From the University of Calgary Utoday:
Melting Arctic ice cap at record low – By Heath McCoy
Think of a poor hamster on a spinning wheel, caught up by momentum and unable to stop until it’s overwhelmed, sent tumbling, crashing out of control inside.
That’s the analogy John Yackel, head of the department of geography, makes when he considers the annual summer ice melt in the Arctic, which he’s been closely monitoring for the past 15 years – documenting the ice cover as it’s steadily shrunk in the wake of Arctic and global warming.
Thoughts of imminent crashes seem particularly ominous this year as last week marked the unofficial peak, or the end of the summer ice melt, with ice levels more dramatically diminished than at any time since satellite monitoring began 33 years ago.
The previous record low for Arctic sea ice extent, set on Sept. 18, 2007 with a 4.17-million sq.-km. ice cap, was already shattered by the end of August this year when it had melted to below 4-million sq. km.
“This is the smallest minimum ice extent we’ve ever had, and not just in the satellite record, but probably in the last million years,” says Yackel, a sea ice geophysicist and climatologist.
From the patterns he has observed, this year’s extreme melt could be the beginning of a frightening trend.
Yackel and the university-based Cryosphere Climate Research Group use satellite technology to research the physical properties of Arctic ice. As recently as the 1980s, most of the ice in the Arctic Ocean was “multi-year ice,” – thick ice that would remain throughout the summer. At that time, the split between multi-year ice and seasonal ice – ice that would melt away in the summer – was about 80 per cent multi-year and 20 per cent seasonal.
“In the last 20 years we’ve almost gotten to the point where we’ve reversed that ratio,” Yackel says, predicting the ice extent that covers the Arctic Ocean “is likely to be gone in the summers within the next 20 to 25 years, if not sooner.”
The depleting ice cover would have serious ramifications for the planet. Arctic ice acts as a reflector of sunlight, helping regulate the Earth’s temperature, cooling the climate.
“When there’s no longer that sea ice below the air mass and it’s just open ocean, that’s when more moisture off the ocean’s surface gets into the atmosphere and the water vapor in the atmosphere makes for more violent storms,” says Yackel.
“We can also expect to see an increase in storm frequency and storm intensity for most of the world’s populated places as the Arctic and Earth continues to warm.”
David Ball cryptically opines: “Still refusing to understand, despite admissions that completely undermine your own position. Weird.”
I stand by what I said. Perhaps you you could enlighten us all as to what I said that you think shows some sort of willful misunderstanding.
http://www.nature.com/nature/journal/v479/n7374/full/nature10581.html
“Think of a poor hamster on a spinning wheel, caught up by momentum and unable to stop until it’s overwhelmed, sent tumbling, crashing out of control inside.”
“That’s the analogy John Yackel, head of the department of geography, makes when he considers the annual summer ice melt in the Arctic, …”
The science behind Yackel’s ice melt claim is as sound as his understanding of the momentum of the spinning wheel. Apparently as a Geography professor he never took freshman physics and has not a clue as to what causes the wheel to spin in the first place. The energy to keep the wheel spinning comes from the hamster due to friction unless a large mass in the form of a flywheel is added to the hamster’s wheel to provide momentum when the hamster stops pushing on the wheel. If it had such mass the poor hamster could never get the wheel spinning in the first place.
Thank you Steve, for that reconstruction of Arctic sea ice,, as that paper phrases its results. The 2nd graphic uses a 40 year smoothing?
What is the Antarctic sea ice reconstruction for that same period? We are, after all, looking at total earth reflectivity, NOT just the little 4 million km^2 Arctic beanie above 80 north latitude.
.
E.M.Smith says:
September 26, 2012 at 3:54 pm
If you look at the ‘net flux’ movie here:
http://www.earthobservatory.nasa.gov/GlobalMaps/view.php?d1=CERES_NETFLUX_M
you can see that there is always heat loss from the poles. Briefly at the warmest moment of the year at the north pole, the heat loss drops to about a net balance, but not a gain (it’s hard to tell in the pictures if it has a gain for a brief moment, but some areas away from the pole do have gain late in the season. At some point the gain where the sun is overhead must pass through near zero to zero to negative at the pole, so watching that line move back and forth is educational).
The whole notion of the “Poles Warming” is just broken. At most they can “lose heat more slowly” and “freeze less”. They are always heat radiators. Just as the Equatorial zone is always where the heat gain is most (modulo a seasonal wobble to each side).
So anyone who talks about ‘heat gain’ at the pole is already showing signs of serious defect of thinking… It never ‘gains heat’ and it never ‘warms’. It loses heat, and at various rates. The only question is how much the equatorial and temperate heat gain is lost on the way to the pole…
That “net flux” – regardless of its source or heritage – is wrong. Dead wrong.
(“Inbound Flux at 1 Meter Above Ground”, or (more likely) “Theoretical Solar Flux at Top Of Atmosphere” ? Perhaps. But “Net Flux”? No.)
They simply project a simple flux into the atmosphere at each month of the year. Adequate for illustration, BUT at March, northern hemisphere sea ice is at its highest point, but northern hemisphere Land Ice Extents are beginning to melt out and LAND albedo is increasing significantly as plants breakout their spring growth – beginning furthest south of course and proceeding north as fields and forest floors melt, turn dark with bare soil, then green with new growth. But these change are ignored in the theoretical NOAA/NASA images. In early April, sea ice is still near its peak, but very little land ice is present in most regions. Again, the albedo (absorbed radiation and re-radiated energy levels) is “assumed” unchanged.
In the southern hemisphere, the same problems exist — BUT in the south, the northernmost sea ice extents ARE very important in changing the sea’s ability to absorb solar energy in open water, or reflect solar energy in ice-covered water. The very LOW solar sun angles of the Arctic north are NOT present in the Antarctic Sea Ice extents between 60 south and 70 south.
Thus, changing Antarctic Sea Ice extents at 60 south ARE very important in August and September when the northern Arctic sea ice extents are at a minimum but absorb virtually no radiation, but ARE reflecting massive amount of solar energy from the southern hemisphere. But, true to their “theoretical” (or top of atmosphere assumptions) NASA plots August earth “net radiation” as equal north and south of the equator at equal latitudes and over equal parts of the world – land, sea, or ice. ALL have “equal net radiation” at every latitude and every season.
And THIS kind of gross error is how the climate “science” industry begins their Global Circulation Models?
Steve Mosher, if you disagree with any part of this, please show me those GCM model runs that have been “correct” in showing no warming for 15 consecutive years, and those that DO showing the correct net radiation in their output for each season, each month, and over today’s ice caps. You claim the CAGW model community have model results that show no warming over that kind of interval. Fine, print the models, and their results, the date of each run, and the number of times that a 15 year flat-line global temperature HAS been predicted by ANY computer simulation.
P. Solar says:
September 26, 2012 at 12:19 pm
I think you could have been both more patient and more polite. The guy did respond to your email, which I think is good-hearted. You didn’t have to pry stuff out of him with FOI requests, did you? When you get a response from a fellow like you did, you might try to be good-hearted yourself. Cultivate a relationship. Maybe it will take some time, but often both parties learn a lot.
Here’s something to pop into your discussion:
There is a difference in the albedo and heat-retaining properties of clouds that are made of water vapor versus clouds that are ice-particles. The vapor clouds are more common over areas that are ice-free, and increase the albedo. Often they may be little more than a fog bank, below a thousand feet, but they can reflect sunlight quite well. (I noticed the “North Pole Camera” showed a lot of fog last summer.) This would tend to suggest yet another negative feedback. Namely, the less ice the more fog, and the more reflected sunlight.
Just one more idea to throw into the mix.
dikranmarsupial said (September 26, 2012 at 2:53 am)
“…Roy, you are aware aren’t you that Arctic sea ice extent has been shrinking much *faster* than in the model projections (see e.g. http://www.realclimate.org/images/seaice10.jpg), in fact the current sea ice extent is below the lower limit of the credible interval of the ensemble. Sea ice extent is an example where the models (and climatologists) are obviously unduly optimistic…
Pretty chart, and seems to match the observations vs models for the ARCTIC.
Did RealClimate provide a link to the observations vs the models for the ANTARCTIC?
Or is that just an inconvenient truth, especially since the IPCC said in the AR4 SPM (on pg 15) “…Sea ice is projected to shrink in both the Arctic and Antarctic under all SRES scenarios. In some projections, arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century…” – while in the summary of chap 10 they stated “…Sea ice is projected to shrink in both the Arctic and Antarctic under all SRES scenarios. In some projections, arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century….”
Well, either way, if you look through Chapter 10 (figure 10.13) you can see they DID run models. Problem is, it doesn’t look like the projections are matching observations.
Not sure how to post pictures here, but here’s the link: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/fig/figure-10-13-l.png.
tjfolkerts says:
September 26, 2012 at 11:17 am
“But if you DO choose to to look at those, then the inescapable conclusion is that the last few years are NOT “normal”. Considering the minima does NOT give a “misleading impression” that the ice is declining, since looking at the maxima ALSO leads to the conclusion that the ice is declining. (And looking at the age and/or thickness of the ice strengthens the conclusion even more).”
This statement is based on the satellite data. No? Then you follow with bullet point statements that reveals your limited understanding of any other known quanta and admit the satellite era is too short.
“FWIW, I agree that ….
* 35 years is a relatively short time to study any climate phenomenon.
* using the last 35 years to define “normal” is definitely a bit arbitrary.
* Ice has most likely been lower “in the last million years” (quite possibly sometime 6-10,000 years ago).”
“Inescapable conclusion”, followed by “35 years to define normal is a ‘bit’ arbitrary”
Then the clincher light bulb going on, albeit dimly; “most likely been lower in the last million years”
Now do you see?
As the Earth’s surface is 70% water (around 361 sq Km), why is it so dramatic that the Arctic being ice free will make so much difference? The Arctic ice changes around 9M sq km so seems pretty small compared to the persistent, always evaporating, 350M sq Km remaining.
The average temperature difference between the ocean and the atmosphere is about 2C, and this small temperature difference drives ocean evaporation. In the Arctic winter, the temperature difference will be something like 10 times greater. So evaporation rates will be high, resulting in rapid ocean cooling.
Otherwise, he completely ignores a physical mechanism that will cause the rapid differential melt of older ice (insolation+black carbon), and completely ignores that we are seeing record rates of new ice formation over the winter.
The only hamster I see is one desperately spinning to get his next bag full of GW grant money.
I see that we are “talking past each other” a bit. There are two very different points that you seem to be trying to roll into one.
1) The ~ 35 years of satellite data is rather short from a climate perspective. Data before that is of much more limited quality. As such, this satellite data is insufficient by itself to establish long-term trends or variability. I have no problem acknowledging that when climate conditions were different 6,000-10,000 years ago (or during other interglacials), the ice conditions could also be quite different – with summer extents similar to (or even smaller than) now.
2) On the other hand, the data for the last 35 is indeed quite good — measurements of the extent and area are available in pretty darn good resolution on a nearly daily basis. Looking specifically at that set of very good data, it is clear that the extent is declining — whether we look at spring or summer or fall or winter. This is in contrast to the very different claim that P. Solar made:
First of all, it seems to be generally acknowledged that the winter extent will not drop as quickly as the summer extent — pretty much the entire Arctic will refreeze every winter, (albeit with thinner ice since there is less to start with) so the winter extent will only drop a bit around the edges.
That said, the maximum is NOT “almost back to the 30 year average”. The ice almost got back to the 30 yr avg for about one week this past year. Furthermore that week was NOT at the annul maximum — the annual maximum looks (eyeballing) to be about 0.3 – 0.4 million km below the 30 yr avg this past year. And the maximum has been below the 30 year average every single year for nearly a decade.
I don’t know what ‘ “catastrophic” melting’ means (such ‘scare’ words have little meaning or use), but I don’t see any “undeniable” end to anything in 2007. http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi_range_ice-ext.png The data is still low for any of the three measures. The “all year average” hasn’t improved since 2007 and I will pretty much guarantee that 2012 will set a new record low for the annual mean (along with the already-guaranteed record summer minimum). It looks like the melting is continuing and the extents keep declining.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So yes, I still stand by my conclusions:
* It IS “inescapable” that the ice has been declining significantly for 35 years and has been below average (for the satellite era) continuously for nearly a decade.
* It is NOT “undeniable” that this trend ended in 2007.
* None of this is contradicted by acknowledging that a) records were less good before 1978 or b) that ice extent may have been lower 9,000 years ago.
Now do you see what *I* am saying? Or would you agree with P. Solar that “it is undeniable that the “catastrophic” melting ended in 2007”?
Thanks for you reasoned comments.
tj says: First of all, it seems to be generally acknowledged that the winter extent will not drop as quickly as the summer extent
I have not disagreed (nor commented) on that assumption but that assumption should not be taken as a reason not to take note of the maximum. That seems to be the false conclusion that may imply from that. Perhaps because they are not interested in a metric that shows a less dramatic result.
http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi_range_ice-ext.png
The Norwegian plot does account for maximum as well, two points is better than one point per year, though each one point per year plot is very course we can clearly see an improvement since 2007 in their min-max average. This is what you incorrectly call “all year average”. It is not. It is the average of two days. That is exactly my point. I plot ALL the data and the effect is more visible. Yes, it is still notably lower that the 30y average, I’m not suggesting there has been a total recovery.
Cyrosphere Today uses all available data but the feature I pointed out is rather obscured by the short term fluctuations.
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.arctic.png
That is why I filtered it. I spotted something had changed but I could not clearly see what.
tj says: The ice almost got back to the 30 yr avg for about one week this past year.
Without arguing exactly what date it happened , the anomaly data got quite close to the 30y average in four out of the last five years, including this “worse than ever” year, which got closest.
I would agree with you to some extent.
that the ice has been declining significantly until 2007. I would go further and point out a clear, uninterrupted slide from 1995 – 2007.
It is that slide that has been interrupted. I find it difficult to see how anyone can refuse to see that feature clearly shown in my graph.
http://i48.tinypic.com/dzj70k.png
Caleb says:
September 26, 2012 at 5:57 pm
>.>
I think you could have been both more patient and more polite. The guy did respond to your email, which I think is good-hearted. You didn’t have to pry stuff out of him with FOI requests, did you? When you get a response from a fellow like you did, you might try to be good-hearted yourself. Cultivate a relationship. Maybe it will take some time, but often both parties learn a lot.
>>
More patient? I asked two direct questions twice. Asking a third time would badgering. He clearly does not wish to answer them.
He would not have looked too good if he just ignored my email. I did thank him for taking time to reply. FOI? Well I can’t FOI him for an admission he was making untenable claims can I ? I certainly did not get ANY reply to my two simple, direct questions after two attempts. That is clear evasion and refusal to address the issue. It is clear that I will not learn anything from someone like that.
He may have learnt something from the graph I sent him, though I doubt it.
For anyone still having problems seeing the change in behaviour since 2007 let’s look at the rate of change of ice extent with 365 day filter:
http://i47.tinypic.com/5l2olz.png
I think that clearly shows the pattern of continued and increasingly rapid ice loss from 1997-2007 has been broken. Current behaviour is very similar to that around 1992.
That is what I am drawing attention too. This is seen by looking at all the data and is not seen by focusing on the annual minimum.
Unfortunately the filter requires a couple of years of data ahead of it’s last point so it ends in 2010. I think it will likely continue to decline to this year, which corresponds to 1995 in the earlier pattern.
The evidence is that the pattern of “catastrophic” melting has ended. It remains to be seen whether the new mode of behaviour will continue to mimic the 1990s oscillation or not.
Does anyone know if the Antarctic sea ice has hit the yearly maximum yet? Looks like the anomaly is currently +1.145 million square kilometers, and it looks like we just hit a new maximum as of 9/26 and it still may be increasing. When is the “average” date of maximum for Southern Hemisphere sea ice, and what are the details of what is going on down there? Maybe Anthony could write something up on this (or someone else could contribute an article on this). I think we need to draw more attention to what is going on in the SH and give some real detailed analysis of it. I am especially concerned because I recently saw a paper stating that the LIA may have started in the Southern Hemisphere, and if that is indeed the case, we may see history repeating itself.
Comparing rate of change in ice extent to NH lower tropo temps:
http://i49.tinypic.com/2cfr09d.png
Here I’ve inverted the rate of change of temp (faster warming : faster melting) and shifted the UAH TLT data forward 9m ,which as a quick estimate seems to be the best match in the cycles.
This does not show air temps are necessarily driving the ice change, more likely it’s just because air responds quicker to whatever is driving all this than this ice and water does.
the interesting point is that this relation mostly broke down during the accelerating melting period and came back into synch around 2007. Again confirming a change in the pattern of climate and an end to the accelerating melting.
The pre-90s cycle, oscillating around 0.1 x 10^6 km2 / year melting seems to have been re-established in an almost identical form and level.
Now maybe someone who is getting paid a good salary to do climate research can work out what caused that change in pattern to break and then reform.
David A. Evans says:
September 26, 2012 at 12:13 pm
Where do you get the idea that because ice feels cold it is not a good insulator? It feels cold because it’s cold and has a high thermal mass, if it was not a good insulator it would feel as warm as the underlying water. Incidentally, the reason dry cardboard doesn’t feel as cold as ice is because its thermal mass is minute in comparison. (A bit like air really which is one reason why the whole AGW thing is a scam.) Strangely, the water under the ice is warmer and not exposed to allow either radiative or conductive energy loss. Do you want to revise that now?
Are you an arts major?
Dave E.
I agree it has a relatively high thermal mass (about ½ that of water), but it is also a poor insulator. In fact, your point about high thermal mass undermines your assertion about why it doesn’t feel warm even though there is warm water underneath. Materials with high thermal mass are rarely good insulators (such as concrete, cement, marble). Ice’s high thermal mass prevents the warmer water underneath from heating the ice to the same temperature because its thermal mass resists rapid temperature change, not because of insulation qualities. The specific heat of ice is 2, its U value is 2.18 W/mK, and so its R value is .4. Compare that to glass fiber with a specific heat of 1.4, U value of .04, R value of 25. Ice is a very poor insulator – it conducts 2.18/.04, or 50 times the heat of glass fiber.
Air’s thermal mass has little to nothing to do with AGW, it is not the thermal mass of the atmosphere that traps heat, it is the presence of greenhouse gases, without which the earth’s surface temperature would be -18C rather than the current 14C average.
Yes, water under the ice is warmer; I’m not sure why that is strange, it’s the air temperature that causes the water to freeze, not the water temperature. Radiative heat loss is of course still possible with ice as with water since both have nearly identical emissivity. Conductive or convective water to air heat losses have no bearing on global temperatures, since that involves heat just moving from one place to another – not out into space, as is the case with radiative heat flow. And in any case, you seem to be implying that open water conducting/convecting heat into the air near the surface is a good thing. In fact, it is not – it’s the temperature differential between Arctic air and lower latitude air that drives the jet stream. A smaller differential means a weaker jet stream, which in turn means more erratic weather.
While I do enjoy art, I have a bachelors and masters in electrical engineering, with 3 published, peer reviewed papers in IEEE journals.
Did you go to university?
Chris
P Solar says: “I find it difficult to see how anyone can refuse to see that feature clearly shown in my graph. http://i48.tinypic.com/dzj70k.png”
That graph does seem to show a “pause” — but I would caution against reading too much into brief changes. And if you continue plotting the data, you will see that the “recovery” you claim to clearly see is an illusion — a brief fluctuation in the statistical noise.
I took the daily area data from University of Illinois and plotted it up through the most recent data point (which I think is the end of Aug, 2012, but I am not sure off-hand). (You can see the graph here: https://sites.google.com/site/sciencestatsandstuff/global-warming/miscellaneous-comments/has-arctic-sea-ice-started-to-recover). The lowest point in the 2 year moving average is the last data point in the series! Yes, the past two years are the lowest two years in the data. That does not sound like a recovery to me! The last 1 year is close to the record, also not an indication of “recovery”.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I *do* think there is an interesting shift in the pattern starting in 2007, with much wider annual swings becoming the norm. The winters are trending down only slowly, but the summers are trending down quickly. Just what this portends for the future is tough to predict.
Cool, we’re talking the same language at last.
I did plot all the data but the gaussian being a better filter needs a broader window. One reason I prefer this filter is that it has a clean frequency response with no stopband leakage. This is the opposite to runny means which let huge amounts of what you think you filtered out get through. This can have quite perverse effects at times and is hard to predict.
Most people who use runny means don’t even understand what all this means and are quite unaware of the problem or its effects.
In simple terms it can mean the filtered result can get bent left and right and peaks can even get inverted. This is generally unhelpful and can be quite misleading.
You will notice that the last graph I linked here, I also put in the shorted 180d gaussian. This is too short a period to remove most of the annual variation I did this precisely to get some idea where the data was headed since I am aware the last couple of years are downwards.
I think the longer filter (when there’s more data) will then be down to the bottom of the cycle as it was in 1995. IF that pattern holds, I would expect to see an upturn for about 3 years.
Thanks for the link to the ice area data , I was wanting some area data to compare to. I’ll run it through similar gaussian filter and see if there is any notable difference. I don’t like relying on just one data source with this stuff.
Chris says:
September 27, 2012 at 10:52 am
The ice in the arctic is in a sandwich. Most of the time it is covered with varying depths of snow of varying density and hence varying thermal properties with fresh, uncompacted snow as the best insulator. The insulating properties of snow are in the same range as most insulating materials used in construction.
Your whole argument about the insulating properties of ice is, therefore, somewhat irrelevant. It only applies when the ice is not covered by snow which I believe to be a very small proportion of the time in the polar regions.
Here is a comparison of the Cryosphere Today ice area data you used and the NOAA ice extent.
http://i49.tinypic.com/xn9jqv.png
Since everyone is taking about climate _change_ I continue to concentrate on looking directly at change rather then trying to infer it by eye from the time series data.
The two series are not measuring the same quantity so the differences are not too surprising , the similarity is notable.
I was doubtful of the early down swing in ice extent until I found I matches a similar swing in UAH lower tropo. That boosted my confidence in both. That air temp bears more relation to the thinner and more dispersed ice in the >15% cover category is unsurprising.
The ice area data shows a recent cycle that appears to have a mean around -0.08e6 km2/year, whereas around 1985 was pretty neutral over a cycle. In contrast, the current ice extent cycle is a little lower than ice area but is on a par with it’s 1990s cycle.
Both series show an end to the continual and accelerating melting and a return to earlier cyclic behaviour, though a small, long term underlying decline is still present in ice area data.
The recovery period was short lived in both series but was there. I never hear that reported. The last 5 year cycle has been notably better then 2000-2005 when the average was nearer 0.15e6 km2/year.
That seems to be firm indication from both datasets that the rate melting is easing off rather than getting worse. That is quite different from conclusions that are drawn by focalising in the annual minima. Hence my initial point that we should be using all the available data not just one day per year.
For anyone intending to stick around on Earth for a while, that has to be rather better news than what we usually get fed.
Thanks to TJ for productive debate and providing the link to ice area data. Having the two different metric provides more confidence in the result and provided some interesting differences.
Now can we talk about sine wave like oscillations of periods like 60 years, which help to clarify why the 35 year satellite era warming is not so scary. i.e. no tipping point other than a swing back the other way.
Billy Liar says:
September 27, 2012 at 1:53 pm
Your whole argument about the insulating properties of ice is, therefore, somewhat irrelevant. It only applies when the ice is not covered by snow which I believe to be a very small proportion of the time in the polar regions.
Actually, I was replying to another person’s post. Thomas U stated:
Has he ever considered the insulating capabilities of ice, perhaps thought of designing one of these wonderful and ever so accurate climate models which includes the reduced insulation?
Thus, I commented about ice and not ice+snow. I agree that snow has good insulative properties compared to ice. It is not as good as construction materials – snow at .18 is about 1/3 fibreglass batts at .55-.76 (for 1 inch of material), but still of course much better than ice. But since there is much less multiyear ice, by definition there will be a smaller portion of the Arctic that has insulative cover during the year, which in turn means more convective heating of the air, which in turn means a weaker driver of the jet stream, not to mention reduced cooling capacity to cool down the latitudes during the summer months.
OMG, I’m embarrassed to be from Calgary. This guy has given clowns a bad name, he’s another gravy sucking embarrassment to all scientists.
Chris says:
September 27, 2012 at 10:52 am
David A. Evans says:
September 26, 2012 at 12:13 pm
Where do you get the idea that because ice feels cold it is not a good insulator? It feels cold because it’s cold and has a high thermal mass, if it was not a good insulator it would feel as warm as the underlying water. Incidentally, the reason dry cardboard doesn’t feel as cold as ice is because its thermal mass is minute in comparison. (A bit like air really which is one reason why the whole AGW thing is a scam.) Strangely, the water under the ice is warmer and not exposed to allow either radiative or conductive energy loss. Do you want to revise that now?
Are you an arts major?
Dave E
This is an attempt to baffle with bullshit. Does the surface radiate at the same level as the underlying Arctic water?
Fine except that the main band is… 15µm what sub zero temperature is that?
It’s not at all strange, never said it was, happy you admit that as you’ll find out.
No argument there
Except of course, they aren’t at the same temperature. Has the Kelvin scale escaped your notice?
WOW! I would say moving energy from the lower troposphere to the upper troposphere and possibly beyond may make a difference.
Now you’re just making shit up.
No I didn’t, but I did get royally pissed off with people who did, then got promoted above me after I taught them everything they knew.
One job I had, I interviewed several people with BScs, only one came up to scratch.
Hope I got it right this time. 😉
DaveE.
David A Evans says: “Where do you get the idea that because ice feels cold it is not a good insulator? It feels cold because it’s cold and has a high thermal mass … “
Actually, when dealing with the sensations of “cold”, insulation IS more important than thermal mass! The temperature you “feel” is determined by how quickly heat is conducted to/from your skin. Aluminum at 10 C will “feel” much colder than wood at 10 C, even though the thermal mass (ie specific heat) is higher for the wood. The higher thermal conductivity is what makes it feel colder. On the other hand, a block of aluminum at 10 C will melt ice cubes much faster than a block of wood at 10 C, again because the thermal conductivity is higher for the Al (despite the wood having a higher specific heat).
RECAP: Aluminum feels colder than wood precisely because Al is a poor conductor, despite the fact that wood has a higher thermal mass.
Do *you* want to revise *your* conclusions now?
“Fine except that the main band is… 15µm what sub zero temperature is that?”
This is another common misconception — that only some specific temperature is associated with some particular wavelength. This often comes from a misconception of Wien’s Law.
* If you want a blackbody that emits better at 15 um than at any other wavelength, that blackbody would have a temperature of
(2.9 ×10^−3 m·K) / (1.4 x 10^-5) = 193 K
However, blackbodies above and below this temperature ALSO emit at this wavelength. In fact, any blackbody warmer than 193 K will emit MORE 15 um radiation than the 193 K object did!
Furthermore, CO2 ALSO radiates/absorbs at other wavelengths. Certainly these are relatively small parts of the thermal IR spectrum, but only small changes are needed to make “small” (1 K) changes in global temperature.