Finally some recognition of all the anecdotal weather we’ve been talking about here – Anthony
World Meteorological Organization
Thu Aug 21, 2008 1:15am IST
LONDON (Reuters) – The first half of 2008 was the coolest for at least five years, the World Meteorological Organisation (WMO) said on Wednesday.
The whole year will almost certainly be cooler than recent years, although temperatures remain above the historical average.
Global temperatures vary annually according to natural cycles. For example, they are driven by shifting ocean currents, and dips do not undermine the case that man-made greenhouse gas emissions are causing long-term global warming, climate scientists say.
Chillier weather this year is partly because of a global weather pattern called La Nina that follows a periodic warming effect called El Nino.
“We can expect with high probability this year will be cooler than the previous five years,” said Omar Baddour, responsible for climate data and monitoring at the WMO.
“Definitely the La Nina should have had an effect, how much we cannot say.”
“Up to July 2008, this year has been cooler than the previous five years at least. It still looks like it’s warmer than average,” added Baddour.
The global mean temperature to end-July was 0.28 degrees Celsius above the 1961-1990 average, the UK-based MetOffice Hadley Centre for climate change research said on Wednesday. That would make the first half of 2008 the coolest since 2000.
“Of course at the beginning of the year there was La Nina, and that would have had the effect of suppressing temperatures somewhat as well,” Met Office meteorologist John Hammond said.
“I thought oil was ancient marine animal given, not fictitious sky daddy given.” Jeff Alberts
Jeff,
We are allies here. Some of my arguments are to my coreligionists who have been hoodwinked into extreme environmentalism among other things. They are not directed at you. But I remind you that they too can vote. I know where you stand and would love to engage in hand-to-hand with you on the subject of “sky-daddy” but we must deal with the common enemy first.
Respectfully
There is an HTML-coding error in my previous post…Everything from “You have not kept up with their work…” on down (except the paragraph further indented) are my own words, not manacker’s.
“I wish your statement to be true – that we could use our God given resources without feeling guilty about hurting others (particularly the poor”
Our resources are helping the poor. If we stop using our resources, only God will be able to help the poor. The poor will suffer the most from any misguided UN policies that attempt to create a low carbon world.
I understand. I just think mentioning “god” significantly degrades any scientific discussion.
Jeff Alberts (15:51:15) : “I understand. I just think mentioning “god” significantly degrades any scientific discussion.”
Really? I think that is a very narrow interpretation. The phrase “God given” could mean many things; for many naturalists (like many Hindus and Buddists) nature itself is the god. Unless you want to take it in the religious way, it only means resources just given/available to us without us doing anything to make it. Take another example, is it true that the use of the phrase “acts of God” diminishes the value of legal contracts (particularly for insurance)? Yet it is very difficult to find an insurance contract without that phrase. Those words are perfectly well understood, unless someone wants to interpret it in a specific way.
Mike Bryant (12:58:01) : “Our resources are helping the poor. If we stop using our resources, only God will be able to help the poor. The poor will suffer the most from any misguided UN policies that attempt to create a low carbon world.”
That is the main issue here. Until there is enough scientific evidence to suggest that not using fossil fuel energy resources will harm the poor more than using these resources in the long run, I think we are morally obliged to restrain from using those potentially more harmful resources. I do not think there is enough scientific evidence to support that. If and when there is, I will be very happy to change my opinion.
John McLondon (18:03:16) :
And we all know how many Hindus and Buddhists are commenting here 😉 I don’t see any other way to take a mention of “god” other than religious. Even in the “naturalist” sense, it’s still a religious reference, something to be worshipped without evidence of existense or purpose.
Yes, using the phrase “act of God” in legal documents should be removed in favor of “Natural/Weather events.” Anything wrong with that? After all an “act of God” could mean literally anything to a religious person.
Can we just stop the religious discussion, or the attempts to interpret whether the mention of God automatically is a religious discussion?
Let’s just move on. Please everyone stop trying to get the last word on this subject. Hopefully, that will be my last word on the subject.
Mosher says I’m right so there.
jeez aka charles the moderator.
Hi Joel,
Thanks for your comments to my earlier post. Let’s clear up the points one by one.
“I’m not sure how you get 0.76°C. I get 0.98°C if I use your 3.67 W/m^2 value.”
It is not “my” 3.67 W/m^2 value. It is the value stated by IPCC AR4 WG1 (Chapter 10, p.758).
Now for the calculation (I actually used 3.708/m^2 based on Myhre et al):
At 2xCO2, C2/C1 = 2.0
ln2 = 0.6931
5.35*ln2 = 3.708
Greenhouse gases trap heat within the surface-troposphere system (the lower troposphere) 0-3000m.
Tsurface = 15.0°C
Using T at 1500m = Tsurface – 1.5 * 6.5 = 5.25°C = 278.41K
Stefan-Boltzman:
4*5.6705E-08*(278.41^3) = 4.895
dT = 3.708 / 4.895 = 0.76K = 0.76°C
Regarding the various feedbacks, you wrote: “Besides the quibble in regards to the doubling of CO2 alone, which I think should be at least 1.0°C, I think your numbers are basically correct here. (As you noted in regards to Hansen, I have seen others say 1.1 or 1.2 C although I am not sure how they get this.)”
You just wrote me that you calculated 0.98°C but that you think it “should be at least 1.0°C”. I cannot understand this statement. Is this really what you wanted to write?
I wonder how Hansen and “others” come up with 1.1 or 1.2°C, since it is a fairly straightforward calculation that does not require a multi-million dollar computer. You also say you are “not sure how they get this”. Guess we’ll have to leave it at that and assume that it’s just a bit of Hansen exaggeration to get his point across.
“However, there are some error bars on these numbers…in particular, the cloud feedback…which is why although the model average for total feedbacks may be +3.2°C, there is considerable spread amongst the model and the IPCC likely range is 2.0 to 4.5°C. [Which, I guess means they are saying that the cloud feedback is likely positive, but the range is from just about neutral to quite strongly positive.]”
Well, not really, Joel. They are not “saying that the cloud feedback is likely positive, but the range is from just about neutral to quite strongly positive”.
IPCC tells us “the GCMs all predict a positive cloud feedback (Figure 8.14) but strongly disagree on its magnitude”. (A glance at Figure 8.14 confirms this.)
The net impact of cloud feedbacks is to increase the 2xCO2 sensitivity including all feedbacks (excluding clouds) from 1.9°C ± 0.15°C to a value (including cloud feedback) of 3.2°C ± 0.7°C (i.e. a range of 2.5°C to 3.9°C).
This is a “whopping” increase from clouds of 1.3°C (i.e. a range of 0.8°C to 1.8°C)! To put this into perspective, the assumed cloud feedbacks alone double or triple the 2xCO2 warming from CO2 alone.
Nowhere is there anything even close to a “range from just about neutral to quite strongly positive”. IPCC assumes it’s “positive” all the way, Joel (as they also clearly state).
Now to your Minschwaner + Dessler “update”. There is nothing new here, Joel. Read what it says:
“Furthermore, the implied feedback in the models is not as strong as would be the case if relative humidity remained constant in the upper troposphere. The model mean decrease in relative humidity is −2.3% ± 1.0% K−1 at 250 mb, whereas observations indicate decreases of −4.8% ± 1.7% K−1 near 215 mb.”
Observations show a decrease in RH of –4.8% per degree K warming.
The M+D model calculated a decrease in RH of –2.3% per degree K warming.
Yet IPCC models assume a constant RH with warming.
These are pretty much the same figures M+D presented in their 2004 study, which I cited. (This is logical, because the later paper draws on exactly the same observations as the earlier paper.)
To quote from the earlier paper, which I cited:
“Rather than finding either a “constant relative humidity” or a “20% increase in specific humidity” as assumed by the IPCC GCMs, the M-D report concludes, “The increases in water vapor with warmer temperatures are not large enough to maintain a constant relative humidity”. “We find that relative humidity in the UT decreases with increasing surface temperature, on the order of 3%-5% per degree of surface warming.” [Note that this is the same conclusion drawn in the later paper.]
The results cited for specific humidity variations are (p.1279):
1.8 to 4.2 ppm/C with an average of 3 ppm/C (Minschwaner, observed data)
8.5 to 9.5 ppm/C (Minschwaner model)
This compares with:
20 ppm/C (climate models used by IPCC = constant relative humidity)
(M+D even put this into a nice graph; a picture is worth…)
This should answer your query, “I never understood how you came up with that factor of 5 anyway.” (Try dividing 20 by 1.8 and then by 4.2 and averaging the two results. You will actually come up with a mean value of close to 7. But I just stated a factor of 5.)
Yes, “within experimental and model uncertainties…the water vapor is behaving as expected” (i.e. water vapor content increases at temperature rises).
But it is the magnitude of this increase where the physically observed data and the IPCC assumptions disagree strongly: IPCC says “+20% specific humidity” and the satellites show “+3% ± 1.2%”.
And that was my point, Joel. The IPCC assumptions exaggerate the warming from water vaper feedback because they exaggerate the amount of atmospheric water vapor increase with increased tempedrature.
Regards,
Max
Max,
Most of what you wrote seems to be not worth quibbling over. E.g., your assumption that greenhouse gases absorb only in the lower levels (0-3000m) of the atmosphere is not very realistic…and since the radiative forcings are top-of-the-atmosphere numbers, your use of a temperature in that region is not correct. But whatever.
The more serious errors you make are when you discuss the paper by MINSCHWANER, DESSLER, and SAWAENGPHOKHAI (which is available in PDF form here: http://physics.nmt.edu/~krm/minschwaneretal_jcli2006.pdf ). For example, you say:
These statements (or at least 2 out of 3 of them) are incorrect. The models discussed in that paper are the models that the IPCC uses, not the M+D model. Hence the statement: “In this paper, we present an analysis of the water vapor feedback in the tropical upper troposphere as simulated by 17 coupled ocean–atmosphere climate models. The model simulations were performed in support of the Working Group One component of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. This multimodel output presents a unique opportunity for assessing the performance and sensitivity of the current generationof climate models.”
These models do not assume constant RH with warming. It has often been said that this seems to be an approximate result of the models but one important point of this paper is that in fact the models predict the RH values in the upper troposphere to drop somewhat with warming. It is true that the central estimate of the drop in RH is larger in the observations than the models but they are within error bars of each other.
Hi Joel,
You apparently feel that it may not be “worth quibbling over” the IPCC assumptions on 2xCO2 climate sensitivity, but it makes all the difference whether or not AGW is a real and present threat to our climate (as projected for the future) or a minor increase in global temperature (as actually observed so far).
The past observation (0.6°C to 0.7°C rise in temperature over the entire 20th century) is hard to reconcile with a 2xCO2 sensitivity of 3.2°C.
To start off, you apparently have a problem with a 2xCO2 calculation (without feedbacks), resulting in around 0.8°C. Please indicate how you would arrive at 1.0°C to 1.2°C.
As for the water vapor feedback itself. Regardless of how you try to rationalize it, Joel, the facts are the facts.
IPCC states repeatedly that the models it cites are based on the assumption that atmospheric water vapor concentrations will increase with increased temperature. No one disputes this.
The dispute comes in the AMOUNT of water vapor increase.
IPCC states (Chapter 3), “The global trends of near-surface relative humidity are very small. Trends in specific humidity tend to follow surface temperature trends with a global average increase of 0.06 g/kg per decade (1976-2004). The rise in specific humidity corresponds to about 4.9% per 1°C warming over the globe.”
Later on IPCC states, “Wang et al. (2001) found an increasing trend of 1 to 5% per decade in relative humidity during 1976 to 1995, with the largest increases in the upper troposphere, using 17 radiosonde stations in the tropical west Pacific. Conversely, a combination of Microwave Limb Sounder (MLS) and Halogen Occultation Equipment (HALOE) measurements at 215 hPa suggested increases in water vapour with increasing temperature (Minschwaner and Dessler, 2004) on interannual time scales, but at a rate smaller than expected from constant relative humidity.”
The reason for this discrepancy, “Comparisons of water vapour sensors during recent intensive field campaigns have produced a renewed appreciation of random and systematic errors in radiosonde measurements of upper-troposheric water vapour`and of the difficulty in developing accurate corrections for these measurements.”
Let’s boil all this down to a few words: Earlier radiosonde measurements (Wang) pointed to an increase in relative humidity with warming. These conclusions were subsequently shown to be erroneous (M+D), and the relative humidity was observed to decrease with warming. Later studies revealed the root cause for the early radiosonde errors.
In Chapter 8, IPCC gets more specific on humidity and water vapor feedback assumptions for the models.
“Calculations with GCMs suggest that water vapour remains at an approximately constant fraction of its saturated value (close to unchanged relative humidity (RH)) under global-scale warming.” “Variations in upper-tropospheric water vapour have been observed across time scales from seasonal and interannual to decadal as well as in response to external forcing. At tropics-wide scales, they correspond to roughly unchanged RH and GCMs are generally able to reproduce these observed variations.” “ New evidence from both observations and models has reinforced the conventional view of a roughly unchanged RH in response to warming.”
In other words, we are told repeatedly that IPCC GCMs go along with the “conventional view” of constant RH with warming, despite the fact that the M+D satellite observations cited previously showed a reduction in RH with warming.
In Chapter 10, IPCC tells us that the CGM outputs show, “In response to a doubling in atmospheric CO2, the specific humidity increases by approximately 20% through much of the troposphere.”
This can only be achieved under the assumption of contant (to slighly increasing) RH. If, however, RH decreases with rising temperature as measured by the satellites, this assumption is incorrect and will give an exaggerated water vapor feedback.
That’s the whole point here, Joel.
We are not “quibbling” about moisture increase with warming, just about the magnitude of this increase, where we have IPCC models assuming a major increase and the facts on the ground (or actually in the sky) showing us a much more modest increase. I showed you previously the extent of this discrepancy, but will only repeat the slightly revised findings of the later M+D study (plus the assumption of IPCC models):
– M+D satellite observations show a decrease in RH of –4.8% per degree K warming
– The M+D model calculated a decrease in RH of –2.3% per degree K warming
– IPCC models assume a constant RH with warming
M+D put this into a nice graph that makes the discrepancy quite easy to see.
It is the same problem IPCC has with assumed positive cloud feedbacks. Models assume one thing (strong positive feedback) and physical observations show another (strong negative feedback).
It is a systematic error of IPCC models. They are programmed with assumed parameters that result in exaggerated forecasts (or projections) of warming with increased CO2.
These are some of the reasons why the 3.2°C ± 0.7°C (i.e. 2.5°C to 3.9°C) climate sensitivity for 2xCO2 as stated by IPCC is likely to be a three to four-fold exaggeration, and the real value should be around 0.7°C to 0.8°C, as estimated by scientists such as Lindzen and Shaviv + Veizer.
But we may have to just “agree to disagree” on this one, if you are unwilling to accept the facts as they are.
Regards,
Max
I think the reason why we may have to agree to disagree is because you are confused about what the facts are. You repeat the incorrect statements above even though I told you that they are incorrect. Only the first of your statements is correct (and even then, without error bars to put it in context). The other two statements are WRONG. M+D’s model does not predict a decrease in RH of –2.3% per degree K warming. Rather (if you look at the conclusions in their earlier paper), it predicts the “decrease in relative humidity at 215 mb is between -4.0% and -8.4% RHi /K”. The -2.3% +- 1.0% per degrees K at 250mb is the result from 17 coupled ocean–atmosphere global climate models…The same models that the IPCC uses. Hence, the IPCC models do not predict precisely that relative humidity is constant at that level in the atmosphere. (It is often said that they approximately predict this…and the approximation may well be better lower in the atmosphere…but it is not a precise statement of what they predict.
As for whether the water vapor feedback is overestimated, there is work by Soden and others that suggests that it is gotten about right.
It is not hard to reconcile at all. Arthur Smith has a nice plot in his response to Monckton’s “paper” in which he shows that the rise over the last 150 years is best fit by a TRANSIENT climate response of about 2 C per so per doubling. The equilibrium climate sensitivity is then expected to be a fair bit larger than that transient response.
The full truth of the matter is, however, that the data from the last 150 years does not provide very good constraints on climate sensitivity, since there are too many uncertainties associated with other forcings (especially aerosols). Better constraints are provided by looking at volcanic eruptions like Mt. Pinatubo and paleoclimate events, such as the last glacial maximum (or, best yet, combining everything together) and these point to a climate sensitivity in the range claimed by the IPCC. In fact, your estimate for climate sensitivity would necessitate a significant change in understanding past climate events such as the glacial – interglacial cycles.
There are good reasons why the IPCC has arrived at the estimates of the climate sensitivity that it has and why only a few scientists like Lindzen, Shaviv + Veizer, and Spencer (and non-scientists like Monckton) have persisted in arguing that the climate sensitivity is significantly lower.
Sorry, Joel, you are missing the facts. By just repeating the same stuff it doesn’t become more valid.
The facts are: IPCC models assume a contant RH with increasing temperature while satellite observations show a significant reduction in RH. M+D showed this in a very neat graph, showing the range of the satellite observations, the somewhat higher amount as predicted by their model and the significantly higher “constant RH” curve (as assumed by IPCC models).
Big difference, Joel, as I pointed out to you earlier.
This plus the cloud problem (as pointed out by Spencer) raises doubt on the 3.2K sensitivity of the IPCC GCMs.
Regards,
Max
Hi Joel,
Just to come back to your observation, “There are good reasons why the IPCC has arrived at the estimates of the climate sensitivity that it has and why only a few scientists like Lindzen, Shaviv + Veizer, and Spencer (and non-scientists like Monckton) have persisted in arguing that the climate sensitivity is significantly lower.”
Yes. I believe I can guess what these “good reasons” are.
They are probably the same “good reasons” why IPCC has ignored published studies that contradict the message of potentially alarming AGW (of which there are several examples).
They may also be the same “good reasons” why there are obvious exaggerations and flights of fancy in some of the IPCC projections.
But I believe we are not getting any further in this discussion, since you appear to be unwilling to see studies based on physical observations (such as M+D and Spencer) that do not fit into your AGW paradigm.
Regards,
Max
Jeff Alberts – And we all know how many Hindus and Buddhists are commenting here 😉
Yes, we are here.
manacker says:
The reason we are not getting any further is that you keep clinging to statements that are simply wrong like, “IPCC models assume a contant RH with increasing temperature.” They do not make any assumptions of this sort. To the extent that they predict something close to a constant RH, it is an output of the models, not an input. And, in fact, as the paper that I have linked to argues, their tests of 17 of the climate models discussed by the IPCC (which is most of them, I believe) predicts a decrease in RH at 250 mb.
By the way, I should have explicitly addressed your statement “you appear to be unwilling to see studies based on physical observations (such as M+D and Spencer) that do not fit into your AGW paradigm.”
The fact is that you distort the work of Dessler et al. to fit your paradigm. First, you seems to believe the observations to an accuracy that the authors themselves do not…and (along with ignoring their conclusions regarding the climate models in their later paper)…you then use their study to reach a conclusion very different than they did since their conclusion that “these two values [the observational one and the model prediction] agree within the respective ranges of uncertainty, indicating that current global climate models are simulating the observed behavior of water vapor in the tropical upper troposphere with reasonable accuracy” goes against your beliefs.
Max, “They are probably the same “good reasons” why IPCC has ignored published studies that contradict the message of potentially alarming AGW (of which there are several examples).”
Can you please give references for these published studies? I would like to read it, if I haven’t already read it. Thanks.
Note to John McLondon
Hi John,
Regarding studies ignored by IPCC, you wrote: “Can you please give references for these published studies? I would like to read it, if I haven’t already read it. Thanks.”
There are several, as I mentioned to Joel, so I’ll feed them to you in installments.
I’ll start of with the IPCC 2007 SPM and list examples of reports where the conclusions were either ignored, rejected or not accepted as correct by IPCC:
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
1. IPCC claims a net mass loss of Antarctic ice 1993-2003 due to anthropogenic global warming (AGW) with a corresponding rise in sea level over the same period (pp.5,7). The record based on 11 years of continuous actual measurements covering the same period shows no shrinking, but an increase with a corresponding lowering of sea level over the period.
http://bowfell.geol.ucl.ac.uk/~lidunka/EPSS-papers/djw3.pdf
2. IPCC claims a net mass loss of Greenland ice 1993-2003 due to AGW with a corresponding rise in sea level over the same period (pp.5,7). The record based on 11 years of continuous actual measurements covering the same period shows no shrinking, but an increase with a corresponding lowering of sea level over the period.
http://www.eurekalert.org/pub_releases/2005-11/esa-eas110405.php
http://www.sciencemag.org/cgi/content/abstract/1115356v1
http://www.igsoc.org/news/pressreleases/Zwally509.pdf
3. IPCC claims a reduction in Northern Hemisphere snow cover in the latter part of the 20th century due to AGW (pp.5,6). The actual record shows no such reduction since 1988. http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=nhland
I’ll come back with more later, but you may wish to review the above reports first.
Regards,
Max
Hi Joel,
All your fine words and rationalizations do not change the facts.
M+D satellite observations show significatly less water vapor increase with temperature (significant reduction in relative humidity) than is assumed in the climate modes cited by IPCC (essentially no change in relative humidity).
Facts are facts, Joel.
Regards,
Max
“Facts are facts…” Max
Couldn’t resist.
Hi Joel,
It is clear to me that we have concluded our discussion on the 3.2°C ± 0.7°C (2xCO2) climate sensitivity with feedbacks as assumed by IPCC models.
You believe it is reasonable.
I do not.
I have stated my reasons for my conclusion that it is an exaggeration:
1. The physical observations by Spencer et al on clouds which shows a strong net negative feedback, rather than a strong net positive feedback, as assumed in the GCMs cited by IPCC
2. The physical observations by Minschwaner + Dessler on water vapor, which show less water vapor increase with warming, therefore a smaller positive feedback from water vapor than assumed in the GCMs cited by IPCC
3. The observed temperature record since 1850, which shows multi-decadal oscillations and an underlying upward trend of 0.5°C per century, with no apparent correlation with atmospheric CO2 (except for the brief period 1976-1998)
IPCC relies too heavily on GCM assumptions and outputs, occasionally ignoring physical observations; it understates the impact of natural factors and exaggerates those from AGW.
For an excellent treatise on the key weakness in the IPCC view on AGW and its impact on climate change, I can recommend this study:
http://people.iarc.uaf.edu/~sakasofu/pdf/Earth_recovering_from_LIA_R.pdf
I would say that this study covers the topic more succinctly and thoroughly in 47 pages than AR4 does in 1000.
Regards,
Max
Pradad Ramaprasad (20:54:40) wrote to Jeff Alberts
“Jeff Alberts – And we all know how many Hindus and Buddhists are commenting here 😉
Yes, we are here.”
Pradad, That was a really bad comment from Jeff Alberts. I know many Hindus and Buddhists reading this blog. May be we should write more. There are almost 2 billion Hindus and Buddhists. To make us look small and make fun of us was very bad.
Max,
Thanks for the references.
This link is not there: http://bowfell.geol.ucl.ac.uk/~lidunka/EPSS-papers/djw3.pdf
This seems like a blog article, can you point me to a published journal paper instead
http://www.eurekalert.org/pub_releases/2005-11/esa-eas110405.php
On http://www.sciencemag.org/cgi/content/abstract/1115356v1 There are a large number of recent papers that counter your conclusion (many of them cite this paper) [note statements like “data show that Antarctica and Greenland are each losing mass overall” in these recent papers] using new techniques to distinguish between “melt” area and “dry” area. I am attaching a short list. To save space I am only posting two abstracts to give the thrust. I hope you can find the full articles to read. Greenland is losing ice mass – the middle thickness is probably increasing due to snowfall. But the overall picture is contrary to what you are suggesting. Even if we assume (against what is happening) that the ice mass is expanding now (due to increased precipitation), it does not really mean much, as we see that it was a temporary dynamic equilibrium stated in almost every paper (including the papers you suggested eg. http://www.igsoc.org/news/pressreleases/Zwally509.pdf in the “conclusion” section we see “The extent to which the competing processes of inland growth will continue to balance coastal shrinkage, until shrinkage under the predicted climate warming becomes dominant (Huybrechts and others,2004),will be seen as observations continue and model predictions are validated or improved.)
References against your suggestion:
Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations
Luthcke, S. B.; Zwally, H. J.; Abdalati, W.; Rowlands, D. D.; Ray, R. D.; Nerem, R. S.; Lemoine, F. G.; McCarthy, J. J.; Chinn, D. S. SCIENCE Volume: 314 Issue: 5803 Pages: 1286-1289 Published: NOV 24 2006
Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA – Deutsches Zentrum fur Luft- und Raumfahrt Gravity Recovery and Climate Experiment ( GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 +/- 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend ( – 113 +/- 17 gigaton/ year) from a near balance during the 1990s but is smaller than some other recent estimates.
Shepherd, Andrew; Wingham, Duncan. SCIENCE Volume: 315 Issue: 5818 Pages: 1529-1532 Published: MAR 16 2007
After a century of polar exploration, the past decade of satellite measurements has painted an altogether new picture of how Earth’s ice sheets are changing. As global temperatures have risen, so have rates of snowfall, ice melting, and glacier flow. Although the balance between these opposing processes has varied considerably on a regional scale, data show that Antarctica and Greenland are each losing mass overall. Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year. This is only a modest contribution to the present rate of sea-level rise of 3.0 millimeters per year. However, much of the loss from Antarctica and Greenland is the result of the flow of ice to the ocean from ice streams and glaciers, which has accelerated over the past decade. In both continents, there are suspected triggers for the accelerated ice discharge-surface and ocean warming, respectively- and, over the course of the 21st century, these processes could rapidly counteract the snowfall gains predicted by present coupled climate models.
Greenland ice sheet surface temperature, melt and mass loss: 2000-06
Hall DK, Williams RS, Luthcke SB, et al.
Source: JOURNAL OF GLACIOLOGY Volume: 54 Issue: 184 Pages: 81-93 Published: 2008
Increased runoff from melt from the Greenland Ice Sheet: A response to global warming
Author(s): Hanna E, Huybrechts P, Steffen K, et al.
Source: JOURNAL OF CLIMATE Volume: 21 Issue: 2 Pages: 331-341 Published: JAN 15 2008
Remote sensing of Greenland ice sheet using multispectral near-infrared and visible radiances
Author(s): Chylek P, McCabe M, Dubey MK, et al.
Source: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Volume: 112 Issue: D24 Article Number: D24S20 Published: DEC 14 2007
Estimation of steric sea level variations from combined GRACE and Jason-1 data
Author(s): Lombard A, Garcia D, Ramillien G, et al.
Source: EARTH AND PLANETARY SCIENCE LETTERS Volume: 254 Issue: 1-2, Pages: 194-202 Published: FEB 15 2007
Recent sea-level contributions of the Antarctic and Greenland ice sheets
Author(s): Shepherd A, Wingham D
Source: SCIENCE Volume: 315 Issue: 5818 Pages: 1529-1532 Published: MAR 16 2007
Importance of seasonal and annual layers in controlling backscatter to radar altimeters across the percolation zone of an ice sheet
Author(s): Scott JBT, Nienow P, Mair D, et al.
Source: GEOPHYSICAL RESEARCH LETTERS Volume: 33 Issue: 24 Article Number: L24502 Published: DEC 19 2006
Present-day sea-level change: A review
Author(s): Nerem RS, Leuliette E, Cazenave A
Source: COMPTES RENDUS GEOSCIENCE Volume: 338 Issue: 14-15 Pages: 1077-1083 Published: NOV-DEC 2006
Integrated regional changes in arctic climate feedbacks: Implications for the global climate system
Author(s): McGuire AD, Chapin FS, Walsh JE, et al.
Source: ANNUAL REVIEW OF ENVIRONMENT AND RESOURCES Volume: 31 Pages: 61-91 Published: 2006
Recent Greenland ice mass loss by drainage system from satellite gravity observations
Author(s): Luthcke SB, Zwally HJ, Abdalati W, et al.
Source: SCIENCE Volume: 314 Issue: 5803 Pages: 1286-1289 Published: NOV 24 2006
Hi John,
Thanks for your long post. Let’s cover Antarctica first.
First, here is another link to the Wingham et al. study I cited,which showed that the Antarctic ice sheet gained mass over the period 1992-2003 (since the other link appears to no longer function):
http://www.cpom.org/research/djw-ptrsa364.pdf
The authors analyzed 120 million European remote sensing (ERS) satellite altimeter echoes, taken on a 365-day 24/7 basis from October 1992 to February 2003, to encompass 11 years of continuous measurement. These show that the area measured gained mass (27±29Gt/yr) over this period.
There were two areas that could not be captured by satellite altimetry:
· An interior area encompassing 22% of the entire AIS, which was too close to the pole for measurement
· A small area along the coast encompassing 6% of the AIS, where contours were too steep to get an accurate satellite altimeter reading
The authors state, “Our estimate of the mass gain of the unsurveyed Antarctic interior is comparable to out estimate of the mass loss of the unsurveyed coast.”
In other words, the authors report a net mass gain of 27±29 Gt/year for the entire AIS over the 11-year period from October 1992 to February 2003.
This is the same period for which IPCC 2007 SPM states a loss of mass equivalent to an increase in sea level of 0.21±0.35 mm per year, or 71±88 Gt/year.
Since the IPCC claim is clearly contradicted by the Wingham et al. study, it follows that IPCC ignored (or “rejected”, or “refused to accept as correct”) published data (Wingham study) that contradicted its claim of net loss in the AIS equivalent to a sea level rise of 0.21 mm/year over the period 1993-2003.
(Please don’t rationalize that the “margin of errors of the two estimates show a piece of overlap, so are therefore not contradictory”.)
There are many reports out there, such as the many other studies, which you cited, that cover pieces of this time period or other time frames entirely, but none of these cover the entire period of the Wingham report or the IPCC claim, so are irrelevant to our discussion.
Regards,
Max
Max, Thanks. I really do not see a contradiction here, Wingham’s conclusion “In consequence,the data places a further burden on accounting (Munk 2003)for the twentieth century rise of 1.5 –2 mm/year”, seems to take 2 mm/year sea level rise as true. The papers I cited are not irrelevant. Andrew Shepherd’s paper (came after Wingham’s), for example, covers a decade also. They state “, data show that Antarctica and Greenland are each losing mass overall. Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year. This is only a modest contribution to the present rate of sea-level rise of 3.0 millimeters per year. However, much of the loss from Antarctica and Greenland is the result of the flow of ice to the ocean from ice streams and glaciers, which has accelerated over the past decade.”
Please elaborate on exactly where the contradiction is. Thanks.