One of the interesting things about being a scientist is seeing how unexpected observations can galvanize the community into looking at a problem in a different way than before. A good example of this is the unexpectedly low Arctic sea ice minimum in 2007 and the near-repeat in 2008. What was unexpected was not the long term decline of summer ice (this has long been a robust prediction), but the size of 2007 and 2008 decreases which were much larger than any model had hinted at. This model-data mismatch raises a number of obvious questions – were the data reliable? are the models missing some key physics? is the comparison being done appropriately? – and some less obvious ones – to what extent is the summer sea ice minimum even predictable? what is the role of pre-conditioning from the previous year vs. the stochastic nature of the weather patterns in any particular summer?
The concentration of polar expertise on the last couple of questions has increased enormously in the last couple of years, and the summer minimum of 2009 will be a good test of some of the ideas that are being discussed. The point is that whether 2009 is or is not a record-setting or near-record setting minimum, the science behind what happens is going to be a lot more interesting than the September headline.
In the wake of the 2007 minimum, a lot of energy went in to discussing what this meant for 2008. Had the Arctic moved into a different regime where such minima would become normal or was this an outlier caused by exceptional weather patterns? Actually this is a bit of false dichotomy since they aren’t exclusive. Exceptional patterns of winds are always going to be the proximate cause of any extreme ice extent, but the regime provides a background upon which those patterns act. For instance, in the paper by Nghiem et al, they showed the influence of wind patterns in moving a lot of thick ice out of the Arctic in early 2007, but also showed that similar patterns had not had the same impact in other years with higher background amounts of ice.
This ‘background’ influence implies that there might indeed be the possibility of forecasting the sea ice minimum a few months ahead of time. And anytime there is the potential to make and test predictions in seasonal forecasting, scientists usually jump at the chance. So it proved for 2008.
Some forecasting efforts were organised through the SEARCH group of polar researchers, and I am aware of at least two informal betting pools that were set up. Another group of forecasts can be found from the Arctic ice forecasting center at the University of Colorado. I personally don’t think that the intrinsic worth of a successful prediction of overall sea ice extent or area is that societally relevant – interest in open shipping lanes that might be commercially important need much more fine-grained information for instance – but I think the predictions are interesting for improving understanding of Arctic processes themselves (and hopefully that improved understanding will eventually feed into the models and provide better tests and targets for their simulations).
What was particularly interesting about last years forecasts was the vast range of forecasting strategies. Some were just expert guestimates, some people used linear regression on past data, some were simply based on persistence, or persistence of the trend. In more mature forecasting endeavours, the methods tend to be more clustered around one or two proven strategies, but in this case the background work is still underway.
Estimates made in June 2008 for the September minimum extent showed a wide range – from around 2.9 to 5.6 M km2. One of the lowest estimates assumed that the key criteria was the survivability of first year ice. If one took that to be a fixed percentage based on past behaviour, then because there was so much first year ice around in early 2008, the minimum would be very low (see also Drobot et al, 2008). This turned out not to be a great approach – much more first year ice survived than was predicted by this method. The key difference was the much greater amount of first year ice there was near the pole. Some of the higher values assumed a simple reversion to trend (i.e. extrapolation forward from the long-term trend to 2008).
Only a couple of the forecasts used physics-based models to make the prediction (for instance, Zhang et al, 2008). This is somewhat surprising until one realises how much work is needed to do this properly. You need real time data to initialise the models, you need to do multiple realisations to average over any sensitivity to the weather, and even then you might not get a range of values that was tight enough to provide useful information.
So how did people do? The actual 2008 September minimum was 4.7 M km2, which was close to the median of the June forecasts (4.4 M km2) – and remember that the 2007 minimum was 4.3 M km2. However, the spread was quite wide. The best estimates used both numerical models and statistical predictors (for instance the amount of ice thicker than 1m). But have these approaches matured this time around?
In this year’s June outlook, there is significantly more clustering around the median, and a smaller spread (3.2 to 5.0 M km2) than last year. As with last year, the lowest forecast is based on a low survivability criteria for first year ice and I expect that this (as with last year) will not pan out – things have changed too much for previous decades’ statistical fits on this metric to be applicable. However, the group with the low forecast have put in a ‘less aggressive’ forecast (4.7 M km2) which is right at the median. That would be equal to last year’s minimum, but not a new record. It would still be well below the sea ice trend expected by the IPCC AR4 models (Stroeve et al, 2008).
There is an obvious excitement related to how this will pan out, but it’s important that the thrill of getting a prediction right doesn’t translate into actually wanting the situation to get worse. Arctic ice cover is not just a number, but rather a metric of a profound and disruptive change in an important ecosystem and element of the climate. While it doesn’t look at all likely, the best outcome would be for all the estimates to be too low.
BobFJ 22 Jul 2009 at 8:48 pm
I’m dull, I still don’t get the joke about geologists. Maybe because I’ve been overexposed to ’em? Father, grandfather, two brothers-in-law, the list goes on, it’s positively stony here.
“For a wordsmith like you, I’m rather surprised that you distort my “[NOT] significantly accelerate this normal process” to mean an assertion that I’ve claimed there is no effect from warming.”
Words matter. I don’t want to become all neurotic about semantics, but to me and the dictionary the qualifier “significant” is a verbal dividing line between things we may ignore and things we can’t. Something is insignificant if it does not matter, or signify. It’s significant if it has appreciable impact, on measurements, hazards, whatever.
If you agree that a warming climate will have a significant, appreciable and important impact on the failure of ice shelves, then we don’t have a disagreement.
If you believe that a warming climate will have no significant, appreciable or important effect on ice shelves, we disagree.
“I’ve also written that as yet, there has been nothing produced here, claiming a significant effect from warming on these mechanical failures, that is any less speculative than my offering. (as far as I can see)”
Here is your original remark, and raypierre’s reply to you:
“May I point out that this phenomena and also the calving of icebergs are fundamentally mechanical fracturing failures. If you study the canyons developing in ice shelves, before break-up, they appear to run parallel to the influence of the ocean, primarily because of tidal and wave action, resulting in hinging at the sites of the canyons. As an engineer, I find it hard to see any climate change effect that would significantly accelerate this normal process. Changed wind strength or circulation? Increased melt within the canyons? Maybe…. but I doubt it.
[Response: Actually, temperature increase has been shown to have a very pronounced effect on the breakup of ice shelves. It is indeed mechanical fracture that does the job, but what warming does is to form massive melt ponds at the surface, which then cause hydraulic fracture. –raypierre]”
Your assumption is that raypierre’s response was speculation? Think for just a moment: would raypierre just make that up, especially given the level of scrutiny proprietors of this site endure? Not likely, huh? Yet you immediately generated and then propagated a hypothesis about ice shelves being essentially self-healing due to their thermal mass. You’ve stubbornly continued asserting that, not bothering to look up the literature, not bothering to do the maths to prove or disprove your hypothesis. Yet the burden is on -you- to do the work, because you are the person hypothesizing a challenge to what raypierre explained to you as being the accepted understanding of the system under discussion.
I absolutely agree with you about the benefits of a cross-disciplinary approach. That is why I’m highly confident that anthropogenic global warming is a problem of sufficient significance and probability that we cannot afford to waste energy in idle speculation about whether or not ice melts when warmed. Multiple scientific disciplines are producing research results that have a clear trend or signal telling us the climate is being mutated in a way that is undesirable, by us.
“…my formative tertiary education as an engineer included 5 years of study in “strength of materials” Call me a liar if you like, but that is hardly promoting sensible debate.”
I’d be engaging in baseless speculation if I called you a liar about describing your profession or training, which I did not. What I suggested was that your understanding was less than complete, but I doubt that, really, and my jab was unnecessary and counterproductive. That remark was prompted by the mixture of modes you’ve spun up with what I’m still going to call “handwaving”.
Hank Roberts Reur 219; your final para:
You gave such a profound philosophy, it is almost worth a gilt frame:
1) Maybe you are unaware, but the debate here has been geological. It has nothing to do with climate change, which is not a matter of dispute. It is about whether the accepted warming has a significant accelerating effect on what are fundamentally mechanical failures in ice shelves.
2) No! I do not have any geologist in mind for this consideration. (and BTW my “rock-engineer” was bit of a quip)
3) Do you think that cross-disciplinary science debates are bad for science?
I recommend that you study the following from the USGC (U.S. Geological Survey), with an open mind:
http://earthshots.usgs.gov/Filchner/Filchner
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BTW, you do not appear to have shown an interest in my earlier geological comparison:
Please refer to the following image of the Ross ice shelf, and you may notice that it terminates abruptly from mechanical shearing
http://www.eoearth.org/upload/thumb/1/10/Ross_edge_large.gif/250px-Ross_edge_large.gif
It is interesting to compare with the White Cliffs of Dover….. Got it?
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/White_cliffs_of_dover_09_2004.jpg/350px-
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Doug Bostrom, please note that the Filchner-Ronne Ice Shelf is much larger than Wilkins and Larson, (that have had so much attention recently). Of one of the three huge calvings, over two decades ago, this was written:
A24 was about 90 km by 95 km in area and about 400 m thick. (~1320 Feet). Did you see that: 400 metres thick? How does that compare with your concern about hypothesised weakening in an implied 30-year reduction from 228 to 220 metres in the recent events?
You might also find this interesting:
“…German scientists have recently learned that the Filchner-Ronne Ice Shelf is two-layered… …but the bottom 80 m of ice came from the water below. (BTW; sea water freezes at about 2C colder than fresh!)
BobFJ 22 Jul 2009 at 8:48 pm:
Whoops, forgot this!
“However, it also provides a reference to comment more on your simplistic hypothesis of comparing an ice shelf (plate) floating in complexly heaving water, to that of a beam with a reducing section-modulus.”
Yes, highly simplified, to match your equally simple but in a different sense opinion that you could not see how climate change could “significantly” accelerate the progress of failure mechanisms in ice shelves. The example I chose was the most direct and easy route to help you understand how wrong you are in making your assertion.
I see by your sudden fit of unaccustomed exertion in using the literature that you see my point and have been motivated to try and show how, right now, it’s not a big factor. Obviously, the reduction in competence of the structure when treated as a simple beam (sure, plate is a better descriptor for the structures we’re talking about) is going to depend on the magnitude of reduction in dimensions. Warming will lead to a reduction in those dimensions, ultimately a lot. You concede that a mechanism for significant acceleration is available. Thank you!
By the way, since you’ve re-discovered the literature, why not delve a little further, where you’ll discover references to the hydrofracture mechanism raypierre mentioned, temperature profiles of ice shelves showing how your refreezing conjecture is incorrect, descriptions of how sudden collapse of ices shelves are driven by a combination of “simple” peripheral plate failure leading to loss of compression thus increased opportunity for growth of meltwater driven fractures, etc. Why not keep going deeper?
BobFJ #245: “lowered” != “thinned”.
Freeboard is only 10% of thickness. So, more like 300 m -> 220 m over 30 years, accepting your other assumptions.
I like to follow the sea-ice situation on http://ice-map.appspot.com/ with daily mid-resolution satellite maps. Since a few days the ice is progressively cracking into smaller pieces and became a playing field for the weather conditions. The overall direction of the multi year ice is towards the warmer Atlantic and into Narres Strait.
Re: #246
Thanks so much for that submitted paper, Brian. Hope the authors don’t mind us having a look. I certainly appreciate looking at it.
Tenney Naumer at #240 wrote: “due to the radically changed albedo, the cold air that used to hang around up at the North Pole will get shoved out of the way, and the jet stream will go all wacky, and weather all over the Northern Hemisphere will change in ways we cannot even imagine, the changing patterns of wind will alter the sea-surface temperatures of the North Atlantic and North Pacific Oceans, also screwing with what we used to know as the four seasons. Everything we used to know will be useless. And, this will all probably take place within the next 5 to 10 years.”
This, along with the point you noted about melting tundra, is pretty much what I thought, but since I’m not in the field, I wanted to hear it from someone a bit closer to the data and models.
To Brian Dodge at #246–thanks very much. This looks like just the kind of article I was looking for. Perhaps we can move the discussion here more toward this article and away from lunar influence and placing bets on melt amounts?
#247 Me bad.. The ice is covering less area than last year, I miss wrote… Despite a huge cloud cover, implying heat in the Ocean air system beyond what is understood.
Speaking of errors, Ice models failing extent predictions perhaps have three different flaws:
1- Failure to calculate IR down welling, current with now a days cloud cover melts.
2-Not taking into account IR down welling from thin ice…
3- Not calculating the effects of less salinity due to multi-year sea ice or extra glacial ice melts.
Sea Ice climate model failure topic is in dire need of exploration…
#247, Wayne–
An eye-popping temp for Iqaluit! (Tomorrow’s forecast, 22/14 C; climate normals 12/4.) And sampling around the region, not that exceptional spatially.
Looking at the weekly forecast numbers, not too many days/locations are forecast to get down to the normal climatology.
It’s also interesting to see that the daily minimums that appear to be more elevated with reference to the normal than do the maximums.
No wonder the melt continues apace.
#259, Yet Kevin, cloud cover is the big story, #255, great link, hard to see the clouds, try
http://www.weatheroffice.gc.ca/satellite/animateweb_e.html?imagetype=satellite&imagename=hrpt_dfo_ir_m_………………jpg&nbimages=1&clf=1
this animation shows how bad it is, but surface temperatures are way up there. Expect rapid disintegrations just about now.
Of course its IR upwelling from thinner ice during any season which fascinates, yet I wonder if the models take that into account. I suspect a significant feedback
loop during extensive cloudy periods, playing an important role in tandem with cloud reflecting IR downwards, is IR in ice models well factored??…
Wow ….. SST’s becoming more and more red world wide as well. Not only in the Pacific.
http://www.osdpd.noaa.gov/PSB/EPS/SST/climo&hot.html
> ice shelves
BobFJ, you post huge blocks of words about what you believe but dont’ have time to read the abstracts, so you’re just talking about your opinion. If you’d at least read the last decade or so of abstracts, which are easy to find — heck, if you’d just read the Google excerpts on the search results page — it’d save you making a lot of statements about what should be that don’t match what’s in the literature. Another example of papers you’d find informative, pick a few from the recent ones here. This is the sort of work Ray pointed out in a reply days ago, which Doug reminded you about recently:
http://scholar.google.com/scholar?q=climate+%22ice+shelf%22+%22loose+tooth%22+fracture
#260 Here are the clouds and dark red melting areas using other bands (w/ infrared)
http://ice-map.appspot.com/?map=Arc&sat=367
Wayne, 260 & 26–
Wow, indeed. Remarkable to see so much of the Northern ocean with anomalies of +5 C. I must admit, though, that I don’t really have the contextual knowledge to profit much from the animation of cloud cover, though it was interesting to watch.
Re my 250–and pace wili at 259!–the IJIS revision of yesterday’s extent was indeed downward, so 2009’s IJIS sea-ice extent stands as the second-lowest ever for this date. There is the element of a spectator sport here, but I’m also hoping that it is unambiguously clear going into the Copenhagen conference that there is no question of an Arctic ice “recovery,” which was being touted earlier this year.
Sadly, I’m afraid that the Orwellian thought processes of some will still continue as in the past. After all, the record or near-record low we are about to witness will predictably be followed by a very rapid growth of new sea-ice over all the exposed open water, and this will be touted as a miraculous “recovery.” (Never mind if the freeze is two weeks later than it used to be.)
BobFJ 23 Jul 2009 at 1:00 am
“Doug Bostrom, please note that the Filchner-Ronne Ice Shelf is much larger than Wilkins and Larson, (that have had so much attention recently). Of one of the three huge calvings, over two decades ago, this was written:
A24 was about 90 km by 95 km in area and about 400 m thick. (~1320 Feet). Did you see that: 400 metres thick? How does that compare with your concern about hypothesised weakening in an implied 30-year reduction from 228 to 220 metres in the recent events?”
Yes, and thank you! That helps to illustrate something I believe you’re missing here.
Ice shelves can be thought of as structures for purposes of understanding their strengths and weaknesses. If you look at the literature, you’ll see many of the same techniques used in assessing the properties of engineered human artifacts are used in predicting and explaining how ice shelves behave.
However, ice shelves are -not- engineered. They take on a shape and size and set of behaviors dictated by outside, changeable and by us frangible factors. Their physical characteristics do not arise from choices made by a person working with a slide rule and specific set of performance objectives in mind. The mechanisms that dictate the gross physical characteristics of an ice shelf are composite and include a plethora of circumstantial features, each of those features being a reflection of the ice shelf’s environment and having in common only that they are phenomena that include water in its liquid and solid phases.
Especially, ice shelves are not overengineered. They are not constructed with the objective of having reserve strength. An ice shelf is a reflection of the instantaneous environment it is occupying. It is a structure that is constantly approximating an equilibrium state with its various external conditions. An ice shelf is as big as it can be at any given time, and the dictation of that size is external to the ice shelf.
In the case you cited, something in the environment controlling bulk behavior characteristics forced the Filchner-Ronne ice shelf to make a major adjustment. The external variance was small, indeed not easy to discern. Yet we see from the literature that what appear to be small adjustments to a change in external conditions of an ice shelf via a particular physical characteristic can result in significant changes in the gross characteristics of the ice shelf. This includes complete disappearance if a feedback mode is entered, such as is apparently occasionally the case when unloading of the confining forces partally controlling interior portions of a shelf occurs due to what at a glance appears to be an insignificant increase in calving,
BobF, try these references on ice shelf stability:
1) Rignot & Jacobs 2002 Rapid Bottom Melting Widespread near Antarctic Ice Sheet Grounding Lines (pdf)
…It is therefore not the average ice shelf melt rate, but the melt rate near the grounding line that will have the greatest impact on ice flow dynamics. As the properties and circulation of the ocean are modified by climate change, a corresponding change in the rate of basal melting in this region may alter ice thickness and motion enough to influence ice shelf stability.
2) Rignot & Kanagaratnam 2006 Changes in the Velocity Structure of the Greenland Ice Sheet Sci
3) Schoof 2007 Ice sheet grounding line dynamics: Steady states, stability, and hysteresis”
…The purpose of this paper is to develop an improved theory for marine ice sheet dynamics based on the physics of the ice sheet-ice shelf transition zone. Our work builds on a substantial literature which has identified coupling between ice sheet and ice shelves as an essential control on the dynamics of marine ice sheets.
That should at least partially answer your questions about how global warming is expected to lead to increased ice sheet volume loss.
P.S. BobF, No responses on the Petr Chylek et al. discussion? For more on that source, see the following:
Chylek et al 2007 “Limits on climate sensitivity derived from recent satellite and surface observations.”
We find that the climate sensitivity is reduced by at least a factor of 2 when direct and indirect effects of decreasing aerosols are included, compared to the case where the radiative forcing is ascribed only to increases in atmospheric concentrations of carbon dioxide.
That’s a straw man argument, since no one claims that the observed radiative forcing is due only to CO2. Look at the IPCC FAR report FAQ 2.1 figure 2 which shows a radiative forcing due to CO2 of about +1.6 W/m2, and a total aerosol effect of about -1.2 W/m2. Methane, N2O and other IR-absorbing gases account for another +1.0 W/m2.
In a separate effort, they based their ’empirical climate sensitivity’ estimate of 1.6C on the past ten years of data alone, not on the entire 20th century record.
They also tried to back this low sensitivity estimate up using historical paleoclimate data in a separate paper, which provoked this response:
Hargreaves & Annan, Comment on “Aerosol radiative forcing and climate sensitivity deduced from the Last Glacial Maximum to Holocene transition”
…However, their results depend critically on their selection of single unrepresentative data points from time series which exhibit a large amount of short-term variability, and are highly unstable with respect to other arbitrarily selected data points. When temporal averages are used in accordance with accepted norms within the paleoclimate community, the results obtained are entirely unremarkable and in line with previous analyses.
Taken together, this all seems to fit a pattern of selection of data from a variety of different fields for the purpose of promoting a pet theory. See Douglass & Knox for similarly discredited efforts to produce low climate sensitivity estimates using volcanic eruption responses, as debunked by Robock 2005, etc.
Keep in mind, as usual, that a single number for climate sensitivity does not really capture the complete climatic effects of doubling atmospheric CO2, one of which will be permafrost melting and the ‘natural’ injection of an uncertain further amount of CO2 and CH4 into the atmosphere, an example of a positive feedback which will then increase warming past the 2X CO2 level.
Tenny (240), et al: I might have missed it in earlier posts, but I don’t understand 1) what determines if an albedo change is “radical” — it seems the average of everything above the Arctic circle is short of radical; 2) why the change in albedo, even if near radical, has such a massive disruptive change in the atmosphere of the entire Northern hemisphere. What is the energy exchange that brings this about?
#264, Kevin, Exactly why we have to get ready for the “onslaught of the ill informed”, studying weather conditions every day helps, on the animation, try to see if something does not move, that is land or sea. I recommend Roger Pielke to try that before he even thinks about making another dumb statement about sea ice. But it is certain, they will claim a recovery, from 2007, even without comparing the weather conditions of 2007. I strongly believe that 2008-2009 is at par or worse than 2006-2007 because of cloud scenarios. But then again, asking for contrarians to study climate, as integrated long term weather, is asking too much.
So I warn them, in advance, we are ready for your comments, and have nothing but answers which will baffle and never be amusing but for those who study hard.
The pay for some is not money, but knowledge.
Continuing #240 Tenney Naumer and his game of what if…
In regards of the North Pacific, the Bering strait isn’t that deep it could host a massive cold surge, no doubt the jet stream will go erratic in the summer (unless it will be located round Greenland), not so in the winter, at the same time the usual patterns of low and high pressure areas are going erratic, and there’s no knowing what the rainiest or hottest month each year will be (there will be a strain on the agriculture), possible is the starts of winters will get more snow that melts during winter, this leads to earlier start to growing season, which may be interrupted by cold surge during the breakup of the wintry (stable) jetstream conditions… the transition to a new climatic stable state (resembling Miocene) is not rapid (due Greenland), so the erratic behavior of spring, summer and autumn weather may last for very long, and what the methane releases will do is out of my comprehension…
The Arctic freeze/thaw cycle is the pump that drives the global oceanic conveyor belt. As the cold sea water freezes, it concentrates salts in the unfrozen water, increasing it’s density. The heavier brine sinks and flows toward the equator. Dissolved carbon dioxide, calcium carbonate, and carbonate ions are part of the mixture that sinks to the bottom. The cold sea water of the Arctic is a strong sequester of carbon dioxide. When sea ice forms it covers the water which then can no longer absorb carbon dioxide. Conversely, when it thaws, absorption resumes. The rate of absorption decreases with increases in arctic sea surface temperature. The observed year to year increase in measured atmospheric carbon dioxide is very likely the result of increases in Arctic SST. The year to year decreases in sea ice is evidence the sea surface temperatures have been rising in the Arctic. A set of Bering Sea buoy data confirms this fact. These are natural processes that are not related to the rate of burning fossil fuels.
The rate of freeze/thaw is a fairly good measure of the net energy flux in and out of the Arctic. When it is dark, there is no solar influx. What little influx there may be is delivered by ocean currents and wind. During the time of the midnight sun, solar influx is at its maximum. Radiation out to space occurs day and night. The driving force is the difference between the surface of the earth and outer space to the fourth power. Exposed Arctic ocean is warmer than frozen sea ice and outbound flux from water is greater than from ice. Because thermal conductivity of ice is less than radiant transfer, ice serves as an insulator for the arctic ocean and thus slows the rate of global cooling. Heat must conduct through the ice before it can be radiated to space.
OT but here’s a thought provoking article on failure to communicate effectively as well as how we construct hopeful myths about many things including climate change:
http://www.newscientist.com/article/mg20327185.900-comment-why-people-dont-act-on-climate-change.html
I think the author too lightly dismisses the potentially powerful effect of a relatively small amount of money carefully spent on fostering misunderstanding. Yet it does seem undeniable that even those of us who are concerned about this problem are very ready to talk about it, less able or willing to act.
For a specific response, don’t forget that by making some adjustments at home that will save you money without any capital input, you can also substantially offset whatever transportation transgressions you may be guilty of committing.
Apologies for off-topic question, but do you RC folks expect to be commenting on:
I understand that at least two of the authors (de Freitas and Carter) are long-time denialists associated with oil industry funded denialist groups, and this study is being aggressively touted on the web as “refuting” the “hypothesis” of CO2-caused warming.
[Response: Yet another example of people over-playing something that is well known. We looked at the trends that occur once you remove ENSO effects and they are still just as large. Press release statements that imply the contrary are just wrong. – gavin]
From the quote Brian posted from the article he cited at #246:
“warming of the Arctic Ocean due to enhanced solar heating associated with sea ice loss may provide additional forcing to the overlying atmosphere, although Singarayer et al. (2006) has shown this effect to be small. In addition, warming of the high latitude north Pacific and Atlantic Oceans due to enhanced downward turbulent energy fluxes as a result of anomalous warm air advection out of the Arctic may also alter the atmospheric circulation response through feedbacks with the midlatitude stormtracks…”
Could someone help with a translation for the (marginally) intelligent layman? If the anomalously warm air from the Arctic “alters” the atmospheric circulation response, what would that mean for weather on the ground?
#249 Rod B
Article
http://www.arctic.noaa.gov/essay_serreze.html
Image
Figure 1. Sea ice reflects as much as 85% of solar radiation hitting the surface, hence absorbing only 15%. Ocean water, by contrast, reflects only about 7% of solar radiation, absorbing 93%. (Courtesy Don Perovich, CRREL)
I’m not sure about the specifics of what you are saying, but my point was general in nature regarding Arctic Amplification. The point of the post was to give an idea of the ice albedo with regard to amplification effect in order to get an idea of what will happen as the summer ice reduces in the Arctic. I think the image does that well.
This is only speculation on my part (my part being an art major college dropout Dunning-Kruger exemplar), but I think that the loss of summer ice cover on the arctic will have the following consequences:
A. Expansion of the polar cell driven by evaporation of moisture from open seawater; this is supported by the increase in precipitation over Siberia, Canada, and Greenland seen in the models of Deser et al 2009.
B. General easterly winds around the Arctic coast driven by the coriolis effect on the polar vortex will couple into the now open water causing (intermittent?) clockwise surface currents; these will converge with the warm(ish) Gulfstream waters from the Barents sea northeast of Svaalbard, transporting warm salty water northward. As these waters freeze, the cold, salty brine sinking will drive more bottom water south through the Fram Straights; i.e., drive the circulation of the AMOC further north.
C. Exposure of open water to wind will mix the ice derived fresh water with salty surface waters, The process of melting, mixing, refreezing and expulsion of cold dense brine will “pump” salt down in the Arctic sea, giving fresher surface layers and saltier bottom water.
D. The increase in precipitation and snowpack will give higher river flows during spring melt (and more floods like recently seen on the Red river), further freshening the Arctic ocean surface. The increase in snowpack may act to protect the permafrost from melting, or the increased transport of latent heat mey do the opposite; accurate modelling, or time will tell.
E. The expansion of the polar and Hadley cells will compress and intensify the Ferrel cell(s); this will cause more variation in the jetstream, both position and strength, as Tenney expects. We will see a continuation of the trend to more intense storms, higher peak to average rainfall, and more wind/flood damage in the northern temperate zone.
F. The easterly winds coming over the increasingly open water of the Barents and Greenland seas will drive more heat (latent and sensible) onto the lower eastern parts of Greenland, increasing the ablation of the glaciers and ice sheets below the accumulation line, and may drive the accumulation line to higher elevations, increasing the ice loss from Greenland. Snowfall will increase at the higher elevations, resulting in accumulation and thickening in Greenland’s interior. The increase in gradient will speed flow from the interior to the coast, and the net mass loss will continue to increase, following the currently observed trends.
G. Wind driven mixing of open warm surface water with cooler layers below will transport more heat to the methane hydrate layers of the East Siberian Shelf, continuing the trend of increasing evolution of methane observed by Igor Semiletov,Natalia Shakhova, and others. (see http://www.nature.com/climate/2009/0904/full/climate.2009.24.html and http://www.nature.com/climate/2009/0904/fig_tab/climate.2009.24_F1.html. I wonder if Tamino would be interested in calculating the correlation coefficient between the methane increase and arctic sea ice loss &;>)
266 Ike. Your last paragraph. You suggest that the doubling of CO2 will lead to permafrost melting and release of the trapped GHG. That release is temperature-defined rather than based on CO2 concentration isn’t it.
That worries me a lot, because in the paleoclimate record the rate of change was of the order of +0.1K per century, possibly less. And the Lag between temperature rise and the observed CO2 increase is something in the range between as little as 200 years and maybe 800. So the temperature rise that triggered the CO2 increase is somewhere in the range of 0.2 to 0.8K. Which is roughly where we are now, isn’t it?
Of more interest than Carter’s paper cited above might be Lindzen’s latest, in which he argues that negative feedbacks reduce sensitivity to 0.5C per doubling of CO2.
Will you guys take a shot at dismantling it? It’s already making its spread throughout the denialsphere…
Regarding the consequences of an ice free summer Arctic:
Most people following AGW are familiar now with the stories about permafrost melting and the ensuing positive feedback, etc. Last year I ran across another theory and I’d love to hear the opinion of people who know and understand more about these things.
Tom Wysmuller, a retired meteorologist, acknowledges Global Warming is happening and that it is being caused by human activities. His theory however is that as the Arctic sea loses more and more ice during summer melt there will be a counter-intuitive flip that will bring on a new ice age instead of further global warming. This theory is based on Ewing’s and Donn’s theory from the 50’s, see Spencer Weart’s site: http://www.aip.org/history/climate/simple.htm#L_M007
To quote his webpage:
“As more Arctic Ocean becomes exposed for longer times before being sealed by seasonal pack ice formation, snows will fall earlier each year, in larger amounts, and linger on the ground longer into the spring. Albedo reflectivity from snow is negligible during the dark arctic winter, but both in early fall, and as spring arrives, the snow in higher latitudes remains on the ground longer, and reflectivity increases. Thus the central US and the East Coast will experience cooler springs and the transition into summer temperatures, although somewhat later, will be relatively rapid. The US West Coast will have warmer springs and summers, as will Western Europe. Warmer weather will linger through October’s end almost everywhere, but winters will be sharply colder. The massive pack-ice loss of 2007 set up ocean effect snows on the Arctic Shores that increased reflectivity. Colder Northern Hemisphere winters with sharp temperature contrasts are an inevitable result.”
Unfortunately there isn’t more information on the website: http://www.colderside.com/faq.htm, though the author did send me a few pdf’s containing research by Ewing and Donn.
Brian Dodge in #275 coincidentally wrote: “The increase in snowpack may act to protect the permafrost from melting, or the increased transport of latent heat may do the opposite; accurate modelling, or time will tell.”
Now, I know from Spencer Weart’s website that climate science finally rejected the Ewing-Donn theories (this is what I was told last year upon inquiry here as well), but does it nevertheless hold any merit whatsoever? I myself find the idea of the permamelt-feedback more plausible (because of the CO2 forcing etc), but as I understand it nobody really knows what the consequences of the decreasing Arctic sea ice extent will be (hence wili’s questions as well). I hope this question isn’t considered too silly! If so, I apologize.
#275 Brian, nice to read this kind of dissertation. Was there any common knowledge with respect to inversions? Its a key issue, warmer Polar oceans and thinner ice affects the very structure of Upper Air layers. The long term data with respect to inversions is a bit muddled by resolution problems with changing radiosondes having different instrument errors. The other important question is what GCM’s predict, it is surely linked with thermal IR effects.
Off-topic, but “Ancient Maya Practiced Forest Conservation 3,000 Years Ago”
http://www.sciencedaily.com/releases/2009/07/090722150825.htm
and then stopped. So it may be that the long drought which ruiined Mayain civilization was brought on, in part, by their own actions.
Re: #257
Dear wili,
Please note that I am not a scientist.
Re: #267
Dear Rod B,
Change in albedo due to loss of the Arctic Sea ice is but one factor, but I would have assumed that you already knew that.
Re: #273
Dear wili,
“If the anomalously warm air from the Arctic ‘alters’ the atmospheric circulation response, what would that mean for weather on the ground?”
wili, I am sorry to have to tell you this, but what this all means is that everything we thought we knew will become wrong and useless.
Now, you may or may not have noticed, here on many threads at realclimate, there seems to be a real joy in the fellowship of the exchange of numbers and formulae. Most of these numbers thus exchanged and chewed over will have little significance in the long run or in the big picture, but it seems to be a type of comfort to these gentlemen. At the risk of offending the gentlemen here, I will point out that this is usually a male activity. More power to them, if they enjoy it.
Sometimes, I think it is their way of dealing with the inevitable by sort of ignoring it (“it” being that 10-ton elephant in the room).
And, I think you know in your guts just how to translate into layman’s terms that article’s quote.
Re: my comment #240
I did phrase that rather badly making it appear that all was related to changing albedo.
Of course, that is not correct.
But, while we are on the subject, let’s have a look at the resulting SST anomalies:
http://www.osdpd.noaa.gov/PSB/EPS/SST/data/anomnight.7.23.2009.gif
Well, speaking as another artist I have to say hats off to Brian Dodge; I wish I understood all this stuff as well as he does. I got fossicking around about the thermohaline thanks to a pseudoskeptic and learned a lot (talk about doing evil that good may come!).
Part of my problem is that I forget that one thing causes another and then another, and the sum of all this may be a little counterintuitive. Also, science is a little slow for those of us who want fireworks (not to say we aren’t getting ’em on a scale we wish we weren’t, natheless). Tenney helped me – info neat but not gaudy – much of it visual and simple enough for my lay understanding.
http://climatechangepsychology.blogspot.com/
172. Ike Solem
Thanks for your usual patience coupled with information.
Hats off to the team of refreshingly honest questioner wili, Brian Dodge, and Tenney as well as this pearl:
http://www.cdc.noaa.gov/people/michael.alexander/Deseretal.seaicesubmit.2-09.pdf
“The Seasonal Atmospheric Response to Projected Arctic Sea Ice Loss In the Late 21st Century”
—
There’s a certain Alice in Wonderland quality to the arguments going back and forth. I’ve tried this, I’ve tried that, nothing works …
People have tried to answer quibbles that lack scientific backing politely and in detail, and they’ve tried doing it less politely, but the banging around and rattling the cage keeps coming up with the usual – turning words around into complaints about attacks. As it kidnaps discussion perhaps it’s best to leave the trolls alone. People who have made their mind up based on pseudoscience (or worse – the closed mind is the giveaway); you get this kind of thing
“One of the best ways to tell if people are on “thin ice” with their arguments, is the their use of condescending remarks.”
Doug Bostrom 173 tries very hard to make this explicit:
“Rude and obnoxious replies are not particularly unusual here when RC regulars are confronted with stale talking points coupled with pugnacious presentation. Repeated exposure to expired canards elicits a positively allergic response. If you can’t stand heat, don’t turn up the thermostat.
“If you’re a thin-skinned “skeptic” and imagine you’ve got a beef to pick with any particular facet of climate science, why not first make sure of your facts, then present your “finding” with a neutral affect?”
Dr. Reisman in 194 has also named it well.
“Nay, we mere mortals must bow down to the anonymity of the splendor of masked diatribes, non sequitur arguments, straw-men, false dichotomies and red herrings and wallow in our foolish consideration of the works of scientists who are guilty of examining evidence using such device as the relatively unestablished scientific method…. because everyone knows that the climate has been around much longer that the scientific method…, at least on this planet.”
—
Presenting useful information will restore the life to the conversation. I think there have been enough replies to clear the air for the rest of us.realize how refreshing it is to have real questions that start a real discussion – nice!
The Moon and tides again (I’m reporting this because I have now received some interesting information, a few of you seemed interested, and I said I would post on this topic when I had learned more):
Hank posted a link to a Nature Geoscience paper, but I’m not presently at a location where I can access it. I contacted the author to request a copy and Dr. Bills kindly recommended another paper as well. This paper (Munk, W. & B. Bills, 2007, “Tides and the Climate: Some Speculations”, Journal of Physical Oceanography) has lots of interesting stuff, personal and scientific. From the abstract: “The obliquity modulation of tidal mixing by a few percent and the associated modulation of the [MOC] may play a role comparable to the obliquity modulation of the incoming solar radiation.” They’re not talking just about the Moon’s gravitational pull on the Earth, but also other gravitational interaction effects with longer periodicities. I’m going to share some interesting/fun quotations from that paper and then a comment Dr. Bills made in direct response to my question about the Moon and early Earth climates:
“The proposal for a long-period modulation goes back to Loder and Garrett (1978) who attributed an 18.6 yr cycle in ocean surface temperature to shallow mixing associated with the lunar nodal tide cycle. Otto Pettersson in 1910 discovered internal tides breaking over the bank that separates Gullmarfjord from the sea and spent much of his subsequent career trying in vain to convince his colleagues that tidal mixing is a factor in ocean climate…. A few decades ago the suggestion that the Moon played a role in determining global ocean properties was considered lunatic; now it is considered obvious…. There is wide agreement that pelagic tidal mixing must be taken into account in any realistic modeling of ocean properties. But we are a long way from understanding the underlying physics, and depend heavily on a parameterization of the processes involved.”
“Mixing is associated with the tidal current, and not the tidal elevation.”
“Given the appropriate long time constants of global ocean overturning, the weak obliquity tides might play a role in ocean climate; it is a matter of joules versus watts.”
“We end up with an effect of (allegedly) significant magnitude but unknown sign, hardly a satisfactory situation.”
“Solar radiation directly delivers energy to Earth’s surface, whereas tidal mixing modifies the poleward transport of heat by the MOC, with large (and unknown) phase lag.”
“The rising sea level [referring to ends of ice ages] significantly alters the depth and dissipation in the shallow seas; Egbert et. al. (2004) estimate that the North Atlantic tides during glacial times were 2 times as high and the pelagic dissipation almost three times the present rate. These feedbacks dwarf the astronomic forcing. But the numbers will not go away. It takes 10^25 J to melt enough ice to raise the sea level by 120 m. This corresponds to only 300 yr of the 10^15 W flux. A 3% increase in the MOC heat flux could account for the entire melting.”
I am thankful to Dr. Bills for offering some additional information. To summarize, “tidal heating scales roughly as the inverse 6th power of distance to the Moon.” Therefore, he says, it is conceivable that tidal heating could be comparable to radiant energy when the Moon was 10x closer to Earth (a million times more than tidal heating yields now). But this would only have been for a few million years. Dr. Bills ensures to include caveats regarding extrapolating models too far, and in fact there perhaps IS NOT acutally a young faint Sun paradox for such reasons.
Interesting tid-bit: “Tidal heating, at present, generates about 3×10^12 W. That is roughly the amount of energy in the global electric power grid.” So if electrical power could be perfectly converted into heat, the present warming effects of tides would be similarly small (warning: my own layperson’s interpretation), although I suspect the fact that the tidal heating is dissipated largely in the oceans makes it more important.
I hope you find the above interesting. I suspect Thomas won’t like this post very much, as I doubt much of it is new to him.
SecularAnimist #272:
Tamino has already posted a thorough debunking of the McLean, de Freitas, & Carter (2009) paper. The authors have applied a manipulation to the data that first removes the trend in temperature rise. They then claim that because their analysis of that manipulated data finds no correlation between the temperature trend (which has been removed) and CO2, CO2 can’t be having an effect. Based on their method and illogic, their analysis would have come to the same conclusion no matter how tight the correlation between CO2 and temperature.
Tamino has a discussion of the Freitas/Carter paper on “Open mind.”
For a somewhat different perspective on the significance of Arctic sea ice melt, see “UNDERSTANDING RECENT VARIABILITY IN THE ARCTIC
SEA ICE COVER – SYNTHESIS OF MODEL RESULTS AND
OBSERVATIONS,” John Whelan September 2007, Naval Postgraduate School thesis, Monterey CA
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA474361&Location=U2&doc=GetTRDoc.pdf
“The changing conditions in the Arctic Ocean are of significant importance to the national security interests of the United States spanning across several areas of concern including: national defense, territorial integrity, freedom of navigation, commerce, energy resources, environmental protection, and search and rescue operations. Although the wide-ranging implications of diminishing sea ice will affect multiple federal agencies, the greatest impact will be felt by the U.S. Navy as it reshapes its strategies and policies to adjust to the changing physical and political environment.”
Also note-“Approved for public release; distribution is unlimited”; I wonder what is in the papers “not approved for public release; classified”?
Doug Bostrom #265
Not the only thing BobFJ is missing, and not even the most important. See my correction
.
Kevin McKinney, Brian Dodge, Ike Solem, Anne van der Bom & Sidd:
Did you notice these two summertime aerial photos on the ‘U.S. Geological Survey’ site that I cited above?
(entitled) ‘Somewhere over the Grand Chasms, 1957’ [Filchner ice shelf; at an early stage of break-up]
http://earthshots.usgs.gov/Filchner/FilchnerChasms1photo.jpeg
http://earthshots.usgs.gov/Filchner/FilchnerChasms2photo.jpeg
I’m still flummoxed by some vague statements something like “massive melt ponds”, (but presumably in an unrelated dynamic on the Greenland icesheet?), and “melt ponds were observed, (presumably by satellite?), shortly before break-up” of one or more of the Antarctic ice shelves recently.
I don’t know if you have caught-on yet but these mechanical hinging failures of ice shelves do not happen overnight, but perhaps over a decade or so. So why would melt ponds suddenly appear shortly before break-up? Could it be instead that there has eventually been total physical separation across the canyon, (chasm), that allows sea water to rise to around 90% of the surrounding ice thickness shortly before the separation is observed to accelerate?
BTW, the freezing point of sea-water is about 2C lower than fresh.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kevin McKinney, Reur 204:
Thankyou for your response, which in the first part was:
Just taking your first line, the purpose in the experiment in selecting flexible flat sided containers was to precisely demonstrate that the freezing of water did NOT exert any discernable “pressure” on the open container. Why you imply that a more rigid container of ice would give a different result is a puzzle to me, as are some of your other points. Also, when water freezes in a container, there is no longer any hydrostatic pressure. (in any direction). Sorry, but that is all I have time for right now.
Oh BTW, quickly, the dynamics on the Greenland outer (lower) ice SHEET which is substantially geologically captive in a basin, are different to heaving ice SHELVES in Antarctica.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ike Solem,
Thankyou for your interest and two thoughtful posts.
I’ll try to respond soon…. I do have some other things on the go.
re # #277
dhogaza, I wonder whether the “denialsphere” will be so interested in puffing Amy Clement et al.’s study reported in today’s Science, which shows evidence for a positive cloud feedback in the Northeast Pacific.
Their analysis yields an interpretation consistent with a climate sensitivity on the high end of the IPCC range (i.e. > 4 oC per doubling of CO2).
Personally speaking, I think we’re in the early days of attributing cloud responses and their impacts, and this is far from being a conclusive finding. However it will be interesting to see how the dodgy-bloggers deal with these two papers….!
http://www.sciencemag.org/cgi/content/abstract/325/5939/460
Amy C. Clement, Robert Burgman, Joel R. Norris (2009) Observational and Model Evidence for Positive Low-Level Cloud Feedback Science 325, 460-464. (July 24, 2009)
abstract: Feedbacks involving low-level clouds remain a primary cause of uncertainty in global climate model projections. This issue was addressed by examining changes in low-level clouds over the Northeast Pacific in observations and climate models. Decadal fluctuations were identified in multiple, independent cloud data sets, and changes in cloud cover appeared to be linked to changes in both local temperature structure and large-scale circulation. This observational analysis further indicated that clouds act as a positive feedback in this region on decadal time scales. The observed relationships between cloud cover and regional meteorological conditions provide a more complete way of testing the realism of the cloud simulation in current-generation climate models. The only model that passed this test simulated a reduction in cloud cover over much of the Pacific when greenhouse gases were increased, providing modeling evidence for a positive low-level cloud feedback.
John. P. Reisman, Reur 274:
“…I think the image does that well…”
http://www.arctic.noaa.gov/images/icealbedo-sml.jpg
Quickly; sorry; but the image you cite is extremely simplistic. Most people agree that when the sun does appear in the Arctic, its zenith is rather low in the sky. This has a profound effect on the reflectivity of water. Take a look at the sun as it sets over a large expanse of water, and you should be able to understand what I mean.
Martin Vermeer Reur 290
Yes, you are right I did miss that point, but quickly, the fundamental thing is that all ice shelves frfacture, regardless of thickness, such as the calving of A24 at 400 metres thick, compared with the more recent failures between 200 and 250 metres thick
Brian Dodge, thanks for the great information and sources!
John P. Reisman
Citing a press blurb by Mark Serreze of NSIDC you wrote to Rod B (274):
“Sea ice reflects as much as 85% of solar radiation hitting the surface, hence absorbing only 15%. Ocean water, by contrast, reflects only about 7% of solar radiation, absorbing 93%”.
These values may be true on average, but studies have found that at Arctic/Antarctic latitudes the surface albedo of seawater varies between 25 and 40%, depending on the waviness of the water.
http://www.terrapub.co.jp/journals/JO/JOSJ/pdf/2104/21040148.pdf
The surface albedo varies strongly with the angle of the sun, so that at the higher latitudes (which have a greater percentage of the sea ice) the albedo is nearer to the higher end of the range (but let’s take the arithmetic average of 32.5%).
As pointed out by Serreze, sea ice has a higher albedo. The estimates I have seen put this at around 80% (high end of the range).
Based on a quick look at the satellite photos, let’s assume that half of the Arctic surface area is covered by clouds, which reflect incoming solar radiation, so that its surface albedo is essentially unaffected by the state of the sea below (ice or water).
The Earth is said to have an “average” surface albedo of around 30%.
To what extent has this been impacted by melting sea ice to date?
NSIDC data show us that the average summer-month (April-September) Arctic sea ice extent was 10.93 million km^2 (1979-2000 baseline) and 9.87 km^2 (latest 2008/09 values).
At the same time Antarctic sea ice extent was 9.66 million km^2 (1979-2000 baseline) and 10.09 million km^2 (latest 2008/09 values) for the summer months there (October-March).
Globally the sea ice extent has declined on average by 0.62 million km^2. All of this surface area is exposed to the sun during the summer months, but half was covered by clouds. The Earth has a surface area of 510 million km^2, of which half is exposed to the sun.
So, if the surface albedo was changed from 80 to 37.5% due to melting ice, this means that the average albedo of the Earth was lowered by 0.06% (from 30% to 29.94%). Not much of an “albedo feedback” there.
This is obviously not a problem.
Let’s assume that the more alarming predictions for the future are correct and that there will be a major meltdown of Arctic ice leading to an “ice-free summer”.
NSIDC’s Mark Serreze says this could happen by 2030 if melting rates accelerate; other estimates put it closer to 2070-2100 if melting rates remain the same as they have been recently. Let’s also assume that the Antarctic sea ice stops growing and remains the same as today.
If we assume that there is no Arctic sea ice for a full 31-day period in August/September of some future year and that the remainder of the “summer ice” is reduced by one-half on average, we have a “disaster scenario”.
On this basis we have a reduction of sea ice of 5.3 million km^2 for 31 days and 6.0 million km^2 for 152 days, leading to a reduction of the Earth’s average annual albedo of 0.3% (from 30% to 29.7%), if we assume that half of the area is covered by clouds and unaffected. Even if we ignore the clouds we still only arrive at an albedo reduction of 0.6%.
These figures are based on a rough calculation that could be refined, but the conclusion will not change by very much.
My question: other than any regional impacts that this may have in the Arctic, is this a major cause for concern and, if so, why?
Max
Bob_FJ
Reur 293 on seawater surface albedo at high altitudes, the message I just posted to John P. Reisman has an attached study, which confirms what you are saying.
http://www.terrapub.co.jp/journals/JO/JOSJ/pdf/2104/21040148.pdf
At Arctic/Antarctic latitudes seawater has an average surface albedo of around 32%, depending on the waviness of the water. This compares to an albedo of around 80% for ice (upper end of the range of estimates I have seen).
I’ll post the link again in case my other message gets stuck in the incoming filter.
Max
BobFJ
24 Jul 2009 at 2:20 am
Pretty pictures you posted. I might be mistaken, but it seems you’re just posting them and let everyone do the guesswork of what exactly it is you’re trying to say. To keep up the appearance that you actually have anything to say.
Let me formulate your hypothesis as follows: “The recent collapse of ice sheets is solely caused by mechanical hinging forces”.
Prove your hypothesis.
Not – as you have done until now – by throwing doubt on the counterhypothesis (that global warming is just the tiny change in circumstances that are necessary for those ice shelves to find themselves in a place where they no longer can exist). No, you start by supporting your hypothesis with evidence. I suggest you start off with the observations regarding the changes in those mechanical forces over the past decennia.
Re #271, Doug, that article is interesting but its all about getting your head around the numbers. As an example, energy usage in terms of the KWh. If a computer burns 100W of energy then after 10 hours it will have used up 10×100 Watts = 1 KWh in 10 hours. Now lets scale that up to the size of countries shall we. 1000 KWh = 1 MWh and 1000 MWh = 1 GWh and 1000 GWh = 1 TWh!
USA = 29,000 TWh (thats 12 zeros added making an astronomical number). Of that 3,900 TWh is purely electricity. 200 Two MW (a measure of power) Wind Turbines will produce 1 TWh of energy a year. So 200 x 3,900 = 800,000 Wind Turbines. Thats a lot.
No wonder we are in denial beccause oil usage makes up another huge number of that 29,000 TWh and replacing that is another massive operation even if everything is 50% more efficient. I am sure that Wind, wave, solar in all its forms deployed on a massive scale along with a lot of nutural gas increased usage can get rid of coal and eventually oil and gas usage but its a massive ask!
BobFJ, an “open” container a few centimeters deep isn’t a good analog for a glacial crack many meters deep. And obviously, the closed container case shows what the pressure can do. But are you losing sight of the fact that part of the question was whether there would be freezing at all? Your intuitive assumption was that it must. Direct onsite observations–draining of meltponds via moulins–show that that’s not always the case, however. (And yes, this part of the discussion was about glaciers, not sea ice.)
Part of the reason for this discrepancy might lie in the way you conceptualized the problem. You wrote that the water in a crack “loses contact with the warm air that created it” and hence should freeze. But 1) it isn’t necessarily the air that “creates” the melting; radiative heating can do that. It’s very directly observable on a sunny March day in Sault Ste. Marie, where I grew up. All you have to do is look at the south vs. north sides of snow banks, preferably on a day when the air temp is still at freezing point. 2) It isn’t necessarily the case that the water in the crack “loses contact.” There’s a big old melt pond up there, remember? It remains “in contact” with the air–and with the radiation. And the cracks can be large enough that some mixing still occurs. Perhaps most importantly, the crack may well have an outlet, in which case you get a large heat transport down into the ice, and freezing is much less likely.
Turning to your other post regarding sea ice and solar zenith, your point about the effects of water albedo change being minimized by the low Arctic solar zenith is true as far as it goes. But it ignores the fact that direct solar radiation is only part of the picture. Albedo is not only an issue at optical wavelengths, but at infrared wavelengths. Back radiation in the infrared will not be reflected by the water due to angle of incidence–and, according to Kiehl & Trenberth ’98, this is an input roughly twice as large as direct insolation. (Moreover, that low zenith also means a nice long path through an atmosphere which, with less sea ice, will have a higher absolute humidity, and hence enhanced absorptivity–not an albedo effect, I know, but it’s going to enhance warming all the same.)
You can’t wish away the consequences of sea ice loss quite so easily!