By Steve Goddard, as a follow up to this story
‘http://en.wikipedia.org/wiki/File:Jakobshavn_retreat-1851-2006.jpg
The press has been getting worked up about a 7 km² chunk of ice which broke off the Jakobshavn (Greenland) glacier on July 6. Is this an unusual event?
Since 1831, the glacier has retreated about 60km, as seen in the image above. About half of that occurred in the first 80 years (prior to 1931) and the other half has occurred in the last 80 years. The long term rate has not changed. As you can see, the retreat occurs in spurts, with quiesced periods in between.
We keep hearing over and over again theories about huge recent increases in melt from Greenland and Antarctica, supposedly based on GRACE gravity anomaly data. If this were actually happening, sea level rise would absolutely have to accelerate to match. Where else can the melted ice go, but to the sea?
But sea level rise rates have generally declined since 2006, with the exception of the El Niño spike.
http://sealevel.colorado.edu/current/sl_noib_global_sm.jpg
The sea level data unequivocally shows that accelerated melt is not happening.
Now, let’s look at the size of the chunk which broke off from Jakobshavn – in green.
That represents 0.0003% of the Greenland ice sheet in area, and a much smaller percentage of the volume, which is 2,800,000,000,000 cubic metres.
A huge chunk of glacial ice sunk the Titanic almost 100 years ago. Where did that chunk come from? Enough alarmism, please.
In order to interpret gravity data, you need to have bedrock reference points below the ice. This is an impossible task for several reasons.
1. Any place where the ice is deep is, by definition, buried in ice.
2. There is almost no bedrock exposed in the interior of Greenland, as seen in the satellite image below. The few places where you can find bedrock are mountain tops, which exhibit very different isostatic behaviour than the valleys which are – buried in ice.
Conclusion – the interpretations of gravity anomaly data are flawed.
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DirkH says:
July 13, 2010 at 2:52 pm
richard telford says:
July 13, 2010 at 2:31 pm
“[…]We are now at a moment in history where we have the option to do something to safeguard our future.[…]”
That’s a meaningless sentence, think about it.
KD: I couldn’t agree more. How is it that anyone really believes we have the option to “do something to safeguard our future”.
It seems so mind-blowingly naive to think changing our emissions can have an impact significant enough to prevent ice-sheets from melting that HISTORY HAS SHOWN HAVE MELTED WITHOUT THE PRESENCE OF HUMAN EMISSIONS.
It strikes me as identical to those who choose to build/live in floodplains… exactly how’s that working for you?
KD
ps – for the record, I live on top of a hill in Wisconsin that is part of a glacial terminal moraine. I KNOW that means my land was once under a glacier. That’s the bad news. The good news is, given the speed with which glaciers tend to move, I think I’ll see it coming this time!
DirkH:
July 13, 2010 at 2:50 pm
Sorry, but that only counts for floating ice. If you put an ice cube in a glass and fill it to the rim, even when the icecube melts it will not flow over the edge.
Greenland, as the name states is ice on land.
“I also don’t believe in the second law of thermodynamics. I mean, just watch how life contradicts it.”
Your confusion is result of calculating the change in entropy of a system and ignoring the entropy change of the surroundings.
For instance, life decays rapidly when placed in a vacuum.
If you can find a verifiable event which violates the 2nd law, you will not only become famous, you will become wealthy beyond your wildest dreams.
stevengoddard says:
July 13, 2010 at 1:33 pm
EFS_Junior
How is your fastest Arctic ice melt on record coming along?
_________________________________________
Also known as a straw man.
How’s your Arctic sea ice extent increasing by 50K/year coming along?
ROTFLMFAO!
I am sure DirkH is correct concerning the floating ice cube , though has he not dropped a rather important “not” in his reply ….either that or I am really confused . I wont argue with Archimedes, but I was not fretting about the density or the mass which assuredly does not change,but I am still not smart enough to understand.Think of an iceberg recently calved, from a glacier, floating in the ocean. As water drips off it surface to add to the volume of the Arctic ocean and thus contributes to rising ocean levels, that water as it hits the ocean is presumably at or very close to zero degrees as it has only just melted.From that moment until it reaches 4 degrees does it not shrink? And all the other drops of water that fall into the ocean. The ice below the surface will also shrink will it not, till it reaches 4 degrees? It seems to me that the total volume of the newly calved iceberg plus the water that results from its melting will not cause the ocean level to rise until they reach 4 degrees.I was thinking the reason ocean levels are reported to have not risen as much as expected might be because that wont happen till all the arctic ocean is above 4 degrees. Probably nonsense. Just a thought.
mjk
Some basic knowledge of calculus is need to understand the graph.
http://img709.imageshack.us/img709/8536/sealevelchange.gif
The graph shows rate of change vs time (i.e the first derivative dX/dt.) The slope of the graph is the second derivative (d2X/dt2.) The slope is negative, which means a downwards curvature and therefore a decreasing rate of melt over time.
Instead of telling me my analysis is flawed, perhaps take a first semester calculus class at your local community college.
@ur momisugly Steven Goddard & mjk
Gentleman, Lets not get ad hominem now.
Slapping each other around the ears with studies and facts is so much more usefull.
Much better for the discussion as well.
Please debate with fact instead of insults.
This is an impossible task for several reasons.
“This is an impossible task for several reasons” is global warming’s middle name. Or is “unprecedented” its middle name? Or is it “we must act now”? Or is it “rotted ice”? Or is it “consensus among scientists”?
Enough. I’m nauseated now, and bored.
KD says:
July 13, 2010 at 3:13 pm
richard telford – I don’t get it… if history shows us that the ice-sheet can be much reduced without AGW, then why, exactly, is it that we have the belief that stemming CO2 will prevent the ice-sheet from being much reduced again?
—————
During the Eemian, the Earth’s orbital configuration was different, with more solar radiation in high northern latitudes during summer. It was this extra radiative heating (together with positive feedbacks, e.g. albedo changes) that caused much of the GIS to melt. This is well understood, and won’t happen again for some time.
Now there are different processes causing temperature changes at high latitudes. Ones that we have the opportunity to minimise.
@ur momisugly Chris Korvin:
July 13, 2010 at 3:28 pm
“I was thinking the reason ocean levels are reported to have not risen as much as expected might be because that wont happen till all the arctic ocean is above 4 degrees. Probably nonsense. Just a thought.”
The highest density is at 4 C. From -X to 4 C. it will expand, from 4 -till X it will decrease in density. Everything above 4 C will give a lower level.
gravity smavity
Glaciers have always advanced and retreated:
Glaciers even advanced and retreated during the very cold Younger Dryas. It always happens. It would be unprecedented if they didn’t advance and retreat.
Pardon my bafflement, but, concerning the opening overhead image of the glacier, when was there high altitude arctic photography in the early 19th century? How is it possible to show continuous glacier through the 1851 contour and earlier? Or is this the miracle of Photoshop?
As to the comparison of GRACE with GPS, I would hesitate to claim much for GPS. The accuracy of the system is worst in the vertical dimension, and can be as much as meters. But I do not automatically accept the interpretation of GRACE data as meaning Greenland icecap loss. Just because that interpretation is plausible does not mean it is correct. It requires confirmatory ground evidence.
And as for sea levels, I will propose this change of view: mean sea level is irrelevant; what is relevant is the high tide level. Has anyone followed the time history of high tide levels? Or the statistics of anomalous high tides? I walk on the beaches that I walked on as a boy, half a century ago, and they look the same.
steve goddard says, “The long term rate has not changed…the retreat occurs in spurts”
*************
While I agree the retreat has occurred in spurts from 1851 to 2001, it certainly appears that during the last decade, the Jakobshavn Glacier has lost at least 1/3 of the total 60 km.
You can sugar-coat it all you want, and even say the long-term rate has not changed, but when the glacier has retreated over 20 km of the entire 60 km retreat that started in 1831 just since 2001, it seems to me there is a huge question you have missed.
Just look at the years you have cataloged: 1851; 1875; 1883; 1902; 1913; 1929; 1931; 1953; 1964; and then a quick succession of years to the present: 2001; 2002; 2003; 2004; 2005; 2006; although we’re missing 2007-2010.
Hey, I could be wrong, but it seems you’ve missed a huge “what’s up with that,” point!
lakota2012
Many movements in nature occur in spurts. The San Andreas fault has not moved near Los Angeles for 250 years, but when it does – it will move a lot.
Stresses build up and then tend to get released quickly.
EFS_Junior
Back on the ignore list.
Whenever you have nothing intelligent to say, you just make up a random quote and attribute it to me.
Yes, of course consequences if the alarmists were able to return us to the Little Ice Age are irrelevant to them. In point of fact, that is not their aim at all. They would rather the glaciers melted, the seas rose, the land became a desert. That would ‘prove’ that their dire predictions were coming true, and they could then say, “We will be your saviors. Just do as we say, and follow our rule, and all will be well.”
/Mr Lynn
It’s asking a lot to expect people to believe any reports about glaciers with GlacierGate still fresh in their minds:
richard telford says:
July 13, 2010 at 3:50 pm
Now there are different processes causing temperature changes at high latitudes. Ones that we have the opportunity to minimise.
Warming at higher latitudes is not occurring the way global warming scenarios say it will. But you want the reader to infer it is.
So prove it.
Also prove your bizarre statement about changing weather.
I think it’s a little disingenuous to say phrase it like that. “Half the retreat occurred prior to 1931 with half of it since.” Actually, the vast majority of that second half has occurred in the last 9 years. The 1931-2000 period saw very little retreat. So, while it is accurate to say it occurs in spurts, this has been one hell of a spurt. Just admit that rather than glossing over the blatantly obvious. It makes you and everybody else look bad and puts you in the same camp as the alarmists who will completely ignore the dynamics that could have increased retreat since 2001 that likely have very little to do with CO2 warming.
steve, it’s not the “spurts” I’m questioning, but the rapid succession of those dramatic chunks lost from 2001 to the present, that appears to be more than 20 km of the entire 60 km loss from 1831. Looks like about 40 km was lost between 1831 and 2001 — a 170 year span — and then a whopping 20 km was lost from 2001 to the present or 9 years.
That seems to be cause for concern that you missed. “What’s up with that?”
“I don’t know which sea level rise rates you are looking at- but if they relate to the graph you posted, it is only going in one direction–”unequivocally” upwards. No reasonable person could look at the graph and think otherwise.”
And no-one is. Really you warmists really ought to read the other side’s positions before you start.
The CO2 theory is not that the earth is warming. We already know that. It is that warming is accelerating out of control due to GHG.
The constant rise in water level is a major issue for this theory, as it does not correlate to CO2 levels.
Melting glaciers are not an indication that the earth is warming. Only that the current temperatures are higher than keeps them at equilibrium.
Steve,
looking at the ‘calculus’ picture you embedded above, what are you referring to when you say ‘the slope is negative’?
Looking at the most recent data, the slope looks most definitely positive.
It may be that I am seriously confused on this matter and I think a more thorough explanation is in order.
Given I am also staring at a first principles calculation of the anti-symmetric portion of the molecular polarizability tensor, I think your poor explanation has little to do with who has or has not taken a calculus class at one’s local community college.
Moreover, there was a paper in Nature Geosciences a couple years back that pointed to the recent Jackobsianndaidnkkkkj glacial melt being due to fluctuations in the Gulf stream, causing warmer water to come in contact with the ice Greenland. Having spoken with a young glacialogist/hydrologist not too long ago, this seems like the most likely culprit for the recent retreat. According to this guy, fishing records also showed similar warm waters in the 1920’s and 1930’s, when there was a similar retreat of the glacier, as seen above.
Considering that, I think the real question is, why didn’t the glacier grow during the times when the Gulf Stream wasn’t sending warm water its way? Transients from the warm water are likely several years, if not decades, long, but it makes me wonder at least.
[snip OK this is just sniping – cut it out both of you – Anthony]
maxwell
The trend line (thick blue) slopes down towards the right. That is negative slope.
http://img709.imageshack.us/img709/8536/sealevelchange.gif