2011). Warm Arctic—cold continents: climate impacts of the newly open Arctic Sea. Polar Research,, 30(1). doi:10.3402/polar.v30i0.15787
Peixoto, J., & Oort, A. (1992). Physics of Climate. New York: Springer-Verlag. Retrieved from https://www.amazon.com/Physics-Climate-Jose-P-Peixoto/dp/0883187124/ref=sr_1_2?crid=3BCKX8A3FIUUH&keywords=Physics+of+Climate%2C+Peixoto&qid=1649270821&sprefix=physics+of+climate%2C+peixoto%2Caps%2C100&sr=8-2
Wyatt, M. (2020). Circulation Patterns: Atmospheric and Oceanic. In Y. Wang, The Handbook of Natural Resources, volume VI (2nd ed., Vol. 6). CRC Press. Retrieved from https://www.taylorfrancis.com/chapters/edit/10.1201/9780429440984-9/circulation-patterns-atmospheric-oceanic-marcia-glaze-wyatt
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Is “El Niño” & “La Niña” included in that group of five oscillations?
You may paint me ignorant.
I’ve always said the IPCC can’t predict el El Niño & La Niña.
I’d like to find out if it’s way worse that that.
The El Niño & La Niña events are part of the ENSO oscillation. AR6 discusses it in the pages referenced in the post. Specifically in section 3.7.3, pages 495-499. They do a little better with ENSO than the other oscillations, but not all that well. In the attached figure from AR6, observations are the black lines, the model results are in color. Unlike the other oscillations the models generally follow the trend of the ENSO cycle, but very poorly.
Here is another analysis of oscillations from AR6. The black dots on the Taylor plots are the observations. The modeled NAM results are completely separated from the observations, NAO and SAM are fairly close, but still pretty far away on average.
Thanks
Parkinson’s work covering 1973 to 1987 has value but is discounted and ignored.
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/JC094iC10p14499
From its abstract:
The northern hemisphere overall shows no significant trend over the 1973–1987 period, although over the ESMR years (1973–1976) there was an upward trend and over the 8 full SMMR years (1979–1986) there was a lesser downward trend. The record as a whole gives no definitive indication from the varying sea ice extents of any consistent warming or cooling of the north polar region.
Thanks! Great reference.
Andy,
The only idiot among the two of you in the communication is the one who believes he’s knowledgeable of ALL of the sources of climate variability.
It took a reread, but I see what you are addressing and I agree.
Andy, despite years of watching the waxing and waning of ice extents, my paradigm was subconsciously wrong, and others may share the same misconception.
I owe my enlightenment to a great book by Russian scientists from the Arctic and Antarctic Research Institute (AARI) in St. Petersburg. It’s entitled Climate Change in Eurasian Arctic Shelf Areas, by Ivan Frolov et al. The ebook is behind a paywall, but Dr. Bernaerts graciously provided me a hard copy from his library.
It’s Not an Ice Cap, It’s an Ice Blender
Frolov et al made me realize that all our observations of Arctic ice are in fact snapshots of an ice blender constantly moving ice around the Arctic ocean. When we observe and measure extent in one of the seas, that particular ice was not there previously, and will be gone in the near future, replaced to some extent by ice coming from elsewhere. That is the full implication of Arctic ice lacking a land anchor (like Greenland or Antarctica) and existing as “drift ice”.
Frolov et al. provide the statistics regarding the annual dynamics. In the wintertime the shelf seas form “fast ice”, that is ice locked onto the coastlines. Additional ice has nowhere to go but go with the flow north toward the pole or to the neighboring sea. In the summer the flow reverses and the Arctic basin, which received ice from the marginal seas, now sends ice back to replace losses there.
It is a mistake to think of the Arctic as an ice cap that shrinks and grows in extent. In fact Arctic sea ice is constantly in flux, more like a kalidiscope than an solid sheet. And the natural forces within the climate system cause fluctuations on a quasi-60yr oscillation.
My synopsis is:
https://rclutz.com/2016/03/02/the-great-arctic-ice-exchange/
Very useful info, thanks Ron. I agree, I don’t think sea ice extent is very useful from climate studies, only sea ice area is useful.
Also ice volume which according to Piomas is currently very low.
Andy, “only” is too strong. Both Ice Area and Ice extent require a cell to be at least 15% ice covered. Area estimates involve mutiplying the cell total by the exact % of ice concentration above 15%. That precision is not always achievable from satellite sensors, especially during melt season.
“Extent measurements can compensate by simply including every grid cell with 15 percent or more sea ice concentration in the extent total. Getting the extent figure right does not require precisely measuring the sea ice concentration of every grid cell. Instead, it just means identifying the grid cells that meet the threshold.”
“Relying on extent rather than area has other advantages. There is greater agreement among sea ice experts across institutions about sea ice extent than there is about sea ice area. In addition, simply counting the grid cells that meet the threshold, which includes most grid cells within the sea ice perimeter, reduces day-to-day variability in sea ice numbers.”
https://nsidc.org/learn/ask-scientist/what-difference-between-sea-ice-area-and-extent#anchor-why-use-extent-instead-of-area-
My husband was on an ice breaker in the Beaufort Sea in the mid 80’s. Its job was to clear the moving ice pack ahead of an exploratory oil drill ship. Every so often the ice pack would move so fast that the drill ship had to up anchor and reposition itself when conditions improved. Impressive technology until the gov shut it all down.
Water is a good absorber of sunlight, when the sun is directly overhead. As tAbove the sun moves away from the vertical, less energy is absorbed. As the sun approaches the horizontal, almost all of the energy is reflected.
In Arctic regions, where one tends to find sea ice, the sun is always close to the horizon, even in the summer.
Above the arctic circle, the sun doesn’t even get above the horizon for parts of the year.
Finally, pristine ice is good reflector of sunlight. As the ice ages, it gets a covering of soot and dust, which increases the amount of sunlight that it absorbs.
For much, perhaps even most of the Arctic, the difference in the amount of sunlight reflected from ice vs. water, is not significant.
I disagree. In the summer, a considerable amount of sunlight is absorbed in the Arctic meltwater pools and in the open ocean as well documented in Peixoto & Oort. Take a closer look at figure 3. The difference is huge. The reflectivity off of ice and snow does vary with the age, but it is always much larger than water, even at low angles.
MarkW, the assessment you presented includes an unidentified assumption that the surfaces, both ice and water are smooth. When waves are added, the angle of incidence for sunlight into water increases the effective orthogonal (decreased angle of incidence) surface area that is much greater than a calm sea.
Waves are ,fascinating but make exact or even good electro magnetic optical depth and reflection calculations impossible.
Ice has the equivalent of terrain effects (ridges and valleys). Were not for those, an EM calculation on the skin depth of ice and reflections would be akin to rough concrete or brick. Perhaps desert sand would be a better equivalency.
One of the biggest deficits of all of the climate models is they basically ignore EM fields and waves theory and applications. Solar radiation is EM fields and waves.
I don’t see CLOUD COVER thrown in. Cloud cover is both a reflective heat shield and an insulating blanket.
Like nearly all of us, I don’t understand cloud cover, it is a huge factor and has an unknown impact. In winter there is very little cloud cover over the Arctic, but in the summer there are lots of clouds and haze. I’m sure it matters, but I don’t know how much. Lots of interesting research on cloud impacts going on now, I’m trying to follow it.
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Lots of factors besides cloud cover including the Moon.
IPCC TAR Chapter 14 Page771 pdf3
The climate system is a coupled non-linear chaotic system,
and therefore the long-term prediction of future climate states
is not possible.
Long time ago Kip Hansen put up a video of nine double pendulums
to illustrate what that looks like. It WAS on the You Tube but it’s gone.
Here’s one somebody made earlier !!
https://www.youtube.com/shorts/JTqEjL-5YOc
Nice post, AM. I qualitatively tackled the oscillatory complexities of Arctic sea ice in essay Northwest Passage in ebook Blowing Smoke.
Your illustrated point about the climate model results being completely off from observations is to the great chagrin of ‘climate experts’ like Wadhams, who confidently predicted the Arctic would be summer sea ice free by about a decade ago.
Everybody should get a copy of Rud’s ‘Blowing Smoke.’ Many insights to ponder.
DMI also posts ice thickness https://ocean.dmi.dk/arctic/icethickness/thk.uk.php which is at a very low value this season.
Thanks for the article Andy. A good read.
“When the AMO or global temperature are warming (for example from 1975 to 2000, see here or post 1) it can also mean that the Arctic Oscillation is mostly positive and the winter polar vortex is strong. This climatic configuration keeps cold air in the Arctic, and it cools as a result. Since cold air is trapped in the Arctic, the middle latitudes and the Northern Hemisphere, except for the Arctic, are warmer.”
No the Arctic is warmer when the AMO is warmer, and the warm AMO is driven by negative North Atlantic Oscillation regimes, but you won’t see that by looking at winter only NAO/AO. It is a huge mistake to look at winter only AO/NAO, the largest loss of sea ice is during deeply negative NAO summers, like 2007 and 2012. Major warm pulses to the AMO peaking in August following El Nino episodes also contribute though a negative influence on the NAO.
I contend that weekly-monthly NAO anomalies are indirectly solar driven, and it happens to be chance that the solar forcing was higher during a high proportion of the winters. But with the NAO data for all months, the negative regimes 1995-1995 and 2005-2012 driving the warmer AMO are obvious.
Ulric, You write:
See attached plot and see if the Arctic ice follows either the AMO, NAO, or AO. I don’t see it, especially since 1995. The NAO and AO do seem to match the ice from ~1988-1995, but not before or after.
Since 1995, the NAO, AMO and AO sort of track one another. The ice has a mind of its own. All values are full-year values. I prefer winter values because that is when everything happens. Not much happens in the summer months, which follow a different drummer as pointed out in the post.
Again, using winter only NAO makes it look like positive NAO is associated with a warmer AMO, when the reverse is true, negative NAO drives a warmer AMO. Negative NAO reduces sea ice much more in summer than it can in winter.
I don’t see that large gain in winter sea ice in the late 1980’s in this chart, the September minimum follows the warming of the AMO.
https://www.environmentalgraphiti.org/all-series/artic-sea-ice-extent-1979-2017
The plot at your link is sea ice extent, not sea ice area. Sea ice extent can be very misleading.
The NAO in my plot above is for the whole year, it is not a winter NAO, so I’m not sure what you are getting at. The sea ice area anomaly I plotted is the full year value. This plot is not winter values. The data I used is NOAA data from here:
https://psl.noaa.gov/data/timeseries/month/NHICE/
The site has both extent and area, but I used the area data.
I am not convinced, that looks like Jan-Feb-Mar NAO.
The sea ice is almost identical to your figure 4, which you labeled winter sea ice. The roughly 10% of decline is about right for winter sea ice.
A warm AMO is definitely negative NAO driven, that’s why the AMO is always warmer during centennial lows in solar activity.
You are making no sense. NAO is not plotted in figure 4 and you have not plotted sea ice extent or area. Your comment has no relevance to this discussion. Rephrase.
The difference between area and extent trends, a nothing burger:
Here is the NOAA area and extent. Notice the dramatic different from 1985 to 1988. Your plot also shows differences from 2005-2013. Data from here:
https://psl.noaa.gov/data/timeseries/month/NHICE/
“You are making no sense. NAO is not plotted in figure 4 and you have not plotted sea ice extent or area. Your comment has no relevance to this discussion.”
You plotted the NAO in your first reply in this comment thread, pay attention please.
I compared what you have called ‘NH sea ice area yearly’ in the plot in your first reply chart above, to what you have called ‘NH winter sea ice area’ in Figure 4.
The Copernicus plot has both area and extent, but splitting hairs about their differences only now serves as a distraction from my primary arguments which you are ignoring.
To be fair, to claim that positive AO is associated with a warmer AMO, is the greatest error that one could possibly make in climate system dynamics.
Lets start again…
“When the AMO or global temperature are warming (for example from 1975 to 2000, see here or post 1) it can also mean that the Arctic Oscillation is mostly positive and the winter polar vortex is strong. This climatic configuration keeps cold air in the Arctic, and it cools as a result. Since cold air is trapped in the Arctic, the middle latitudes and the Northern Hemisphere, except for the Arctic, are warmer.”
Nonsense, the Arctic is warmer when the AMO is warmer.
“Nonsense, the Arctic is warmer when the AMO is warmer.”
The data clearly shows this is not the case from 1992 to 2024.
Try showing Arctic temperatures and the AMO series!
Here we go again, every time you lose an argument you change the subject! My post and comments never mention Arctic air temperatures. Give it up man, you can’t lose that then change the subject forever. Write your own post, I’m not going to research Arctic air temperature for a post on a dead thread.
You have lost several arguments in this exchange, and you have now lost your temper too, I have not lost any.
Here is what you said:
“it can also mean that the Arctic Oscillation is mostly positive and the winter polar vortex is strong. This climatic configuration keeps cold air in the Arctic”
Get that? Arctic air, so you lost that argument too.
Claiming that the Arctic is colder when the AMO is warmer is not only irrational, it is bizarre given that we know that the Arctic warmed 1925-1945 with the AMO warming, and that the Arctic warmed again from 1995 with the next AMO warming.
You seem to have been swayed by the idea that positive AO is associated with a warm AMO phase, when it is clearly negative NAO episodes and regimes which drive a warmer AMO. At inter-annual and at inter-decadal scales.
If positive AO was driving a warmer AMO, the AMO would be colder instead of warmer during centennial solar minima. That’s a serious issue to get backwards.
“We would expect NH_ice to increase as the sun gets weaker and to decrease when it is stronger”
Weaker solar activity means negative NAO, which warms the AMO and the Arctic, which are always both warmer during centennial lows in solar activity. But the indirect solar forcing of the NAO does not follow sunspot cycles. Major lows in the solar wind occurred at sunspot maximums in 1969 and 1979-80, and then the major major lows shifted to just after sunspot minimum from the 1990’s.
The phase shifts between the NAO and sunspot cycles have been noted by Jason Box with Greenland temperatures, and an old paper correlating UK temperatures with sunspot cycles.
AMO anomalies are always the coldest near sunspot minimum during a cold AMO phase (major highs in the solar wind driving positive NAO regimes), and never the coldest around sunspot minimum during a warm AMO phase. That is why in 2013 I predicted a renewed warming of the AMO after 2014, and a new cold blob from 2025.
https://www.woodfortrees.org/graph/esrl-amo/from:1880/mean:13/plot/sidc-ssn/from:1880/normalise
solar wind temperature and pressure:
I’d like to read Andy’s view on the SH polar vortex because it’s effects on movement of air mass, ozone and NOx concentrations, and temperature are much stronger and more proloned than the NH due to the difference and proximity of land (topography). The NH vortex is often broken up – almost into two but more like a figure8. The SH however is largely just ocean and the vortex develops into a tight ring – a durable inverted icecream cone-like barrier. Nullschool earth shows this. Erl Happ wrote about his observations here and posted on WUWT many times a decade ago.
https://reality348.wordpress.com/
I will discuss SAM (the Southern Annular Mode) which is very related to the southern Polar Vortex, in Climate Oscillations #5, immediately after #4 on LOD. The list of posts, in order, is in Table 1 here:
https://andymaypetrophysicist.com/2025/06/16/climate-oscillations-1-the-regression/
Thanks.
“Silas Bent proposed that the Atlantic Gulf Stream met the warm Pacific Kuroshio current in the Arctic and kept it ice free in 1872 as shown in figure 1″
However despite what Mr Bent proposed he was wrong. The key word in Fig. 1 is “supposed”, i.e. the claim was not based on any evidence whatsoever. Again if you read the cited reference it is very clear that this was a belief and not a fact. Actually reading all of Luedtke’s article would be useful. To quote from its conclusion
“Numerous scholars contend that climate change scepticism derives from a few prestigious, non-specialist scientists. Their work has shown how this small group of men attacked the scientific research of others, misrepresented that scientific data, and hid the inconsistencies of their
own scientific work in order to stall state regulation of human activity thereby protecting both industry interests as well as their own ideological convictions …
recurring visions of an iceless polar sea prompt sceptics to infer that sea ice extent fluctuates
cyclically. … This way of thinking, however, usually relies on isolating specific moments in the ice-free Arctic Ocean narrative. … Such decontextualisation of individual episodes exaggerates incidents of historic sea ice loss and gain, thereby flattening the long-term downtrend. Instead of
seeing a ‘reduction in Arctic ice cover [that] started in the late 19th century, consistent with the rapidly warming climate, and became very pronounced over the last three decades’, sceptics fashion a sort of pulse line with regular deviations from an otherwise constant standard (Polyak
and others 2010: 1757). This enables them to read natural variability whereas a majority of scientists now acknowledge that ‘Many observed changes in . . . sea ice extent . . . over the 20th century are distinct from internal variability and consistent with the expected response to
anthropogenic forcing’ ”
Which seems to describe extremely accurately what is Dr. May is doing here.
Hilarious, you take exactly what I said in the post and somehow twist it into a insult. Shameful. You clearly deserve the down arrows.
Very nice Andy.
One of my other interests came up with this map of the WW2 Arctic Covoys. Not exactly precise but interesting.
“What else could it be?”
The Conan Doyle/Sherlock Holmes error “When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.”
Not true at all, ir just means you don’t know everything, as it runs counter to Occam’s razor in that it’s not got fewest assumptions
At first I thought your post was addressed to Andy.
I reread and you are addressing the hypothetical post made by the consensus:
We get there by process of elimination. What else could it be?
An interesting post.
One nit, “all which is impossible” implies there is no lack of knowledge, data, evidence, etc.
That aside, your point is logical.
How can anyone be sure everything is known?
It can only be assumed that all is known.
In essence, Occam’s razor states that the simplest explanation for a phenomenon is likely to be the most accurate one.
“of two competing theories, the simpler explanation of an entity is to be preferred”
Occam’s Razor does not result in the truth, but rather the explanation that is more likely to be true.
When one achieves an insight, the logical question is, “What else could it be?”
If a politician says that, he is trying to convince the audience he knows the “truth.”
When a scientist asks that, he is soliciting review and critique.
When an engineer asks that question, he is seeking an analysis of alternatives.