Green Myth-Busting: Greenland was Once Green
Greenland MYTH: When Eric the Red and his Viking buddies settled Greenland, it was a lush pastoral paradise fit for farming and raising animals.
Facts: As climate change skepticism has developed into a full-blown industry, a number of myths have filtered out about historical patterns of warming and cooling: just mention the “Little Ice Age” or the “Medieval Warm Period” to your favorite skeptic, and let ‘em go…
As a history buff, I always found today’s myth fascinating. As Coby Beck at Grist notes, Viking leader Eric the Red gave Greenland its name not because it was lush and green, but because he wanted folks back home to think it was:
Greenland was called Greenland by Erik the Red (was he red?), who was in exile and wanted to attract people to a new colony. He thought you should give a land a good name so people would want to go there! It likely was a bit warmer when he landed for the first time than it was when the last settlers starved due to a number of factors — climate change, or at least some bad weather, a major one.
But it was never lush, and their existence was always harsh and meager, especially due to the Viking’s disdain for other peoples and ways of living. They attempted to live a European lifestyle in an arctic climate, side by side with Inuit who easily outlasted them. They starved surrounded by oceans and yet never ate fish! (Note: this was not a typical European behavior, and is a bit of a mystery to this day.)
The issue here, of course, really isn’t Greenland’s name; it’s the idea of a Medieval Warm Period that skeptics claim was comparable to the present day in terms of the average temperature (or even warmer!). By extension, ice melts on Greenland aren’t that big a deal: it’s happened before.
Coby has thoughts on the Medieval Warm Period, and points to information from NOAA. RealClimate, the blog for anyone interested in hardcore climate science, also presents a number of reasons why the perception skeptics have about the Medieval Warm Period are likely incorrect.
Greenland wasn’t green in the tenth century… and we don’t want it to become green this century…
December 4th, 2007 at 6:01 pm
Max,
First, you claimed above that you were going to explain why the “double standard” argument I made is irrelevant, and then you went and proved that you do not understand what I’m talking about:
The double standard is how you’ve accepted the Zwally study, and yet dismissed the more comprehensive Thomas study based on what you considered to be insufficient data in the margins. However, the Zwally study only used ATM data from 1993 to 1999.
The IPCC cannot make a determination that matches every single study. The fact that the ESA study and the IPCC’s findings are different does not mean that the ESA study was “ignored”. What you’re not getting is that the IPCC fully considered the increased gains in the interior, found by Johannessen and others. However, when those are combined with the losses that occurred in the margins over the same period, the result is a net mass loss. Zwally finds a net gain, but only uses ATM data to 1999. Thomas and Box find substantial losses overall.
December 4th, 2007 at 6:07 pm
Hi Jason,
Our posts crossed, but I will still “humor” you.
In your latest post you have not shown me any evidence that my original statement is untrue that:
IPCC IGNORED PUBLISHED DATA THAT CONTRADICTED ITS CLAIM OF A NET LOSS IN THE GREENLAND ICE SHEET EQUIVALENT TO A SEA LEVEL RISE OF 0.21 MM/YEAR OVER THE PERIOD 1993-2003.
Here is my evidence for this statement:
The published data say net growth of GIS 1993-2003.
IPCC claims net loss 1993-2003.
Therefore IPCC did not accept the published data; instead, it ignored it(or rejected it, if you prefer).
Whether or not there are other published reports out there that say something else is irrelevant to our discussion. I am not claiming that IPCC ignored ALL published reports. I am only saying they ignored these specific reports that contradicted their claim.
So you see my evidence above.
Where is your evidence, Jason? I have not yet seen it.
Regards,
Max
December 4th, 2007 at 7:33 pm
Hi Reasic,
REUR December 4th, 2007 at 1:16 am
Ok, you agree basically that Johannessen showed something very new, but still dispute its significance, or that whatever is happening below 1500m is relatively unimportant.
I can understand your different perspective about elevations below 1500m, after all, that is not far short of half the maximum elevation of the islands ice. However, the near coastal regions, are complex in profile and inlets, and plunge rapidly, and perhaps you did not realize that the area below 1500m is relatively small. The NOAA 1988 Greenland topography I mention sometime back shows this rather well.
If you look at Table 1 in Johannessen et al 2005, concerning ice-sheet areas, (herewith in units of ‘a’):
(1) Area surveyed OK by ERS below 1500m = 155.1a.
I propose that this area represents something like 75% of the total GIS area below 1500m, or in other words, there would be another 25% that could not be measured. (To test that proposal for reasonableness, see Fig 1, and judge the white areas which are within the heavy black line delineating the edge of the GIS,)
(2) Area surveyed above 1500m = 1,225.7a, which represents 98-97% of the area free of adverse surface anomalies for ERS.
(3) From this, it would seem that about (155/3)a = 52a of GIS below 1500m could NOT be measured by ERS, and the 2 or 3 % above 1500m hardly matter, so the missing percentage may be of the order of 52/(1226 + 155)x100 = 3.7%……but let’s simplify this and call it say 10%
(4) If you look at Table 1 in Thomas et al 2006, the Johannessen NET rate of change over say ~90% of GIS was +54 units. In order that the rate of loss in the non-measurable area of ~10% would just BALANCE the NET gain of the 90% area, there would have to be a rate of change of +54 x -9, or -486units. However, this number is an ORDER of MAGNITUDE MORE than Thomson’s results. (There is a net mass gain)
Jason, can you now see that the Johannessen data is indeed a paradigm shift in knowledge?
Cheers, Black Wallaby
December 4th, 2007 at 8:04 pm
Hi Jason,
More double-talk and waffling from you (December 4, 6:01pm), but still no EVIDENCE.
You wrote: “First, you claimed above that you were going to explain why the “double standard” argument I made is irrelevant, and then you went and proved that you do not understand what I’m talking about.”
Jason, you are waffling. This is a totally meaningless sentence.
Then you wrote: “The double standard is how you’ve accepted the Zwally study, and yet dismissed the more comprehensive Thomas study based on what you considered to be insufficient data in the margins. However, the Zwally study only used ATM data from 1993 to 1999.”
Again, Jason, I only stated that IPCC ignored published data that contradicted it’s claims, not there are not other reports out there that IPCC did not ignore because they fit the party line. Did IPCC use a “double standard”, as you call it or did it simply “cherry pick” the reports it liked best and ignore the ones that directly contradict its claims?
Call it by any name you prefer, Jason
Although this is irrelevant to our discussion, I will still address your statement that the Thomas study is “more comprehensive” than those of Johannessen and Zwally.
The only data series that cover the entire period are that of Johannessen and (with the exception of the cold period between October 2002 and April 2003, which was somehow cut out of the record) that of Zwally.
Others cover shorter periods:
· ATM: 1994-1999 and 1998-2004 (part of period only)
· ATM/ICESat: 1999-2005 (part of period only)
· Mass-budget: partial years 1996, 2001, 2005 (totally irrelevant to our discussion)
· GRACE: 2003-2005 (totally irrelevant to our discussion)
The ERS numbers show +64 mm/year above 1500m and –20 mm/year below 1500m (Johannessen), which Zwally has recalculated (by truncating the period by one colder half year and adding ATM/ICESat numbers plus “optimum interpretation” for the marginal areas, which could not be measured by ERS), but still coming up with a NET GAIN OVER THE ENTIRE ICE SHEET despite these differences, to quote: “The Greenland Ice Sheet is thinning at the margins (-42 +/- 2 Gt/a below the equilibrium-line altitude (ELA)) and growing inland (+53 +/- 2 Gt/a above the ELA) with a small overall mass gain (+11 +/- 3 Gt/a; -0.03 mm/a SLE (sea-level equivalent).
Here are some basic problems with Thomas’ cobbled-together ATM and ATM/ICESat records. First of all, they miss a significant part at the front end of the Johannessen time period entirely, so they do not provide a direct comparison of what happened over the entire period. They show major differences at both higher and lower elevations. Johannessen shows net growth >1500m (~70% of the GIS surface area) of 6.4 cm/year while Thomas, with his far less comprehensive cobbled-together ATM (1994-99 and 1997-2003) and ATM/ICESat (1999-2003) records, shows a growth >1500m of only 1.2 cm/year. Which one do you think is closer to the truth, Jason? The description of how this was all pieced together does not inspire great confidence in the accuracy of the conclusion reached. Where ERS data are available they are clearly more comprehensive than ATM data, not to mention spot studies using the mass-budget approach, which (as Thomas says) report small differences between very large numbers and are therefore too inaccurate or subjective to be of much value.
There is no reason to assume that this cobbled-together record based on a more sketchy and less comprehensive type of measurement than satellite altimetry (with exception of marginal areas) that also misses a significant period up front will give a more representative figure than Zwally’s “re-work” (enhancement/enlargement) of the Johannessen study (even though it chopped off 6 months of colder season at the end and, as a result, by definition understates the net mass gain over the period).
To your ridiculous statement: “So, as I’ve previously pointed out, your assertion that the Zwally study contains a more comprehensive set of ATM data is not true.” Jason, I never said it contained “a more comprehensive set of ATM data” (you made that one up), but I did say that with the tens of millions of data points from ERS it contained a more comprehensive set of data points.
But all this is really outside our discussion, anyway, Jason.
I DID NOT claim that IPCC ignored ALL reports (especially those that supported its desired message or paradigm of “net GIS ice loss resulting from AGW”, such as the Thomas report, which it embraced enthusiastically, I am sure).
I just brought you the EVIDENCE that:
IPCC IGNORED PUBLISHED DATA THAT CONTRADICTED ITS CLAIM OF ICE LOSS IN THE GREENLAND ICE SHEET EQUAL TO A SEA LEVEL RISE OF 0.21 MM/YR OVER THE PERIOD 1993-2003.
This is what the record shows, Jason. IPCC “cherry picked” the reports they liked and IGNORED the ones they did not like (Johannessen and Zwally).
And unless you are able to show evidence that this statement is untrue, YOU HAVE LOST THIS POINT IN OUR DEBATE.
Now, before you shoot off another wordy but irrelevant post, do yourself a favor this time, as I asked you to do earlier:
Check Black Wallaby November 28, 2:47pm and my November 30, 8:29am for definitions of the words: IGNORE, CONSIDER, MENTION, ACCEPT and REJECT. This will help you stay on the subject and not digress.
Come with EVIDENCE, Jason, or concede that you have lost this point.
Regards,
Max
December 4th, 2007 at 10:15 pm
Reasic REUR December 4th, 2007 at 1:09 pm
YOU ASKED: I was just reading over your response above, and had one quick question for you about it: [concerning]:
“…The most important results obtained in Johannessen et al 2005, were that the ice-sheet above 1500m, had shown SUBSTANTIAL GROWTH, but with HIGH INTER-ANNUAL VARIABILITY, and it was INFLUENCED by the NAO cycle…”
Could you clarify for me what your purpose in bringing up the NAO is?
__________________________________________
My following paragraph gave a part explanation:
“Previously, some very scant aerial surveys suggested near balance or loss, NOT substantial growth. Furthermore, THE VARIABILITY was so strong that MEANINGFUL LONG TERM TRENDS could not be determined, even over a continuous 11-year cycle!”
Expanding on that we can say:
• The NAO cycle explains part of the high inter-annual variability in ice sheet growth
• It has been around since long before anyone even thought about CO2
• Sporadic measurements of ice sheet growth, say in May-June in 1993 in about half of the island don’t mean much in terms of trend, when there is high inter-annual variability.
Cheers, Black Wallaby
December 5th, 2007 at 2:42 pm
Bob,
WHAT?!?! Are you crazy?! You propose, and then test for “reasonableness” by looking at a small map with your naked eye?! Let me do my own reasonableness test for you:
Total area of GIS = 1,833,900 sq km (from Max)
Total area of ERS study = 1,380,700 sq km
Total area of ERS study below 1500m = 155,100 sq km
Total area of ERS study above 1500m = 1,380,700 - 155,100 = 1,225,600 sq km
Total area of GIS above 1500m = 1,225,600 / 0.975 = 1,257,026 sq km
Total area of GIS below 1500m = 1,833,900 - 1,257,026 = 576,874 sq km
% of area below 1500m covered by ERS study = (155,100 / 576,874) x 100 = 26.9%
So no, the Johannessen study did not cover 75% of the GIS below 1500m.
This percentage was used in my calculation above to determine the total area of the GIS above 1500m from the total area surveyed above 1500m.
Where are you getting these numbers?! Let me help you again:
Total area of GIS = 1,833,900 sq km (from Max)
Total area of ERS study = 1,380,700 sq km
Total area not covered = 1,833,900 - 1,380,700 = 453,200 sq km
% not covered = (453,200 / 1,833,900) x 100 = 24.7%
But let’s simplify and call it say 25%.
Well, I’ve already shown that you have the percentages wrong, but there are some other considerations that you must take into account when performing this calculation. I’ll provide you with the numbers, and if you have any questions, feel free to look back to pages 34 and 35 for more explanation:
Volume of gains (above 1500 m elev.) = (64.4 cm / 100,000 cm/km) x 1,225,600 square km = 789.3 cubic km (snow)
Volume of losses (below 1500 m elev.) = (28 cm / 100,000 cm/km) x 155,100 square km = 43.4 cubic km (ice)
Convert gains to ice: 789.3 x (0.35 / 0.92) = 300.3 cubic km (ice)
Total gains = 300.3 - 43.4 = 256.9 cubic km (ice)
Surface of missing area = 1,833,900 - 1,380,700 = 453,200 square km
Loss needed in missing area = (256.9 cubic km x 100,000 cm/km) / 453,200 square km = 56.7 cm or 0.57 m
So, to achieve mass balance, a loss of 56.7 cm would be needed, which is obviously much less than your number.
No, your calculations were of no help. I will try to think about a better way to explain my point to you and Max and will respond when I figure that out.
December 5th, 2007 at 4:36 pm
Hi Jason,
Still waiting for your specific response.
Regards,
Max
December 5th, 2007 at 5:28 pm
Max,
Re: Thomas v. Zwally
Earlier in this same post, you quoted my statement on how the Zwally study only used ATM data from 1993 to 1999, and yet you’ve still made the argument that the Zwally study is more comprehensive than Thomas? I’m going to spell it out for you as clearly as I can. Please pay attention:
The Thomas study used ERS data combined with ATM/ICESat data from 1993 to 2004. The Zwally expanded ERS to cover more area than Johannessen, and then combined that with ATM data from only 1993 to 1999, and with interpolation. In addition, the Thomas study corrected for snow density, while the Zwally study used the density of ice everywhere. Here is the difference between the two studies as explained in the Thomas study:
In addition, the Zwally study does not cover the entire GIS. It covers the entire COTERMINOUS ice sheet, which means it still leaves out approximately 100,000 sq km, or more than 5% of the GIS.
Now, as to this argument’s relevance, it is directly related to an argument that you have continually made to me. I know you are not claiming that the IPCC has ignored ALL research, but whenever I point out to you that the Johannessen study does not cover the entire GIS, you are quick to point out that the Zwally study does, and that it also results in a net loss. So, accpeting the Zwally study and also rejecting the Thomas study is part of your argument, which is why I’ve tried to point out that the Thomas study is an equal if not better indicator of mass balance over the entire GIS.
December 5th, 2007 at 5:30 pm
Max,
I’m getting there. I just needed to address Bob’s erroneous calculations, and the double standard issue one last time. I hope to give you a specific response later today.
December 5th, 2007 at 7:56 pm
Hi Jason,
Please excuse me for cutting into your exchange with Black Wallaby, but I would just like to correct a couple of errors in your calculation, starting with “Volume of gains (above 1500m elev)…”
You wrote me: “I just needed to address Bob’s erroneous calculations”, so let me, address your erroneous calculation in your message to Bob:
If you go through Johannessen’s numbers very carefully, you will see that:
· volume of gains >1500m should be 855 cubic km (not 789.3)
· volume of loss >1500m should be 34 cubic km (not 43.4)
Converting for density difference the net gain is 291 cubic km (not 256.9)
· loss needed in missing area TO ACHIEVE ZERO GAIN should be 64.3 cm (not 56.7)
Admittedly, this is not much different from what you calculated.
But, as Zwally points out, you cannot just calculate an average density of snowpack at 0.35 for gains and compare this with ice at a density of 0.92 for losses in order to arrive at mass balance figures.
To quote from his study: “For the first time, we use a firn compaction model with a 20-year record of satellite-based surface temperatures to calculate corrections for elevation changes due to changes in the rate of firm compaction caused by temporal variations in firn temperature and near-surface melting.”
“Near-surface melting and subsequent refreezing in the firn also lowers the surface by changing firn to higher-density ice, which in turn affects the rate of subsequent densification.”
“The average dC/dt over the accumulation zone is 1.71 cm/a, indicating an average surface lowering from increased rate of compaction. Without adjustment for dC/dt, this surface lowering might be incorrectly interpreted as a mass loss of 23.4 Gt/a (using an average column density of 0.9).” [In other words, figuring it the way you did would give an incorrect interpretation of loss.]
Without applying Zwally’s correction, mass losses (measured as ice at a density of 0.92) are overstated while mass gains (calculated as snow pack at a density of 0.35) are understated, and the net negative mass balance difference between the two is exaggerated even further. Zwally then goes on to show how mass changes can be estimated taking this factor into account.
He states that the density factor “can range from 0.33 to 1 if the rate of firn compaction is not in steady state with the surface mass input”. This means that the effective density of the snow pack layer can vary from around 0.33 to 0.92 depending on the degree of firn compaction.
In the Zwally study this corrects an apparent mass loss of 42 Gt/year (using the 0.35 and 0.92 average densities for snow pack gain and ice loss, respectively) to a corrected net gain of 11 Gt/year, after applying this correction.
So the 855 cubic km of snow pack gain >1500m would, in fact, represent a larger equivalent volume of ice than 291 cubic km, and net losses <1500m required to achieve net balance would be considerably higher than the calculated 64.4 cm.
BUT, Jason, we are not talking about achieving ZERO GAIN but about the IPCC claim that the GIS LOST MASS equivalent to a sea level rise of 0.21 mm/year
At an ocean surface area of 363 million square km this is equal to 842 cubic km of water over the 11-year period.
This requires the melting of 915 cubic km of ice.
So, before applying Zwally’s correction for firn compaction, a total of 915 + 291 = 1206 cubic km of ice would need to melt. (An even larger cubic km of compacted snow pack would need to melt, as the Zwally study points out.)
This means a loss as averaged over THE ENTIRE MARGINAL AREA
of 266 cm or 11 times the loss rate measured by Johannessen <1500m, without even adjusting this number for Zwally’s firn compaction effect.
Whether this adjustment would make it 20 times or 50 times Johannessen’s measured loss rate <1500m is actually a moot point, but I think the above points out that the Johannessen conclusions and the IPCC claim are mutually exclusive, i.e. if you accept one you must reject the other.
Hope this helps clear up some confusion.
Regards,
Max