“Six scientists from some of the leading scientific institutions in the United States have issued what amounts to an unambiguous warning to the world: civilisation itself is threatened by global warming.
They also implicitly criticise the UN’s Intergovernmental Panel on Climate Change (IPCC) for underestimating the scale of sea-level rises this century as a result of melting glaciers and polar ice sheets.
Instead of sea levels rising by about 40 centimetres, as the IPCC predicts in one of its computer forecasts, the true rise might be as great as several metres by 2100. That is why, they say, planet Earth today is in “imminent peril”…
Read the complete article entitled ‘The Earth Today Stands in Imminent Peril’ by Steve Connor: http://environment.independent.co.uk/climate_change/article2675747.ece
The piece finishes with comment that “a feasible strategy for planetary rescue almost surely requires a means of extracting [greenhouse gases] from the air.”
“Alfred Wong of the University of California, Los Angeles, at last week’s meeting of the American Geophysical Union, in Acapulco, … reckons the problem is not so much that CO2 is being thrown away, but that it is not being thrown far enough. According to his calculations, a little helping hand would turn the Earth’s magnetic field into a conveyor belt that would vent the gas into outer space, whence it would never return…
Read the compete article from The Economist entitled ‘Stairway to Heaven’ here: http://www.economist.com/research/articlesbysubject/displaystory.cfm?subjectid=348924&story_id=9253976
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
This is Hansen in his standard “Dopi Wan Kanobi” drag. The analysis of past ice sheet declines is of minimal relevance to remnant ice sheet behaviour in an interglacial period like ours.
The concept of “albedo flip”, the latest incarnation of the discredited “tipping point” theory, is only relevant in periods of extreme glaciation when ice sheets extend into lower latitudes. At lower latitudes the angles of solar incidence are sufficiently high enough to make changes in albedo (the percentage of reflected insolation) a relevant impact.
In the places where ice sheets are now present, the angles of solar incidence remain too low to make much difference. This is particularly so with the change from ice pack to ocean as the reflection from water at very low angles is not significantly different to that of ice.
It should be noted that the graph on ocean reflectivity at wikipedia http://en.wikipedia.org/wiki/Reflectivity appears to be ass about as it appears to suggest that light absorption is highest at the lowest angles. But the graph actually measures reflectivity at various departures from the “normal” angle (ie 90 degrees) so an angle of 85 degrees on the graph is actually an angle of incidence of only 5 degrees.
As any observer of sunrise or sunset over water will attest, albedo is highest at the lowest angles of incidence. As wiki states;
“Although the reflectivity of water is very low at high and medium angles of incident light, it increases tremendously at small angles of incident light such as occur on the illuminated side of the earth near the horizon (early morning, late afternoon and near the poles).”
This latter point about the poles is highly relevant because at high latitudes the angle of incidence is splayed both laterally and longitudinally. So while the mid-day angle at summer solstice may still be in the range of angles where albedo changes are significant, this is shortlived as most of the extended daytime is at low angles of incidence.
Only when ice caps extend well below the Arctic and Antarctic circles will the change in albedo from ice to water be a significant factor in heat balances.
For the mag CO2 jet to be a plausible cure we first have to admit AGW based on our extraordinary emissions is a real threat to life itself.
Ian Mott – “This latter point about the poles is highly relevant because at high latitudes the angle of incidence is splayed both laterally and longitudinally. So while the mid-day angle at summer solstice may still be in the range of angles where albedo changes are significant, this is shortlived as most of the extended daytime is at low angles of incidence.”
Only when ice caps extend well below the Arctic and Antarctic circles will the change in albedo from ice to water be a significant factor in heat balances. ”
Not sure that this is completely correct. Have a look at this handy sun angle calculator.
http://kensolar.com/tek9.asp?pg=support&article=46
If you put in 60°N you can see that for 8 months of the year the noon sun angle is 70° or below from the normal. From the graph that you supplied the reflectivity of water is 1/10 that of ice so that ice at 60°N is 10 times more reflective than water even with after the incidence angle is taken into account. 60°N is the start of the Arctic circle. Even at 70°N there is at least 6 months of the year when the sun is shining from an angle of 70° or less normal to the surface which means that the loss of ice in this latitude will result in a surface that is 5 times less reflective than ice for most of the year.
Therefore I think that it is a bit hasty of you to conclude that only when the ice caps extend beyond the Arctic circle will the changes in albedo be significant.
Ian
it only takes a small change in temperature for significant changes to biological systems to happen. Just look at the human body if it’s temperature goes up by 1C. We usually refer to temperature in degrees C, but that is a convenience for us. In absolute Kelvin, the temperature of the Earth just has to change by a surprisingly small percentage for an ice age to come and go, along with mass extinctions.
Leave it to SJT to bring up Al Gore’s “fever baby” analogy.
Wow! It that doesn’t define what’s wrong with atmospheric modeling, what could?
Welcome back, Ender. Your interpretation of the graph is correct, but only at Noon each day. So when we see that a midsummer Noon angle at 60N is 53 degrees we must remember that this is the very maximum angle for a small part of the day.
As these high latitude midsummer days are also very long days there is a tendency to assume that the angles will remain in proportion to those at lower latitudes. But the high latitude means that noon time angles are very brief as a much greater proportion of the day experiences lower angles of incidence.
The best way to understand it is to get a ball and point a pencil at a location close to the pole, at 23 degrees above equatorial, and off-centre so one can see how the angle of reflection is splayed both laterally and longitudinally. Divide the ball into quadrants and one can see that only one quadrant would be in twilight while three obtain some direct light. But two of those remaining quadrants are at very low angles, demonstrating that the polar day may be longer but the light is generally at lower incidence.
And this has three main implications.
1 a given square metre of sunlight is spread over a wider surface, thus diminishing it’s intensity,
2 that given square metre of light must pass through more atmosphere to get to the point of contact, and
3 the given square metre of light, in it’s doubly weakened state, will then have more of it reflected.
I don’t have the maths to be able to calculate the real angle but do recall working it out with compass and protractor in a class room long long ago in a galaxy far far away.
It also seems likely that Hansen et al have failed to account for the fact that past warming at the end of glaciation periods was assisted in no small part by orbital and rotational changes that have had the effect of shifting what was once polar ice to a new location at a lower latitude where angles of incidence and albedo factors are more intense.
That is all very well SJT, but if we are to express change in terms of Kelvin then we must also express the temperature anomalies in Kelvin as well. Put that on a graph and the reaction of every reader would be, “what temperature change?”
Ian – “Your interpretation of the graph is correct, but only at Noon each day. So when we see that a midsummer Noon angle at 60N is 53 degrees we must remember that this is the very maximum angle for a small part of the day.”
Thank you – that is true however there is a significant part of the day, especially in summer, even at these high latitudes where the sun is sufficiently high to not be directly reflected from the sea as if it was highly reflective surface. In fact you need the sun angle to be approx 10° or lower (from the average polarisation) for the water to have half of reflectivity of ice. Even at these low angles the sea is absorbing twice as much of the radiation as it would if it was ice. I am sure you will agree this is still a significant difference.
Even worse is that this graph is for still water. The sunset over the dead calm sea is indeed a picture with the rays of the sun beautifully reflected over the ocean. (You can tell I live in WA). However I am sure such days at 60°N are very few and far between and the sea, far from a picture perfect surface, would be rough with significant wave action presenting all sorts of angles to the sun.
The difference in albedo between rough seawater and ice even at low sun angles would be far greater as the surface would very rarely be still enough for the reflection of the low angle sun to significantly raise the albedo toward that of ice.
I really think that you would have to agree with Hansen that the loss of ice at around 60°N and S will greatly reduce the albedo of the Earth which in turn will enhance the warming already present.
I see your point, Ender, but it is wrong to be using 60N as the example. The current northern boundary of summer pack ice is 80N and that, or higher, defines the angles of relevance to Hansen’s scarenario. The Noon angles at 80N are;
Jan –
Feb –
Mar 10
Apr 22
May 30
June 33
July 30
Aug 22
Sept 10
Oct –
Nov –
Dec –
Clearly, only small departures from these angles will produce disproportionate increases in albedo. The key questions are;
1 how long is this “significant part of the day” that you refer to (which is only in mid summer)?
2 is this change in albedo significant enough to overcome the freezing induced by the absence of high angle insolation in the greater part of the year?
3 is this change significant enough to overcome the embedded absence of heat in the existing ice mass.
This link shows actual conditions at the North Pole. http://www.arctic.noaa.gov/np2003/gallery_np_weatherdata.html
Note that atmospheric mean temps, even in June, are rarely above Zero C with February mean of -31C, and that is before wind chill.
And as the wider sea ice at latitude 60 is only there in mid winter anyway then changes in it’s albedo are irrelevant.
Hansen appears to assume that ice, once melted, remains melted. But all the ice sheets are generally wide, flat surfaces where melt water will form shallow puddles in midsummer and freeze up again soon after. In fact, in many cases it would only take an increase in wind velocity to refreeze this melt water each night.
This is the folly of working with mean temperatures in models. It is far too easy to forget that a monthly mean of +1C, for example, still includes 30 nights (or half days) when temperatures were well below freezing.
There is one additional factor that blows Hansen clean out of the water as a blatant ‘AAA’ rated Scaremonger. CLOUD COVER
Take a look at this description of Arctic cloud cover in this report on an attempt to view an eclipse, and note,
“From the high Canadian Arctic to the Russian islands of Novaya Zemlya, the eclipse track crosses one of the cloudiest areas of the globe. Only in the Kara Sea between Novaya Zemlya and the Russian mainland does the relentless cloudiness loosen its hold and it is here that we have chosen to try for a view of the eclipse. The numbers are dramatic — an average monthly cloud cover of 93% near Spitsbergen Island drops to a more promising 67% over the waters east of Novaya Zemlya.”
http://www.tq-international.com/NorthPole2008/NPitinerary.htm
That is “an average monthly cloud cover of 93%” which all but the brain dead would have to concede renders all the tripe about altered albedo into unambiguous gross misrepresentation of fact.
For this albedo change scarenario to have any traction at all they would have to explain why a shift from sea ice to sea water would eliminate the pervasive Arctic cloud cover.
It is bollocks and Hansen is either completely out of his depth or he is a blatant planet pimp, bent on withholding vital information from all humanity.
Gee you’re clever Ian – I bet Hansen and his modellers never knew any of this. They’ll be really surprised when you tell them.
“Cripes – that’s where we’ve been going wrong”. “We have these state-of-art GCM we bought from Arfur Daly and they don’t have the correct sun angle programmed. Wow !”
“And I told those modelling blighters to look at albedo – maybe they’ve taken the research funds to the races again”
“Gee those Aussies are really smart – why didn’t we think of that”.
Funny that the melt rate is exceeding their modelling though don’t you think. Naaah !
And I wonder why it’s melting when Mottsa have proved to six decimal places that it can’t. I know the satellite obs are wrong. Yea that’s it.
There’s that earthquake tremor again.
Ian
my point exactly. The very small percentage in Kelvin that produces an ice age or massive change in the ecology due to temperature rise. What appears to be an inconsequential temperature rise on paper, then look at the Glaciers coming and going, along with mass extinctions. You may say it’s only a small change in albedo, that doesn’t alter the actual effect on the planet.
Of course if Hansen got all sophistimuckated he might have checked out satellite cloudiness like here http://xjubier.free.fr/download/GE_Files/en/kmz/June_World_Cloud_Cover_Map.kmz
Note Greenland.
Nice try at diversion, Luke, but 93% cloud cover renders all the rest of the discussion redundant.
My windows doesn’t recognise the file in that link. Try again with something else.
But you have tried that ploy before when cornered. That is “gee your so smart how come Hansen didn’t include it in his GCM?” The more important question is, why didn’t any of the sleazy slime balls mention cloud cover in any of their albedo bullshit?
If these guys are so emminent, how come they decided we didn’t need to know? My guess is that the dopey pricks have cloud cover in the GCM as a single constant rather than a geographical variable.
And again, Luke, your denial of the obvious is not masked by pathetic lines like “how come the ice is still melting.” The issue is not whether there is some modest melting, no-one disputes that. But if the current Greenland melt rate continues it will take 12 to 19 millenia for that ice to melt.
Hansen has claimed that “albedo flip” places the entire planetary civilisation in “imminent peril” and that this could take place in only a century or two. That is, 2.8 million Km3/200 years = 140,000 Km3 each year, or a 1000 fold increase in very short order.
Give us a break you sad little plodder. Get your tiny brain around the facts. If mean monthly cloud cover is 93% then 93% of the change in albedo from ice to water is totally irrelevant.
You are all exposed as a sleazy bunch of pathological liars.
Mottsa has done his nana again .. .. who’s a bit of an old grumpy wumpy then – kitchy koo –
is it cloudy all the time. Does melting of any floating Artic ice affect sea level – no. Needless to say the Artic is melting at a rapid rate beyond model expectations. Why? It’s far from modest. There is mounting evidence that Greenland ice sheets (which will increase sea level) are starting to see movement. They don’t melt as much as slide from smaller amounts of surface melting getting into groundwater.
And guess what – looks like low cloud over Greenland. Who’d have thought?
Given you don’t know how clouds are handled in the models you’d be ignorant as paddies pig. Which you are. So this has been a very instructive session – it’s suddenly dawned on me that you really are a total flake and have no idea. We’d been giving you some credence. But now you’ve been caught red handed talking twaddle.
What a great wussy windbag you are really. Go and deflate quietly. Then install Google Earth and you will notice that a .kmz file is read by Google Earth. http://earth.google.com/download-earth.html
You can check if your beloved tattered atlas is actually correct.
Fascinating – we have 3D satellite maps of clouds. Duh -I wunder if dem klimate moodlers no bout dat?
Following up in detail now at http://xjubier.free.fr/en/site_pages/SolarEclipseWeather.html
Google Earth 3D allows an interesting examination of Arctic cloud cover including the atypical areas of Spitsbergen Island and Novaya Zemlya. And it seems that the Arctic is somewhat less cloudy than Unca Ian suggests after reading his 1960 copy of Britannica. Check those boreal summer months. Oh dear.
“Sleazy pathological liars” hey. Well better than being a total numb nuts I guess.
Notice how Luke goes off topic and full of venom when cornered. Standard response from a captured thief.
For the record, the critical months of May, June and July, when Arctic angles of solar incidence are highest, the mean monthly cloud cover over the ice pack ranges from 60% to 80%. And the area mentioned in my above link, near Spitzbergen, is in the 80+% range.
It should also be noted that while central Greenland has cloud cover in the 40-50% range, the areas where surface melting has been recorded as expanding, nearer to the coast, still has a range from 60-80% cloud cover.
So surprise, surprise, just as in Antarctica, the coastal areas where most melting takes place are also the areas where most snow falls and new ice is formed.
And in Siberia where a lot more of this “albedo flip” is also claimed to be present, the cloud cover in June ranges from 60-80%.
And when we check out this graph at wikipedia http://en.wikipedia.org/wiki/Albedo we can see that the range of albedo values for snow (42% to 84%) is only slightly higher than the range for cumulostratus and stratus clouds (37% to 77%).
So while the theoretical albedo value for Arctic pack ice may be as high as 84%, the fact that the ice is covered by clouds for 60-80% of the time means the actual reflected energy is only a very small portion of that level because the clouds did the job first.
And when we take a good look at the midsummer cloud cover we get a good handle on what portion of atmospheric CO2 does not get to trap any heat inside our greenhouse because the clouds reflected the heat before it could be trapped by the CO2.
And it seems necessary to re-state that the studies of Greenland ice flow neglected to include the amount of new ice that is deposited each year. Dahl-Jensen’s analysis of annual layering, at http://www.awi-potsdam.de/www-pot/atmo/glimpse/pics/dethloff_greenland_JClim2002.pdf suggests this to be from 210mm to 230mm each year. And over the 1.5 million Km2 of ice multiplied by 0.00022km = 330Km3 of annual ice deposition. Current estimates of “rapidly increased ice loss” are only in the order of 230Km3 so Greenland may still actually be slightly lowering sea levels.
So no sign of any albedo flip any time soon.
It is also worth noting that this cloud cover mapping has used the preferred projection of the distorters and rorters, the old Mercators.
“distorters and rorters, the old Mercators.” – not if you’re clever enough to install Google Earth. But I think wee know the anshur to dat doont oui.
And Greenland is now lowering sea levels is it. I wonder why the sea level rate rise seems to be increasing then. Drat another annoying datum point.
I think we know who’s cornered.
The clouds reflected the heat before the CO2 got it. ROTFL. SO the poles are absolute zero now. Keep spinning Ian. You’re up the the axles in melting slush. See if you can cover the differential too.
You haven’t worked it out have you Ian. You’re having a youthful rediscovery of physics. (the loins may even start stirring soon after such a long rest). But I think the old GCM modellers may know a few things. Just call me intuitive. We’re still waiting your knowledge on how clouds are modelled. You’re the expert so tell us.
White noise follows .. .. ..
So here he is – deciding from first principles how GCMs work without finding out. Sea levels are falling – theya re? Ignores the latest GRACE mass balance numbers. Ignores the level of melting. Can’t install Google Earth. Ignores that ice pack decrease is outside the modelled values. Discovers albedo for the first time in history.
What a flake. And no wonder there’s earthquakes.
Did anyone notice the way Luke switched the angle. First we had Hansen making outrageous statements in print about how the sea ice will melt and produce his “albedo flip” which will then produce a dramatic collapse in Greenland ice.
But when Luke is presented with very good reasons why the sea ice pack may not completely melt, he does two tricks;
1 he switches the discussion directly to Greenland where there is zero prospect of an albedo flip because the sheet is 1.5km thick and the ice is on land, not seawater. And
2 he attempts to absolve Hansen from any blame for making media statements that completely ignore cloud cover, on the basis that cloud cover is factored into the GCMs.
It is a bit like excusing Christopher Scase for all his dishonest dealings on the basis that the truth was incorporated in his own private set of accounts.
The facts are that Hansen made public statements that left out any mention of the major element in the polar insolation equation. He did this in a way that would lead people to conclude that the melting of ice would result in the entire heat differential between snow and water would be absorbed by the Arctic Ocean in a way that would produce calamitous outcomes.
We can see in our own discussions on this and other threads, how discussion on albedo changes took place in a cloud vacuum.
So Hansen has knowingly made a misrepresentation by omission that has exaggerated the heat balance consequences of pack ice melt by a factor of at least 10.
And this omission of the role of clouds at the poles has enabled discussion on the behaviour of the Greenland ice sheet to take place without any consideration of the likely increase in cloud cover from greater exposed ocean surface, and resulting increase in precipitation and ice formation in the maritime regions of Greenland.
Note from the cloud maps how the maximum cloud cover is associated with the comparatively warmer water from the North Atlantic Drift. This warmer water brings warmer air and the warmer air is capable of holding and transporting more water vapour which, in turn, will deliver increased ice formation.
But Luke refuses to debate the facts. He is more comfortable making silly undergraduate sneers. It was such a good, positive and educational thread until he joined in.
And then Luke continues with his self serving distortions. I suggest that the largest part of insolation reflection is being done by clouds at the poles, not ice pack, for the very good reason that the light hits the clouds first, and “boy wonder” claims I am suggesting there is zero ice albedo. Straw man.
I simply state that my current windows xp system was not recognising the google earth files and the dumb turd claims I am unable to download google earth. I simply have not chosen to download it.
I note that the moisture balance of Greenland may be making a minor drawdown on ocean volume of about 100km3/year (0.3 of 1mm/year) and the dumb turd claims I am suggesting major drops in sea level. He deliberately tried to distract from the key point which was that Greenland has to lose 330km3 of ice each year to avoid being a net extractor of sea water from the worlds oceans. The same applies to Antarctica which must lose about 1000km3 of ice and melt water each year to avoid being a net extractor of sea water.
Luke knows perfectly well that I have been discussing albedo changes on this blog for almost two years and that discussion has included cloud cover and water vapour.
And the extent of his almost hysterical response to the issue of the lack of warming by CO2 in the atmosphere below clouds merely highlights the vulnerability of the CO2 Flux Clan to this highly relevant fact.
That is, the sum total of all atmospheric CO2 under all clouds makes a substantially reduced contribution to global warming because the clouds are already doing most of the job. As they have always done.
I am also on record as stating that the research that has provided the estimates of past sea level rises has been based on inadequate and unrepresentative samples derived from coral islands that are likely to be sinking while the more recent satellite data is of insufficient duration to be properly validated.
But as can be seen by the impact of Luke’s contribution to this thread, his intention was never to engage in informed discussion. All he has given us is the desperate distractions of a propagandista.
Lordy me Mottsa drones on doesn’t he.
Debating “facts” – with a Mottsa – come on.
A positive thread about throwing CO2 into space. ROTFL.
Ian stop stuffing around – cite here with references what Hansen has said. Not what fibs you’d like to concoct.
But anyway – I can imagine Ian cleaning his roof. It starts to rain. He loses his grip and starts to slide off slowly on a roof that’s getting wetter. He wife asks anxiously (lordy knows why) is he OK – his reply yes I’ve only slipped a metre at this stage. I can’t see what you’re fussing about. It’s gonna work out fine. My envelope tells mne I’ll be OK.
But anyway as fate would have it, one’s copy of National Geographic June 2007 turns up (I only read it for the pictures trust me). And low and behold we have a theme The Big Thaw… .. Wow !!
Johnaton Overpeck from University of Arizona says “There’s just unbelieveable warming in the Artic. It’s going much faster than anyone thought could or would”.
So Konrad Steffen from University of Colorado has been studying ice sheets. Apparently that icy Amazon – Jakobshavn has doubled its speed over a decade to 120 feet per day. Now discharges 11 cubic miles of ice per year.
Apparently some bloke called Eric Rignot has shown most of the southern Greenland ice sheets have accelerated, losing an estimated 54 cubic mile sof ice in 2005. Two of the outlet glaciers have since slowed down. But the GRACE gavity measurements a showing a slight decrease in Greenland’s gravity – implying a net loss of mass.
The scientists postulate that the ice mass is starting to stir.
And even though it can’t according to Mottsa’s envelope – apparently Greenland has warmed rapidly. 5 degrees at Stefen’s base camp. Over the last 15 years the melt season is getting longer, starting earlier and finishing later. Apparently instead of snowing it’s been raining.
And then there’s a fascinating beautifully drawn diagram of how it all works – rather craps in Mottsa’s envelope.
Apparently the meltwater (and now more of it) gets down the cracks, crevasses and moulins lubricating the base flow and speeds up the glaciers. At the margins warmer currents eat away at the grounding line.
Even more interesting is that Greenland ice is so heavy that it has forced the bedrock down into a vast basin, much of which is below sea level. Wouldn’t want the ocean to get in there would we?
Apparently similar things are happening in the Antarctic too. Gee is that right.
They also do a little rounds of the glaciers checking average change in metres of discharge thickness since 1977.
South Cascade, USA – 27.3m (that’s minus !)
Place, Canada -33.6m
Gulkana, USA -16.2m
Urumqihe, South No. 1, China -11.6m
Tsentralniy, Tuyuksuyskiy, Kazakhstan -16.1m
Midre Lovenbreen, Norway -12.3m
Austre Broeggerbreen, Norway -15.3m
Nigardsbreen, Normway + 13.8m (yep a plus)
Hellstugubreen, Norway -11.7m
Hintereisferner, Austria -20.6m
Sonnblickkees, Austria -14.5m
Careser, Italy -35.5m
Gries, Switzerland -22.1m
Saint-Sorlin, Switzerland -22.3m
Sarennes, France -30.8m
Echaurren, North Chile -6.4m
Chacaltaya, Bolivia – well since 1994 it’s become a boulder field (gone).
Gee Ian – I thought you said ice can’t melt. Don’t forget it can also slip !
“unrepresentative samples derived from coral islands that are likely to be sinking” – I just spat my coffee all the screen – is that what you really think is the basis for sea level measurements. Golly gee we are dealing with a big dope aren’t we.
And the classic – no greenhouse effect under clouds. Woo hoo !
No wonder they use you as an advocate. The ability to talk utter crap and not blink.
Pull up the anchor boys we’ve got a big marlin hooked here.
Could someone explain to Luke that a layer of land based ice 1.5km thick will need a sea level rise of 1.35km (90%) before the ice floats. So the scarenario of the sea getting under the Greenland ice sheet, any time soon, even the parts slightly below current sea level, is pure delusion. But gee wiz, it was in the National Geographic so it must have been right.
Historical sea level measurements were based on fixed measuring points, get used to it. But Luke’s willingness to bend the facts for the sake of a put down highlights the extent to which he is acting in other than good faith.
And once again we have this old chestnut about the glaciers. Note that Luke gave snippets of factoids like a particular glacier sheds 11cubic miles/year but he conspicuously failed to give a total, in Km3, that could be compared with the total annual layering.
For the record, according to http://news.nationalgeographic.com/news/2006/09/060920-greenland-ice.html latest estimates are 248km3 or less than what is being laid down each year. But neither National Geographic nor Luke would bother providing the missing information.
And this link to NASA (where else) provides a good example of the kind of spin being dished up.
http://earthobservatory.nasa.gov/Study/vanishing/
Note the graphics refer only to “ice melt” not the proper term “surface melting”. The former conveys a sense that the whole portion of the sheet has melted which is not the case. The pink parts merely show the part of the still very present ice sheet where puddles of surface melt water hung around for a few months before being frozen again. And as annual layering is in the order of 23cm we can safely assume that very little of the surface melt water escapes to the sea. Note also the 2000m contour which makes it clear that sea level would actually need to rise by 1800 metres before the sheet will float.
Note also the reference to the fact that glaciers are only speeding up in the southern portion.
Luke said, “At the margins warmer currents eat away at the grounding line”. Really, most of Greenland is well above sea level so any currents eating away at the grounding line are isolated incidents. Ditto for Antarctica.
Ian – “I see your point, Ender, but it is wrong to be using 60N as the example. The current northern boundary of summer pack ice is 80N and that, or higher, defines the angles of relevance to Hansen’s scarenario. The Noon angles at 80N are;”
Thanks for that however as noted before even at these low angles the rough and/or wavy sea will drastically reduce the albedo of the sea as it will not reflect anything like the amount of radiation that you think it will from reading off the graph.
As to clouds the present measured albedo of the polar regions takes into account the cloud cover which to my knowledge has not changed. So for the times when there are reasonably clear skies in these polar region (anything under 6 octas or so) the fact that there is less ice will result, when averaged over a time period, in a net reduction of radiation reflected to space from the ice.
To say that cloud cover negates the loss of ice is in my opinion wrong as the total yearly radiation budget of the polar regions includes reflection from clouds. If the average amount of clouds stays much the same then the only thing that is changing is the amount of ice. This will result in a change in the energy budget resulting in more radiation being absorbed by the ocean/atmosphere system.
Contrary to what you say I do not think low sun angle reflection makes up for the loss of ice cover as the sea is very rarely in a state where the low angle reflection will increase the albedo of the sea to anywhere like that of ice. As other people have pointed out quite small changes in the heat budget of these regions can result in large changes in the climate as already is evidence by species movement, loss of permafrost and the lowest level of summer sea ice for many years. Measurements from nuclear submarines of the last 40 years also confirm that the ice cap is thinning substantially.
Perhaps Hansen is being alarmist however it is wrong to dismiss his conclusions just because of personalities. Also there is the small chance that he might be correct – you cannot possibly say with 100% certainty that he is wrong because the same uncertainly about the science of climate in polar regions constrains you in exactly the same way. If you are genuinely aware of the uncertainties you cannot conclude with 100% certainty that you are correct.
Missed the point – JEEZ – see slipping and calving not melting.
Ian you have a wondeful technique (obviously learned as an advocate) of projecting single examples to the general. Doesn’t wash with me boyo. So you’ve stupidly rearranged the whole point.
See GRACE experiments for Greenland mass balance. Scientists referenced in the Nat Geo story were essentially those in the Science papers I referenced months ago. There not flakes.
I didn’t say all of Greenland was below sea level.
The issue is that is there enough evidence to suggest the ice sheet instability is an issue. It’s about risk management. Clearly there is a concern about ice sheet stability as AGW chips away in a number of ways. Can a sudden flip happen. Well gee I don’t know. When – don’t know. But I would not have expected to see ice movements occurring this quickly in the 1980s and 1990s when some of us were thinking about this stuff before it became fashionable.
We seem to have activity levels outside our expectation. Melting of sea ice, speed up of glaciers.
The foul language that you’ve used against Hansen is a disgrace. Do you think these guys came down in the last shower. They’ve at the leading edge of their science in teams of talented people. You actually think they haven’t thought of sun angle, albedo and cloud cover. You’d have to have a massive ego. Which is obvious.
If you read his stuff carefully Hansen’s advocating solutions. And solutions involve remove CO2 from the atmosphere.
So what would you like to do Ian. Find out what happens? There’s a risk you are right and risk you are wrong.
ENDER – yep agree ! Small changes in heat budget are certainly having significant effects.
Ians problem is that he doesn’t seem to realise it, but he is constructing what are very simplistic models himself, while refusing to believe any part of the highly sophisticated models that appear to be substantially correct.
Let’s start by seeing what Hansen has said in interview.
http://www.abc.net.au/7.30/content/2007/s1870955.htm
Below sea level:
http://www.geocities.com/Yosemite/4466/mapintro.html
http://www.radix.net/~bobg/faqs/sea.level.faq.html
Stoat on Hansen
http://scienceblogs.com/stoat/2007/06/the_earth_today_stands_in_immi_1.php#more
Climatologists on Hansen
http://groups.google.com/group/globalchange/browse_thread/thread/b04b87673f856352
Ender, I have no problem with much of what you said. Yes, the portion of insolation that does get through the clouds will then have varying responses depending on whether it hits ice or water. I agree on wave action altering low angle charachteristics. But I also recall but don’t have the time to chase up, a link that outlined how these albedo values were assigned to the GCMs and it appeared to use the zenith value as the sole determinant of incidence angle.
And I note that you haven’t substantiated how long the high midday angles remain.
The issue is that the material presented by Hansen and all the media statements dealt only in the switch from ice to water. And this failure to mention the dominant cloud function served to grossly exaggerate the scale of the potential change. I have no doubt that the GCMs included cloud cover but when public statements are made that have such major omissions then I have no choice but to doubt any conclusions drawn from them.
In any event, the cloud cover data does not define what sort of cloud cover is present and as the variation in albedo from different kinds of cloud is almost as great as for different kinds of snow then it is quite clear that a single value for either in a GCM is fraught with error.
Hansen’s team at NASA have a record of excluding inconvenient variables and as the public statements have no mention of cloud altogether then one must conclude that the prospect that melted sea ice might actually increase the high albedo cumulostratus cloud cover has not been considered.
Hansen has tried to shape the debate in terms of major changes in albedo in a zone where the actual insolation values are very low. But the reality is that other variables like cloud composition, the freshness of snow cover, the angle of incidence at other than Noon times, potential increases in cloud and water vapour volume as a direct consequence of warmer water, are fully capable of retarding, if not negating, the adverse impact of the ice/water albedo change.
I note that you based your argument above on the assumption that cloud cover, and composition, was constant. This is unlikely to be the case. Take a look at the wikipedia graph of dew point, http://en.wikipedia.org/wiki/Dew_point and observe how an increase in temperature increases the capacity of air to hold moisture. And the only conclusion to be drawn from this is that the gaps in cloud cover over an altered ice/water landscape will allow localised warming which will increase the density of cloud cover which will then counter the localised albedo change.
This is especially relevant in relation to the large climatic inertia represented by the existing ice and permafrost volumes. This is the problem with Hansen’s scarenario. That ice mass is still there and it exerts a major influence in its own right. So while it is a cheap thrill to to speculate on the consequences of its absence, the simple facts are that it is very much present.
If someone can show me the sequence of events where a given incremental reduction in sea ice albedo will negate the inertia of the the Greenland ice sheet, the polar angles of incidence, and all the other variables then I will gladly assign a possibility of 0.05 that the Greenland ice sheet will melt away some time after the next 5000 years. At this stage Hansen’s gonzo projection of half gone in 200 years is about a 0.000001 probability.
And that is all from me. I am off to the farm before poor old Luke wants me to say 12 “Hail Hansens” for my disrespect for Dopi Wan.
Ian – “And I note that you haven’t substantiated how long the high midday angles remain.”
The midday angle the, the zenith angle lasts for 12:00 local noon. However similar angles last for 2 or 3 hours either side of local noon. In the case of summer they would persist from 1 hour after sunrise to 1 hour before sunset. It is not coincidence that the setting sun on a shimmering sea is just that – at sunset. I really do not know why I have to substantiate it as unless you live in a particularly deep cave I am sure that you can look at the window on a sunny day at various times of the year and make an educated guess at the path of the sun in these latitudes.
“The issue is that the material presented by Hansen and all the media statements dealt only in the switch from ice to water. And this failure to mention the dominant cloud function served to grossly exaggerate the scale of the potential change.”
That what you do not know. How did your GCM runs go? What research have you done to substantiate that statement that Hansen has grossly exaggerated the potential change. You can say it all you like and reason in the air however unless you have done some real research you do not this for a fact. Additionally all the research in the world will not let you be 100% certain that Hansen’s predictions are wrong. He could well be wrong due to the uncertainties in the science however as I said before the same uncertainties constrain your answers as well.
“If someone can show me the sequence of events where a given incremental reduction in sea ice albedo will negate the inertia of the the Greenland ice sheet, the polar angles of incidence, and all the other variables then I will gladly assign a possibility of 0.05 that the Greenland ice sheet will melt away some time after the next 5000 years. At this stage Hansen’s gonzo projection of half gone in 200 years is about a 0.000001 probability.”
I am sure if you were capable of setting up a GCM, which you might be – I don’t know, you would know the answers to these questions. The point is that Hansen et al have done EXACTLY that and your only response is “I don’t believe it”
So the upshot from your point of view is that you ask reasonable questions that are answered by the GCM runs which you then reply “well I don’t agree with the answers.” Which is fine but begs the question of why did you ask for this information in the first place if you are not going accept it anyway.
What you said, Ender, is wrong. “In the case of summer they would persist from 1 hour after sunrise to 1 hour before sunset”. This is not the case at the poles as the angle of incidence is influenced by the curve in two directions, not just one as is the case in the tropics.
And this means that the times when the sun is close to the zenith angle are a much smaller portion of the days sunshine. Take a flat plane, tilt it to 45 degrees and then rotate it by 45 degrees and the resulting angle of incidence is substantially less than 45 degrees.
The rest of your post was little more than casuistry which deserves to be noted but not responded to.
But it is worth repeating that the melting of sea ice will, when combined with temperature increase, produce an increase in the extent of cloud cover and the volume of moisture in those clouds. That will mean an increase in the albedo of those clouds. At the same time, the increased moisture will increase the volume and frequency of snow fall and this more frequent supply of fresh snow will increase the albedo of remaining land and ice mass.
The extent of this albedo increase is unknown but it has the potential to negate the warming and restore the sea icepack to the historical range of variation. This kind of feedback is likely to play a part in the well recognised cycles of ice expansion and decline. And it should be clearly noted that this historical range has only been slightly exceeded in recent times, if at all.
Ian – “And this means that the times when the sun is close to the zenith angle are a much smaller portion of the days sunshine. Take a flat plane, tilt it to 45 degrees and then rotate it by 45 degrees and the resulting angle of incidence is substantially less than 45 degrees.”
However we have established that the sea surface is very unlikely to be a polished mirror so the albedo will still not be near that of ice even if the sun angle is low. Quite apart from that the sun in summer even at high latitudes will be high enough for long enough – after all the ice does melt in summer so it must be doing something.
“But it is worth repeating that the melting of sea ice will, when combined with temperature increase, produce an increase in the extent of cloud cover and the volume of moisture in those clouds.”
Yes and that will increase the amount of re-radiated long wave radiation being trapped as clouds both reflect radiation and trap it. That is why the function of clouds is the least understood part of the GCMs. So your feedback effect can both increase and decrease the warming at the same time – which one will prevail?
Good points Ender, but angles will be low and your suggestion that these angles must be high enough to melt ice because it already does so, only applies to the latitudes in which this currently takes place. That condition becomes less and less true the further north one goes. One cannot apply the conditions at 60N to a situation at 80N and expect a proportionate response.
And as current cloud cover is in the 60% to 80% range then one must assume that increased cover and increased density of that cover will reduce the amount of heat getting through rather than increase the amount being trapped.
The maximum warming effect of clouds takes place when scattered clouds form over the oceans while adjacent land is clear. When these clouds build up and then move over the warmed land they then trap the heat and produce a net warming. This is not the general case in the Arctic where cloud cover remains high and reflects heat before it can be trapped by either cloud or CO2.
I must say, as a layman, I’m thoroughly enjoying this debate, and even beginning to follow the technical aspects of it! Although my opinion is about as stable on this issue as a polonium teacup, I do take heart because of two factors:
1. the issue is far more complicated with far more factors whatever their relevance than is presented in the popular press (and it’s far easier to make highly dramatised predictions of imminent failure and take comfort in the ‘badness’ of mankind than to accept reasonable reassurances) – not that I’m dissing the presentation of it in the media or the ‘raising of awareness’ (probably the worst language anyone has used in this debate so far, so I apologise) of this issue
2. With this amount of willpower studying the difficulties and problems of this issue, I don’t see much difficulty in successfully addressing it one way or t’other. Naively optimistic? Possibly, but then I bet there were days when Noah’s wife said ‘Don’t worry, dear, the rain will end one day, and you’ll get the chance to own your own vineyard’ and he replied ‘Oh yeah? Like hell!’
Cheers, guys! Keep it up!
Fernsy