I saw Al’s climate sci-fi movie, but I didn’t read the book. Via Tom Nelson, Robert Johnston has a refutation of some of Al’s claims in his book. This one caught my eye because it is a topic with which I am pretty familiar. Gore writes:
"People who want to deny global warming because it’s easier than dealing with it try to argue that what scientists are really observing is just the ‘urban heat island’ effect… This is simply wrong. Temperature measurements are generally taken in parks, which are actually cool areas within the urban heat islands… Most scientific research shows that ‘urban heat islands’ have a negligible effect…" (p. 318)
I can’t believe we let Al Gore lecture us on science. A few responses:
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I don’t think most skeptics deny that some warming has occurred in the 20th century. Satellite measurement, which is not subject to urban heat island biases, has shown several tenths of a degree C warming since the late 1970’s. However, skeptics do tend to argue that surface temperature networks do tend to overestimate the 20th century warming signal due in part to urban biases (not to mention over-zealous addition of fudge-factors by the alarmists running the data gathering). Of course, we also will dispute that "most" of this warming is due to anthropogenic CO2.
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The statement that most temperature measurements are taken in parks is so wrong as to be absurd. As Anthony Watts SurfaceStations.org climate station survey process has shown, the vast majority of stations are actually located near buildings (a predictable result of siting and cable length limitations of the most commonly used sensors). You don’t have to take my word for it, just scan the pictures yourself at random. I have had a lot of fun participating in this project. Here, by the way, is the Tucson station I surveyed. As you can see, the station is definitely located in a park[ing lot].
- We skeptics are often called "deniers" for not accepting that the theory of catastrophic man-made global warming is settled science. But if you want to see real denialism in the face of facts, one only has to look at the alarmist’s absurd position that, as Al Gore puts it, "urban heat islands have a negligible effect." The fact is that urban heat islands are well-known to science, and can cause the center of cities to be as high as 5-8C hotter than the outlying rural areas. It turns out that this is so horribly difficult to understand and prove that … my 14-year-old son did it for a science project. Here is the results of one of our data runs across town (details described in the article).
- Defenders of the surface temperature record will sometimes argue that they have successfully corrected for urban biases (leading to the cognitive dissonance of their saying that the biases have no effect and that they have fully corrected for them). But here is the problem: without detailed siting information, and surveys like that run by my son, it is impossible to make these corrections anything but guesses (ironically, many of the folks making this argument have opposed Anthony Watt’s survey process and continue to maintain that they can make better adjustments blind than having data of station siting). At most, the total warming signal we are trying to identify over the last century is about a degree F. But as you can see above, we found a 6 degree urban heat effect on the first night of our study, and we found a 9 degree urban effect our second night. You can see that not only does the magnitude of this heat island effect swamp the signal we are trying to measure, even the variability or uncertainty in assessing the urban bias is several times larger than the warming signal.
Update: Here is a new study debunking Gore’s claim that man-made global warming was melting the Kilimanjaro ice cap. This claim never made much sense, since even if temperatures were to warm by several degrees, they would still remain well below freezing all year long.
You keep on trotting out the same old bullshit, though you’ve been corrected time and time and time again.
1. You basically don’t understand what climate scientists are saying about urban heat islands. Yes, they exist. We all know that. You were cruel enough to tell your son he was discovering something new by detecting the Phoenix urban heat island, which is well known as a particularly large one. The point about them is that they are corrected for, so that they do not lead to an overestimate of the warming trend. If you exclude all urban measuring stations you derive exactly the same warming trend. A bit of simple, basic observation would clear this up for you as well: look up zonally-averaged temperature measurements and work out which parts of the world are warming fastest. If it is places full of cities, perhaps you could continue trying to blame urban heat islands. If, on the other hand, it is places far from cities, perhaps you’ll work out that urban heat islands cannot be causing us to significantly overestimate the amount of warming there has been.
2. You still keep insinuating that the surface record is inferior to the satellite record. Despite your feverish claims about evil data-riggers, urban heat islands and all that, the two methods give the same result. Do tell us how urban heat islands are contaminating the satellite record as well.
I think the most important point here is that Al Gore has set up a big fat strawman.
“People who want to deny global warming . . . try to argue that what scientists are really observing is just the ‘urban heat island’ effect”
That’s a complete misrepresentation of the skeptical position. Gore is playing on the ambiguity of the phrase “global warming.”
“The point about them is that they are corrected for, so that they do not lead to an overestimate of the warming trend. If you exclude all urban measuring stations you derive exactly the same warming trend.”
Only if you use corrected data.
The fact of the matter remains, when you look at raw, uncorrected US rural station data, there is no temperature trend in the US over the last century. I am all for the idea that there might be a need to correct this data – surely there are measurement biases. But perhaps I am just dumb and simple to assume that such measurement biases don’t vary smoothly with time, somehow increasing in effect as we approach the present day. I’d expect any biases to be mostly systematic and/or random, adding either a constant correction factor or canceling out – neither case influencing the overall trend. But perhaps I am wrong, and the rural station keepers have been smoothly altering their habits, methodologies, and equipment over the last century in such way that they have been understating temperatures more and more in the modern era.
“A bit of simple, basic observation would clear this up for you as well: look up zonally-averaged temperature measurements and work out which parts of the world are warming fastest. If it is places full of cities, perhaps you could continue trying to blame urban heat islands. If, on the other hand, it is places far from cities, perhaps you’ll work out that urban heat islands cannot be causing us to significantly overestimate the amount of warming there has been.”
The northern hemisphere contains about 90% of the world’s population, and thus most of the worlds large/dense cities, and is warming significantly faster than the southern hemisphere.
1. Remarkably the fact that the USA covers only 2% of the Earth’s surface still seems to elude some people.
2. And within the northern hemisphere, which bits are warming fastest? Is it China, or India, both urbanising rapidly? Is it Siberia, or the Arctic? Is there any correlation between urbanisation and recent temperature trend? Let us know what you find.
So Al Gore can’t tell the difference between a Park and a Parking Lot.
He would have made a swell President.
the loss of most of the most rural stations in areas like the arctic and siberia has had the effect of driving up apparent temperatures as the stations that remain are, in fact, much more likely to be in urban/developed areas. a great deal more extrapolation is used to fill in grid squares than formerly. if you look at the big jumps in temperatures in these areas and compare them to the decrease in number of stations, the correlation very strong.
the loss of most of the most rural stations in areas like the arctic and siberia has had the effect of driving up apparent temperatures as the stations that remain are, in fact, much more likely to be in urban/developed areas. a great deal more extrapolation is used to fill in grid squares than formerly. if you look at the big jumps in temperatures in these areas and compare them to the decrease in number of stations, the correlation very strong.
There are enough moving parts in temperature measurements that anyone with a particular preset position can cherry pick enough tidbits to justify his position.
1. All agree that UHI exists.
2. Nevertheless, IPCC “spokespeople” have stated a number of times that the UHI effect is negligible. IPCC’s FAR referenced Parker’s wind study to support the conclusion that the UHI effect is negligible. (An even-handed analysis likely would say that Parker’s study is controversial.)
3. Temperature trends estimated by GISS are adjusted in innovative ways to account for UHI effects. At the same time, GISS adjusts for other factors that might have a trend impact (such as TOB). Therefore, GISS ends up adjusting upward the trend in urban temperatures 42% of the time. Many observers view this as bizarre. For example, while observed temperatures in New York City have been quite flat, GISS inserts in persistent increase in the temperature trend.
4. The steepest trend upwards has often been in Arctic and Siberian sites, and observers would not put them into the UHI effect.
5. However, the Arctic and Siberian sites are far from pristine. As the number of Siberian sites plummeted, the reported temperatures skyrocketed. (Also, it is possible that decades ago, Siberian temperatures were reported lower by local officials to get more fuel supplies.) North American Arctic sites have heat generation sources extremely close to the thermometer – it doesn’t take a UHI to get a false trend!
6. Nevertheless, satellite measurements also point out that the Arctic and Siberia has had temperature increases.
7. On the other hand, satellite measures have been around only since 1979, and much of the controversy are GISS adjustments in prior decades.
8. GISS, HadCrut and satellite measurements are in remarkable agreement. There are some differences that one can explore, but they are not in violent disagreement.
9. However, this agreement is for less than three decades. Looking at the record for 28 years does not reveal an impending disaster for global temperatures. Rather it reflects what one would expect for the PDO and other oscillations over this time period. Temperatures in mid 2008 were not noticeably higher than they were in 1980.
Nicely put, DB. But ScienList will be around to refute it all with his gigantic brain soon. Stand by to be bitchslapped by his enormous intellect.
Me, I’m just a neanderthal. I still cannot understand how you can accurately predict a catastrophe with a statistically insignificant amount of data. Oh, wait, you cannot.
Love it: Keep going. Let’s squash this scam.
…and another thing about the comment someone made about temperature measurements and urban heat islands.
Someone said: “The point about them is that they are corrected for, so that they do not lead to an overestimate of the warming trend”.
What are you nutty? I would like to see exactly how this is corrected for and what algorithms they use for each station! I have been doing military environmental testing in controlled labs for many years. So I at least have some fractional gray matter for this:
Does the “correction” include cloud cover on any particular day, wind, humidity, pressure levels? How about absorbtion rates of the paints and meterials near the sensing stations. How about calibration? I doubt if these little weather stations are as sophisticated as the VERY expensive, calibrated environmental chambers I have employed which STILL yield some skewed results based upon how the sensors are orented and placed. Give me a break. If there is correction going on, give us an example of it.
1. incredibly the fact that the USHCN provides 1221 stations to the GHCN 7280 still escapes one boneheaded alarmist.
2. when you extend (1.) back in time the percentage and importance of the USHCN increases as a ratio of the steadily retreating temperature recorded in that bygone era.
For anyone interested:
Here’s McKitrick and Michaels 2007 testing correlation between urbanisation and temperature trends.
http://www.agu.org/pubs/crossref/2007/2007JD008465.shtml
Here’s de Laat and Maurellis doing the same.
http://www.knmi.nl/~laatdej/2006joc1292.pdf
John Daly does a wider literature survey.
http://www.john-daly.com/graytemp/surftemp.htm
Al does have a big strawman in there.
Climate scientists do not claim that the UHI effect has no impact on the thermometers, they claim that it has no effect on global warming.
For Al to deny that thermometers within cities don’t have inflated readings is just ignorant.
Then sadly, they apply correction factors much larger than the actual drift over time. It amazes me that anyone can claim that any of this is settled science.
There is so much slop in the data and corrections still…
Hey the picture is at the University of Arizona near the Math East building and behind, obviously, the Physics and Atmospheric Sciences Building…..I am a recent Alum. Graduated in May 08 with a degree in chemical engineering and some professors were not exactly excited that I was going to work for ExxonMobil. To comment on the “Scientist'” post…..bottom line is that anybody who had done research, or worked with people who have, know what “Good Science” is, and Global Warming is not good science. The data is created or ignored to prove a point, and when asked for is not divulged to the people who need it. Mathematically speaking, there models are flawed and fudged. Its a debocle for the scientific community.
morganovich – if you derive a temperature trend only from the stations which have a continuous record, excluding any which have stopped functioning, how does it compare to the temperature trend from all stations?
Mike Strong – if you want to know how the corrections are done, simply read the papers describing them.
papertiger – apparently you think that there is some relation between the fraction of all global weather stations within a geographical region, and the size of that geographical region. No matter how many of the world’s weather records come from the US, it still only covers 2% of the world’s surface.
Stevo – you misrepresent De Laat and Maurellis. They are not talking about urban heat islands at all: did you read their final sentence? Finally, we point out that it seems unreasonable to assume that the ‘classical’ urban heat island (different heating due to different land cover) is the cause of the enhanced surface warming over industrialized regions since the area coverage of urbanized regions is far too small to explain the spatial extent of the regional temperature trend enhancements discussed in this paper.
Scientist,
One question: why not just use satellite data? Are there issues with their temperature measurements? It sounds like you said the satellite trend matches the corrected station database trend anyways, doesn’t that mean we should now roll with the satellites (for future data and for data back to when satellites started collecting this data) and avoid these corrections and controversy? Why do we still need the surface stations?
Quoting Scientist –“apparently you think that there is some relation between the fraction of all global weather stations within a geographical region, and the size of that geographical region. No matter how many of the world’s weather records come from the US, it still only covers 2% of the world’s surface.”
The United States may only occupy 2% of the Earth’s surface, but we supply 17% of the temperature data. Does the GHCN devalue the US data so that it only represents that 2% value, or does it leave it alone, effectively giving it added weight since there is more of it? As an analogy, if I was in a group of fifty people, would my voice be counted as one because I was only one person, or would it be counted as more because I was 8.5 times louder than anyone else?
For that matter, oceans cover approximately 71% of the Earth’s surface. Statistically, that means the temperature readings over the oceans should heavily outweigh any numbers generated over land surface. Does anyone have access to the algorithms being used to determine global temperatures so we can be sure that the numbers being given take proportionality into consideration?
hmmm – yes, the satellite trend matches the surface trend. Why would you want to drop one set of measurements entirely, though? Why wouldn’t you want to have two independent measures, each of which is a check on the other?
Keith – your analogy is completely meaningless. If you want to know what the global average temperature is, you do not weight areas by the number of weather stations within them. Can you see why that would be ridiculous?
Does anyone have access to the algorithms being used to determine global temperatures, you plaintively ask. Even a tiny bit of research would surely have led you to the GISTEMP website, where their codes are freely available. Your question strongly suggests that you haven’t done any research.
scientist-
how would you propose to get the records from stations that have stopped functioning? if you are asking do the individual continuous records of stations still in the network show the large and sudden jumps in temperature shown by the reported network as a whole over the period when many stations were removed, no they do not.
my point is that in the 3-4 years in which there was a dramatic removal of stations (mostly rural)from the terrestrial network, average temperature increased markedly owing to no change in the earth, but to a change in measurement methodology.
Just in case anybody is misled about the integrity of GISS data: I have read supporting documentation, and I have spent much time at the GISTEMP website. My conclusion can be summarized in four words. “Neither reproducible nor verifiable.” The code for GISS adjustments was released last year under protest and with the note that it would soon be revised. Many highly intelligent people have been stumped trying to follow the procedures and getting the code to run. Some insights have been gained about the code, and if GISS were to be examined by itself, I would have little confidence on what it is doing to today’s temperatures. HadCrut is even more of a mystery, and if these two land-surface temperature records were all that AGW relied on, then I would say AGW has no valid temperature data to support its hypothesis. However, the GISS and HadCRut get a large degree of validity because of their similarity to satellite records. (Also, although I have not seen a definite and comprehensive analysis of the growing season length, I sense the increased time between killing frosts also confirm estimates of temperature trends in the last three decades of the 20th century.) To be sure satellite records have their own issues, but those issues are independent of GISS issues and there is no reason to suspect that they are biased in the same direction. Nevertheless, look at the temperature trends over the last 28 to 29 years — the entire record of where satellite data can be compared to GISS & HadCrut. Do you see a monotonic, threatening trend in temperatures?
Scientologist,
“They are not talking about urban heat islands at all:”
Did I say they were? Who’s misrepresenting here?
And what is the significance of the word ‘classical’?
Incorrect. Deriving global temperatures only from stations with a continuous record does not eliminate the warming trend. Measured average global temperatures have increased markedly because actual average global temperatures have increased markedly.
Stevo – you claimed they were ‘doing the same’ as McKitrick and Michaels. They are not. Surely you have read their paper fully, and so you don’t need me to explain what they mean by ‘classical’.
I didn’t say they were doing the same as McKitrick and Michaels.
And I don’t need to read the paper since the explanation of what they mean is given in the quote. What I asked about was the significance.
Scientist, I went and checked GISTEMP, and they do explain how they divide up the Earth for their statistical averaging on this page. But one thing snagged at my mind a bit. Step three of the process involves dividing the planet into 8000 grid boxes. This would create boxes of roughly 63,759 square kilometers within which an average temperature anomaly is computed and then supplied to the global computation. It is how the average temperature is computed that bothers me.
That average temperature anomaly is computed from the temperature stations within that grid box, and also any within 1200 kilometers. To give a graphic perspective so people can visualize this, let’s say my grid box is centered in St. Louis, Missouri. My local grid average is determined by not only the stations within my grid (roughly within 375 kilometers of me), but also from stations in Pittsburgh, Atlanta, Dallas, and Minneapolis, to name just a few. Basically, the radius of effect means that my one grid box is not determined from the 63,759 square kilometers within it, but from the 4.52 million square kilometers around it, an area 71 times as large.
Based upon this computation design, the United States should be represented by roughly two grid boxes if you are looking at total area involved in determining the average temperature anomaly compared to total area of the US (9,826,630 square kilometers total area of the United States divided by the 4,521,600 square kilometers derived from the 1200 kilometer radius of effect). But the US grid sample is still based upon the 63,759 square kilometer grid box determination, so the total US grid boxes are 154. That would seem to me to heavily weight the US sample.
Why the 1200 kilometer area of effect? Doesn’t this mean that certain stations get counted multiple times? Based upon my math above, it would suggest many stations in the United States get counted over 77 times. Does the temperature in St. Louis really effect the temperature in Atlanta, and vice versa? Surely, we could just use the temperatures provided by the stations within the grid boxes to determine that grid box’s average anomaly and work out a good global average from that.
Stevo – yes, you said they were doing the same as McKitrick and Michaels.
Keith – stations are weighed by distance from the point for which the anomaly is being computed. I do not know what you are trying to say about the US temperature measurements. Are you saying they should be given greater weight, or that they are given greater weight but shouldn’t be? They are not given greater weight in measuring global average temperatures, and nor should they be.
Does the temperature in St. Louis really effect the temperature in Atlanta, and vice versa – why don’t you do some investigating yourself? I always find it astonishing how often I see people here asking questions like this which they can investigate themselves in a matter of minutes. Get the GISS data for St. Louis, and for Atlanta, and compare them.
After looking at all of our chatter. It now appears that all the points and counterpoints mimic the explanations by analysts as to why the stock market goes up or down day to day. The important fact is that the Antarctic ice extent is now larger than ever recorded since they launched the satellite to look at the poles in 1979. It looks like it to me… unless the data is wrong and my reading glasses are smudged. This past winter, and today, the northern Arctic ice content seems larger than last year at this same time. If you look at the University of Illinois Polar Study Group at Cryosphere Today…you can see the thaw/freeze trends showing global ice content now trending upward. And nobody can detect that water levels in the ocean have risen in the past 100 years based upon markings of water level by some famous navigator who visited some Pacific Island long ago.
So instead of arguing over ground-based weather station and urban heat islands… I just want to know why here in San Diego my gas bill last winter showed I used more “therms” than I have ever used in the past 20 years, it snowed in Baghdad for the first ever known, China had the worst snow storms, the snow pack melt and water content to feed Lake Meade is still running up 34% from the the “all-years” average and the upper Midwest had some of the longest, coldest temperatures ever recorded. I also went snow skiing in the local mountains in June…that hasn’t happened in 20 years.
So, like the stock market…I want to get a few more years of data, especially in light of the much lower than average solar radiance the past couple years… Anybody want to bet me $100 that solar activity versus CO2 is the real culprit in the past few years of temperature changes?
And by the way… I always post my real name…rather than trying to be anonymous behind a screen name. My credentials as a 30 year engineer are mine and I stand by them. I wouldn’t mind engaging any of you if you reveal your credentials and emails.
Mike
Keith: the methodology does seem highly suspect. One wonders why they have abandoned the large body of literature on countouring/interpolation/Kriging in favor of their own quirky methodology.
They are attempting to average the value of a scalar field (temperature), which is continuous over the entire surface of the earth, based on discrete measurements of that field. It seems to me that the best approach would be to use one of the many available algorithms that interpolate a continuous field based on discrete measurements, and then use the interpolated field to calculate the average value of the field. This would quit naturally and automatically correct for sparse and concentrated data points, by weighting them appropriately in the interpolation step.
joshv,
The GISS’ data are self contradictory. Their own 1200km and 250km “smoothing radius” (a href=”http://data.giss.nasa.gov/gistemp/maps/”>use this page) produce different temperature trends for a SAME period.
So their results are precisely evidence that their temperature is at best inconsistent, at worse useless to assess the 20th century’s small warming trends.
So, let me get this straight. The earth is really, really old. I mean, really, really, really old. And humans have been gathering scientific data (inexact, ever-evolving data) for a very short time to determine that it is a fact that global warming is man-made? This sounds like more elitist liberal bullshit. How embarassing.