UPDATE: 8/18 10:30AM I spoke with Dr. Judith Curry by telephone today, and she graciously offered the link to the full paper here, and has added this graphic to help clarify the discussion. I have reformatted it to fit this presentation format (side by side rather than top-bottom) While this is a controversial issue, I ask you please treat Dr. Curry with respect in discussions since she is bending over backwards to be accommodating. – Anthony
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[Update] My thanks to Dr. Curry for showing the graphic above, as well as for her comment below and her general honesty and willingness to engage on these and other issues. She should be a role model for AGW supporters. I agree totally with Anthony’s call for respect and politeness in our dealings with her (as well as with all other honest scientists who are brave enough to debate their ideas in the blogosphere). I also commend the other author of the study, Jiping Liu, for his comments below.
However, as my Figure 2 below clearly shows, any analysis of the HadISST data going back to 1950 is meaningless for the higher Southern latitudes. The HadISST data before about 1980 is nonexistent or badly corrupted for all latitude bands from 40°S to 70°S. As a result, although the HAdISST graphic above looks authoritative, it is just a pretty picture. There are five decades in the study (1950-1999). The first three of the decades contain badly corrupted or nonexistent data. You can’t make claims about overall trends and present authoritative looking graphics when the first three-fifths of your data is missing or useless. – willis
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Guest Post by Willis Eschenbach
Anthony has posted here on a new paper co-authored by Judith Curry of Georgia Tech, entitled “Accelerated warming of the Southern Ocean and its impacts on the hydrological cycle and sea ice”. The Georgia Tech press release is here. Having obtained the paper courtesy of my undersea conduit (h/t to WS once again), I can now comment on the study. My first comment is, “show us the data”. Instead of data, here’s what they start with:
Kinda looks like temperature data, doesn’t it? But it is not. It is the first Empirical Orthogonal Function of the temperature data … the original caption from the paper says:
Figure 1. Spatial patterns of the first EOF mode of the area-weighted annual mean SST south of 40 °S. Observations: (A) HadISST and (B) ERSST for the period 1950–1999. Simulations of CCSM3 (Left) and GFDL-CM2.1 (Right): (C, D) 50-year PIcntrl experiment (natural forcing only),
Given the title of “Accelerated warming”, one would be forgiven for assuming that (A) represents an actual measurement of a warming Southern Ocean. I mean, most of (A) is in colors of pink, orange, or red. What’s not to like?
When I look at something like this, I first look at the data itself. Not the first EOF. The data. The paper says they are using the Hadley Centre Sea Ice and Sea Surface Temperature (HadISST) data. Here’s what that data looks like, by 5° latitude band:
Figure 2. HadISST temperature record for the Southern Ocean, by 5° latitude band. Data Source.
My first conclusion after looking at that data is that it is mostly useless prior to about 1978. Before that, the data simply doesn’t exist in much of the Southern Ocean, it has just been shown as a single representative value.
So if I had been a referee on the paper my first question would be, why do the authors think that any analysis based on that HadISST data from 1950 to 1999 has any meaning at all?
Next, where is the advertised “Accelerated warming of the Southern Ocean”? If we look at the period from 1978 onwards (the only time period with reasonable data over the entire Southern Ocean), there is a slight cooling trend nearest Antarctica, and no trend in the rest of the Southern Ocean. In other words, no warming, accelerated or otherwise.
Finally, I haven’t even touched on the other part of the equation, the precipitation. If you think temperature data is lacking over the Southern Ocean, precipitation data is much worse. The various satellite products (TRMM, SSM/i, GPCC) give widely varying numbers for precipitation in that region, with no significant correlation between any pair (maximum pairwise r^2 is 0.06).
My conclusion? There is nowhere near enough Southern Ocean data on either side of the temperature/precipitation equation to draw any conclusions. In particular, we can say nothing about the period pre-1978, and various precipitation datasets are very contradictory after 1978. Garbage in, you know what comes out …
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Tamara said:
“Therefore, AGW must continue to be the determinant factor for future Antarctic climate, despite the fact that the period of the study includes natural climate cycles that could have resulted in similar warming/cooling oscillations. This cooling blip is a temporary feature in an overall upward trend?”
That is what Co-author Liu said in Discovery News:
That additional precipitation has yet another effect that helps increase sea ice: It lowers the salinity of the surface water, which slows the melting of sea ice, Liu explained. The result is that the growth of sea ice has outpaced melting.
“But the ice building and preserving effects are only temporary, Liu told Discovery News, who with Curry published their findings in the latest issue of the Proceedings of the National Academy of Sciences.”
http://news.discovery.com/earth/antarctic-sea-ice-growth.html
In regards to Liu’s comments in Discovery News:
“But the ice building and preserving effects are only temporary, Liu told Discovery News, who with Curry published their findings in the latest issue of the Proceedings of the National Academy of Sciences.”
Does that mean, that if their hypothesis is proven correct, it is only temporary?
Is this a new hypothesis, that the ice building in Antarctica is only temporary?
I see nothing in the data that they have presented to give credibility to this statement. This sounds like Lui is analyzing the data within the context of a pre-determined belief system. I say belief because their data does not support this statement.
Dave, works for me.
Obviously it also works for almost every climate scientist out there too.
Climate scientists seem to be a breed of their own.
Even when a normal person would see good news, they see doom and bad news.
The Arctic might recover – no it won’t.
The Antarctic ice is growing – no it isn’t.
Temps are not increasing as much – yes they are
Crops grow better – no they don’t
and on and on………..
Knowing that climate is not stable and does not stay on that “normal” line. Knowing that temps should be a lot lower and how lucky we are, only climate scientists could turn this into a bad thing.
I visualize them all living in some deep dark hole. With only their peers. So they can pat themselves on the back, reaffirm each others doom and gloom, live each day to create more dooms day scenarios, and never see the light of day.
How depressing it must be to work in that field………..
check this out, the UK Met Office is pondering the challenge of surface temperature data sets for the 21st century http://www.surfacetemperatures.org/home
REPLY: Thanks Judith, I’ve been aware of this for a few days (a journalist tipped me off, showing just how bad the Met Office PR is) and I’m working on a post about it. – Anthony
One more note on Liu’s comment that the ice building and preserving is only temporary. I agree that it is given a long enough time scale. Everything on Earth is temporary, especially climate. It is strange that we approach things with the assumption that everything was right with Earth at time X. For a lot of scientist in the climate field, that time frequently seems to be right before satelite measurements started, and that explains a lot.
Judith is just another [snip] warmist… only she likes to masquerade around pretending to be impartial.
glacierman says:
“Does that mean, that if their hypothesis is proven correct, it is only temporary?
Is this a new hypothesis, that the ice building in Antarctica is only temporary?
I see nothing in the data that they have presented to give credibility to this statement.”
I agree. And what if it is only temporary? The only way to rule out natural variability is through models that fail to adequately model natural variability, let alone anthropogenic warming. All we can do is wait and see if the models are correct.
That is why I am hoping Dr. Curry or Dr. Liu will tell us the purpose of this hypothesis. All I can see is an artificial mechanism for explaining that, even though it looks like the Antarctic is behaving as it should, it is really doing something paradoxical that can be explained by greenhouse gas emissions.
Judith Curry & Jiping Liu,
I thank both of you and Anthony for the opportunity to discuss your paper.
Thank you to the ever curious Willis, modern Renaissance man. You set these posts up with skill. : )
Judith and Jiping, I have a question, but first let me set it up by some comments.
I find the structural elements of your paper to be:
a) take some climate data from a mainstream source (picked out of other sets of mainstream data sources)
b) take some climate models from the typical genre available (picked out of other typical genre models)
c) run the models with the data
d) the models predict warming
e) hypothesize a physical mechanism(s) to show how this predication of warming can occur
f) conclude that future warming is consistent with: 1) the data, 2) models and 3) your hypothesized mechanism(s)
QUESTION for Judith & Jiping: Can you discuss how the structure of your paper relates to scientific reasoning per se? I see the key to your paper seems to be centered solely on the models. The models were designed for showing, what is considered by mainstream climate science to be an established certainty, that CO2 conc increases must cause future warming. The need for a hypothesized physical mechanism is the result of the models showing what they were designed to show. It appears that the models were not inclusive of the physical mechanism, so how could they yield results consistent with your hypothesized physical mechanism? Shouldn’t your study have shown the models deficient in regards your mechanism?
John
richard telford says:
August 18, 2010 at 7:30 am
Since no demonstration I make against the creed would ever be accepted by the true believers here, I instead offer a simple way that Eschenbach could try to falsify the claims made in the paper instead of relying on incredulity. He appears to prefer his incredulity, perhaps his readers do to, than risk finding out that his test of reasonableness is little more useful that extispicy. The other reason for not attempting the analysis myself is that Eschenbach finds so many thinks incredulous that there is not time in the day to test them all.
I will however point out that the average of several measurements is much more precise that that of the original measurements.
_____________________________________________________________
That is a fallacy or a bait and switch. If you have a uniform material and do repeated measurements then yes you get a more precise answer by averaging.. That is not what is happening here. The measurements are separated by space and time and therefore are not repeats of the same measurement. By averaging individual measurements of separate nonhomogeneous “samples” you loses information not gain it.
Example: If I have four industrial lines making widgets by three different companies in four different plants and I take a measurement at each plant does averaging the test results give me a more precise answer? Or does it give me garbage?
John Whitman, you ask an interesting question. Here is how this arose. Both Jiping Liu have conducted sea ice research for a long time (in my case several decades). Both of us have a strong perspective of thermodynamics of sea ice. In recent years we have been investigating the modes of natural variability and their impact on the arctic and antarctic climates. We have a new grant from NSF on developing better satellite data products of sea surface temperature and evaporative fluxes from the Southern Ocean.
Jiping Liu wanted to understand why the extent of the Antarctic sea ice has been increasing. With the context provided above, he developed a hypothesis related to the hydrological cycle, and wanted to understand the relative impacts of natural variability vs AGW. We already know that the data sets would be inadequate by themselves, since we needed a number of decades worth of data. The climate model simulations for the 20th century provide an internally consistent data set of the variables needed to understand these processes, and further the 20th century simulations are run with natural variability only and then natural forcing plus anthropogenic forcing. So we used the observations we did have to assess which models to use. The model data was analyzed, which helped support and refine our original hypothesis. Then we looked at the 21st century model simulations, to interpret the processes in the perturbed climate. This describes the general history of our reasoning and how the idea for this emerged.
James says:
August 19, 2010 at 8:22 am
“Judith is just another [snip] warmist… only she likes to masquerade around pretending to be impartial.”
I don’t think she has ever denied being a warmist, though I suspect she may be more a luke-warmer than anything else. So I think your charge of masquerading as impartial is invalid. In my view, what she is doing is trying to open lines of communication. Yes, part of her agenda may be trying to persuade sceptics of the validity of AGW, but I can forgive her that because were the shoe on the other foot, I’d be trying to persuade AGWers of the merits of scepticism.
We are all entitled to our views and to try to promote them, but the key is how we do that. Dr. Curry does in fact sometimes accept the criticisms of sceptics. Maybe not to the extent that her views are overturned, but nonetheless, to show an uncharacteristic degree of openness and respect. I personally value that approach as being much better than the antagonistic and hostile responses sceptics usually get from AGW supporters. Some actual communication takes place: maybe not as much as we’d like, but any at all is welcome.
“”” Judith Curry says:
August 19, 2010 at 3:50 am
Steven Wilde, I am not exactly sure what your question is. But the hydrological cycle relates surface evaporation, precipitation, and the storage of water in the atmosphere both as humidity (water vapor) and also cloud water (liquid and ice). Whereas some people talk about the acceleration of hydrological cycle globally, it makes more sense to me to talk about it regionally. As an example, look at the Sahel. It has undergone periods of drought and then relative abundance of rainfall. This reflects a different strength of the local hydrological cycle. In terms of the global hydrological cycle, as the atmosphere and ocean surfaces warm, the ocean can evaporate more water and atmosphere has the capacity to “hold” more water, even as the atmospheric relative humidity remains the same. The basic physics behind this is the Clausius-Clapeyron equation, based on the first and second laws of thermodynamics, that explains the saturation vapor pressure. “””
Dr Curry, I still don’t have a good understanding of what you (or Steven Wilde either) mean when you say: “acceleration of the hydrological cycle.”
Now I know what “acceleration” is; a change in velocity; or shall we say a “speeding up” in general.
So what evidence (data) does either of you have that the hydrological cycle is “speeding up” ? If it took 72 hours from the time an H2O molecule leaves the ocean surface for the atmosphere, till it becomes part of a cloud, and subsequently is precipitated out as rain/snow/sleet/hail/whatever; back in 1980, how long does that cycle take in today’s climate ? And how do we know that anyway ?
Now I DO understand a quite different concept; of the amount of evaporation/condensation/cloud formation/precipitation/whatever, increasing (or decreasing) in that 30 year time frame.
For example Frank Wentz (RSS Santa Rosa) et al in SCIENCE for July-7-2007 published “How much more Rain will Global Warming bring ?”
In that paper they showed from actual real satellite based data measurements, that a one deg C increase in the mean global surface (or lower troposphere) Temperature results in a 7% increase in total global evaporation; a 7% increase in total atmospheric water content; and a 7% increase in total global precipitation. Now of course total evap and precip must be the same over time, or we would end up with the oceans overhead.
They also reported that the GCMs agreed with them on the total atmospheric water content; but placed the evap/precip increase at only 1% to 3% (there’s that mandatory 3:1 climate science fudge factor).
So there’s a case where the GCMs were in error by as much as a factor of seven from actual observed measurements.
So I understand how the amount of water involved in the “hydrological cycle” might increase (or decrease) but I don’t for the life of me see that it accelerates.
Now the (really) important thing that Wentz et al did NOT report in their paper; but which I have mentioned (here at WUWT) is the effect on clouds.
Now I don’t know about Y’alls down there in Georgia, Dr Curry; but out here in California, we like to have CLOUDS with our precipitation; that is real clouds. Not whispy noctilucent things in the stratosphere, but real dark precipitating moisture containing clouds. Like as a totally wild guess, I would suggest about a 7% increase in the total global precipitable cloud cover for that same one deg C rise in mean global surface Temperature.
Now such clouds have big white tops that reflect a lot of solar energy back into space, then they absorb and scatter a lot more solar energy, and they can get very dark underneath; as I know they certainly do in the mid west; and that reduces the amount of solar energy that reaches the surface in the shadow zone of those clouds.
Now if that one deg C Temperature rise were to persist for some climatically significant time period like about 30 years or so, I would expect that the 7% (say +/-50% for a 3:1 range) increase in total global precipitable cloud cover, to also persist for 30 years.
Well to be honest Dr Curry; I wouldn’t expect any such thing; because that cloud increase; which must accompany any increase in precipitation, is an astronomically huge negative feedback cooling process; and it simply wouldn’t allow that one deg C rise in mean global surface temperature to persist for 30 years; or even 30 months or weeks.
So you see Dr Curry; no matter what CO2 or any other trace GHG tried to do to change the global mean temperature (either up or down) that very large change in total global cloud cover would simply squash such a puny effort. Even TSI changes which don’t seem to result in detectable cyclic temperature changes on earth, get regulated out of the system by CLOUD MODULATION.
It’s NOT the CO2; IT’S THE WATER !!
May I suggest that you give each of your students a copy of Frank Wentz, et al’s SCIENCE paper for July-7-2007.
George
Why is the hydrological cycle not functioning the same way in the Arctic?
“Jiping Liu wanted to understand why the extent of the Antarctic sea ice has been increasing. ”
A much simpler hypothesis is that the sea ice is increasing because the sea is getting colder 🙂
Occam’s razor, anyone?
Judith Curry said:
“As an example, look at the Sahel. It has undergone periods of drought and then relative abundance of rainfall. This reflects a different strength of the local hydrological cycle.”
With respect, Dr. Curry that is an example of a global change having a regional effect. The subtropical high moves latitudinally to and fro across the Sahel on multidecadal time scales and that affects rainfall amounts. That movement of the subtropical high is not somehow disconnected from everthing else. All the air circulation systems move poleward or equatorward in unison over longer time scales and that is the sole source of ALL regional climate variability.
Until you consider the global effects of changes in the speed of the hydrological cycle then of course you will not understand my question.
I have looked again at my question and it appears to be clear enough. It is not necessary for water surfaces to warm when evaporation increases from more downward IR. Convection will increase nonetheless simply because water vapour is lighter than air. Increased evaporation = increased convection = faster hydrological cycle with no need for any observed surface warming because the extra energy has gone to latent heat and is whisked away upward.
Or did you mean something quite different by your use of the concept of an accelerated hydrological cycle ?
“”” Gail Combs says:
August 19, 2010 at 9:09 am
richard telford says:
August 18, 2010 at 7:30 am
Since no demonstration I make against the creed would ever be accepted by the true believers here, I instead offer a simple way that Eschenbach could try to falsify the claims made in the paper instead of relying on incredulity. He appears to prefer his incredulity, perhaps his readers do to, than risk finding out that his test of reasonableness is little more useful that extispicy. The other reason for not attempting the analysis myself is that Eschenbach finds so many thinks incredulous that there is not time in the day to test them all.
I will however point out that the average of several measurements is much more precise that that of the original measurements.
_____________________________________________________________
That is a fallacy or a bait and switch. If you have a uniform material and do repeated measurements then yes you get a more precise answer by averaging.. That is not what is happening here. The measurements are separated by space and time and therefore are not repeats of the same measurement. By averaging individual measurements of separate nonhomogeneous “samples” you loses information not gain it. “””
You go Gal ! Gail too ! You’re my Hero(ine) !
Mathematically; one can take any quite arbitrary set of numbers; add them all up, and divide by the number of numbers in the set, to arrive at an average. And it is just as good an average as any other average one might compute. Except in this case, it has exactly no significance whatsoever; and as you point out, simply throws away virtually all of the information that was contained in the original set (namely the value of each of those numbers).
You could do the same process with all of the telephone numbers in your local telephone directory; to arrive at an average telephone number in your area; and the result is of no consequence; well unless it turned out to be your telephone number. Well it might not even be any real telephone number.
That’s about what GISSTemp is too, and HADCruT. So why don’t they complete the process, and simply print one number for the average of all of the data they have ever had.
On average, nothing ever happens; and if you eliminate the Temperature differences between real places and replace them with some average or some trend, then you just erased whatever heat engine is moving energy around the planet.
From the paper:
“Over the course of the second half of the 20th century, strong warming in the middle
latitudes of the Southern Ocean with weak cooling in the high latitudes is hypothesized here to lead to an enhanced hydrological cycle in the Southern Ocean”
So cooling in the high latitudes existed BEFORE the hydrological cycle was enhanced. Was this cooling also caused by greenhouse warming? Would the hydroglogic cycle still be enhanced without this cooling trend, enough to lead to the increase in sea ice?
“”” Dave Springer says:
August 19, 2010 at 7:11 am
George E. Smith says:
August 18, 2010 at 7:14 pm
Unfortunately it is never legal under any circumstance no matter what, to use any “Far Side” panel in a lecture, or slide presentation or on the web; so I can’t post it here. Gary Larson simply does not allow ANY usage of his works; but you can legally buy any one of his products and get a legal print of any panel for your own personal gratification.
That might be what Larson desires but that’s not what the law has to say about it.
http://en.wikipedia.org/wiki/Fair_use “””
Well if your read that wiki thing; it essentially says you can do whatever you like and nobody will stop you.
Now I believe it is true that if you “purchase” or otherwise legally obtain (gift) some already commercialized Copyrighted material, that “Fair use” allows you make say an archival copy for your own use; but that doesn’t give you licence to give a copy to someone else.
If you actually purchase, as I did, a suitable for framing copy of a Far Side panel, you will get a letter in which it states:-
This cartoon is for personal purposes only and may not be used in a commercial setting, nor may it be reproduced (including, but not limited to, photocopying or digital scanning.)
And it is signed by one Anica Wong whose only job is policing the far Side copyright infringements, for the owners.
The computer software companies went even further to protect their works by simply NOT selling them; so you only have purchased a licence to use the software; but you have no ownership rights of the software.
“”” TomVonk says:
August 19, 2010 at 2:20 am
The reason for this is simple offshore flow. Since the water around Antarctica is usually warmer than the near water land surface, air over the water rises then descends over the land causing wind to blow off shore.
Very correct comment . The data I accumulated during my stay in Antarctic (only summer) completely supports that .
a) The prevailing winds come from the continent
b) the air temperatures at/near shore are always colder (actually subzero) when the winds come from the continent
c) It cannot rain when temperatures are sub zero but it snows instead what is the case most of the time both in winter and in summer .
d) The Antarctic Peninsula , especially its northernmost tip is a very special atypical case . Its temperatures in summer are anomalously high with regard to 99,99% of Antarctic and have always been . “””
“”” d) The Antarctic Peninsula , especially its northernmost tip is a very special atypical case . Its temperatures in summer are anomalously high with regard to 99,99% of Antarctic and have always been . “””
So what am I missing here? If the Northermost tip of the Antarctic peninsual has always been high with regard to 99.99 % of Antarctica; then clearly is is NOT anomalous at all; but is the normal state of affairs.
And in this case it is absolutely perfectly normal in that the northern tip of the Antarctic peninsula is alone in having such a low latiduinal co-ordinate. No other place in Antarctica is as far north as the Northernmost tip of the Antarctic peninsula; and ergo one would expect it to be warmer than the rest of Antarctica; specially with the whole Atlantic and Pacific parts of the Southern ocean sloshing back and forth there twice a day.
George E. Smith says:
On average, nothing ever happens; and if you eliminate the Temperature differences between real places and replace them with some average or some trend, then you just erased whatever heat engine is moving energy around the planet.
_________________
Yabbut if you don’t have any data for real places can’t you just use made up data from GCM’s and get the result you want? It might seem silly to the rest of us, but (apparently)… that’s climate science!
Tamara, the cooling at the high latitudes is observed, this is attributed to a strong Antarctic Oscilliation associated with a strong circumpolar current that isolates the high latitudes from exchange of heat with lower latitudes. The AAO is a component of natural variability.
Steven Wilde, the term accelerated hydrologic cycle is generally associated with an increase in precipitation. The scale of this can be referred to as global, or regional.
Judith,
First I will congratulate you on your valor. You are indeed brave to face this crowd, and whatever the outcome of this debate, you are a stronger person than those who hide in academia and post only on heavily moderated (censored) sites.
Next, I will try my best to be civil but I find most of your comments to be disingenuous at best.
Your comments on this thread seem to portray a paper which merely postulates that a warming antarctic could result in increasing sea ice, reversing as the heat increases further in the 21st century;
“166. Judith Curry says:
August 18, 2010 at 1:31 pm
David, we chose 1999 as the end date because that is the end date of the 20th century climate model simulations. Again, the main point of this paper was not so much to document the temperature trend, but rather interpret the behavior of the sea ice in the context of surface temperatures, precipitation, and evaporation.”
Uh, I’ve read the paper, and if that was your intent, you should throw this paper away and start over.
Let’s begin with the very first lines of your paper;
pg. 2
“The observed sea surface temperature (SST) in the Southern Ocean shows a
3 substantial warming trend for the second half of the 20th century. Associated with the
4 warming, there has been an enhanced atmospheric hydrological cycle in the Southern
5 Ocean that results in an increase of the Antarctic sea ice for the past three decades through
6 the reduced upward ocean heat transport and increased snowfall. The simulated SST
7 variability from two global coupled climate models for the second half of the 20th century
8 is dominated by natural internal variability associated with the Antarctic Oscillation,
9 suggesting that the models’ internal variability is too strong, leading to a response to
10 anthropogenic forcing that is too weak. With increased loading of greenhouse gases in the
11 atmosphere through the 21st century, the models show an accelerated warming in the
12 Southern Ocean, and indicate that anthropogenic forcing exceeds natural internal
13 variability”
Those lines don’t indicate anything about this just being a conjecture of what would happen IF the ocean warmed in the southern hemisphere. They state rather unambigously that the southern ocean has gotten warmer, and further indicating that this warming could only have been caused by anthropogenic forcings, which will only get stronger in the next century.
Let’s look at your first point; substantial warming in the Antarctic Ocean during the second half of the 20th century. From the graphs on page 15 of your paper I see only one of five that indicates ANY significant warming at all, one shows mild warming, one shows mild cooling, and two are somewhat ambiguous. Further, given the weakness of the oldest data there is no way that your statement about a warming southern ocean should go unchallenged. While we’re looking at those graphs, by the way, lets take a moment to reflect on the ridiculous nature of the last two; your projections for the 21st century. WHAT in the first five graphs (actual data) suggests to you anything like what you are projecting in the last two?
Then there’s this gem;
pg. 3
“Comparisons of temperature
12 profiles collected during the 1990s with profiles collected starting in the 1930s that were
13 obtained from both ship-based hydrographic surveys and autonomous floats show that the upper
14 1000 m of the Southern Hemisphere Ocean has warmed substantially (~0.2ºC) during this time
15 period, and that the warming is concentrated within the ACC (4). Modeling studies also indicate
16 that the Southern Ocean might be undergoing rapid climate change.”
“might be undergoing rapid climate change” Does that line really have any place in a scientific paper? So much for a neutral perspective.
This paper clearly exhibits a warmist agenda and you clearly use data prior to 1950 at least in making the statement regarding ‘warmed substantially’. Further, I find nothing in the paper at all to indicate this is just a first wobbly attempt. In fact this paper seems to state very authoritatively that the ocean has gotten warmer, and that this warming has probably resulted in increased snowfall and sea ice, and further was very likely caused by anthropogenic forcings.
Looking at the graphs at the top of this page (which are based on your stated data source) shows that there’s very little actual warming in the data from 1950 through 2000; cooling at 65-70 S & 60-65S, slight warming at 55-60S, none to possibly cooler at 50-55S, definitely slightly cooler at 45-50S, and somewhat warmer at 40-45S, though this has completely disappeared in the last decade, hardly “substantial warming trend”.
Yet you indicate;
pg. 4
“Thus, the observed SST pattern in the
21 Southern Ocean during the second half of the 20th century is dominated by a broad-scale
22 warming that accounts for one third of the total variance (28% for HadISST and 29% for
23 ERSST). The strongest warming is found in the middle latitudes of the Southern Ocean, and the
24 warming is reduced poleward. Because HadISST and ERSST use different data sources, analysis
25 procedures, and historical bias corrections, the good agreement between them supports
26 confidence in the analyzed Southern Ocean warming during the second half of the 20th century.”
and this;
pg. 9
“With increased loading of greenhouse gases through the 21st century, the models suggest
7 that there is an accelerated warming in the Southern Ocean. Moreover, there is a strong poleward
8 expansion of the warming from low to high emissions (Fig. 1d-f). As shown in Fig. 4b, SST
9 under sea ice in the 2090s is a few tenths degree warmer than that in the 2000s, and the warming
10 could be as large as ~1-1.5°C in the ACC. Thus, the pronounced warming in the Southern Ocean
11 during the 21st century offsets and exceeds the cooling effect associated with the decrease of
12 upward ocean heat transport as a result of the enhanced hydrological cycle”
All of this puts you very firmly in the AGW camp, and actually detracts from the paper itself, the crux of which I would tend to support; it is possible for a warmer ocean to produce more snow and sea ice, and that the effect would probably reach a tipping point where this effect reverses itself, resulting in a rapid decline in sea ice and converting some substantial portion of what had been falling as snow into rain. There doesn’t seem to be much real evidence in this regard, as we don’t have a warmer ocean to test it on. I don’t mean to be rude but the term GIGO came around a long time before you and seems to apply here. I will not stoop to calling your work by that term, and you do clearly seem to understand that (at best) you’ve got a starting point here. I further understand why your paper would downplay uncertainty and play up the AGW aspect. But I hope you can understand my disdain for that particular aspect. If you need to pander to get published you ought to consider whether you are dealing with an honest broker. You cannot get ‘a little bit pregnant’. You seem to be a skillful scientist, but once you start down that path you will eventually find yourself having to answer for poor behavior at best and academic dishonesty at worst. I believe there are yet more shoes to drop on that front.
You’ve clearly spent a lot of time effort and effort on this (or at least your grad students have), and I do hope that your willingness to address critics and share your data and methodology catches on with the climate science establishment at large. Aside from the agenda driven statements and overstating of the case for a warmer southern ocean and greenhouse gases as the driving factor I think this paper was pretty clear in establishing the process by which increased SST could lead to more snowfall and possibly more sea ice in the antarctic. But it’s not proven yet and the data you’ve used don’t seem (to me) to support the notion that we’ve had ANY warming in the southern ocean.
Oh, and EOF = Principal Component Analysis. Most people will understand what that means.
Cheers.
Judith Curry says:
August 19, 2010 at 11:55 am
Tamara, the cooling at the high latitudes is observed, this is attributed to a strong Antarctic Oscilliation associated with a strong circumpolar current that isolates the high latitudes from exchange of heat with lower latitudes. The AAO is a component of natural variability.
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But if it was warming we would attribute it to…..?
Judith Curry says:
August 19, 2010 at 11:56 am
Steven Wilde, the term accelerated hydrologic cycle is generally associated with an increase in precipitation. The scale of this can be referred to as global, or regional.
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I can understand the need for circumspection when facing the frothing furies, but circumlocution does not appease, it annoys.
“Accelerated hydrologic cycle” is synonymous with “increase in precipitation” would have been unambiguous, but since that’s not what was said, I’m obliged to seek the significance of the words “generally associated”, all the while suspecting that their semantic values should be ignored and a more oblique semiotic identity should be ascribed.
Eventually, I’ll get around to pondering why “acceleration” and “increase” are interchangeable.