Green Myth-Busting: Global Average Temperature
Myth: Global temperature data is inaccurate and/or too sparse to be able to establish a meaningful average temperature over the entire planet. Therefore, any claims of global warming are unfounded.
Fact: NASA has collected and acquired massive amounts of temperature data from various sources, including land-based, meteorological stations, sea surface temperature measurements from ships, and measurements taken from satellites. This data encompasses the entire planet, and is run through a method that is explained on NASA’s website, which results in a statistically significant global average temperature.
The first thing to note here is that there are not many who still make this argument, at least not among climate scientists. The IPCC, in its latest report, actually states that global warming is "unequivocal". Even skeptical scientists, such as Richard Lindzen and John Christy, will admit that we are indeed warming. Their only argument is against the cause of the warming, which is where most skeptics’ arguments have shifted. This should be a clue that there is no argument against warming, however some continue to insist that the planet is not warming.
It seems that the major impetus for the recent resurgence of this argument is a website, www.surfacestations.org, which attempts to question data collection equipment. This is actually a very nifty little trick. This site, launched in June of this year, has established a fairly large following. These devoted followers are commissioned to go out and take pictures of the US meteorological stations. Armed with these pictures, surfacestations.org scrutinizes them, looking for indications that they might be susceptible to a warm bias. This has filled many contrarians’ minds with the idea that the entire temperature data set is flawed, which is ultimately the point. Not surprisingly, there is no mention on the site of existing methods for removing biases from temperature measurements. First, the thermometers are now protected by Stevenson screens (emphasis added):
A Stevenson screen or Instrument shelter is a meterological screen to shield instruments against precipitation and direct heat radiation from outside sources, while still allowing air to circulate freely around them. It forms part of a standard weather station. The screen creates, as near possible, a uniform environment in relation to the air outside. - Wikipedia
Second, NASA’s GISTEMP compares urban stations to rural stations, in an attempt to further remove any potential biases:
We modify the GHCN/USHCN/SCAR data in two stages to get to the station data on which all our tables, graphs, and maps are based: in stage 1 we try to combine at each location the time records of the various sources; in stage 2 we adjust the non-rural stations in such a way that their longterm trend of annual means is as close as possible to that of the mean of the neighboring rural stations. Non-rural stations that cannot be adjusted are dropped. - NASA GISS
Another common argument is that we simply don’t have enough temperature data to be able to compute a global average temperature. This argument usually comes with a map of the world, showing the locations of existing surface meteorological stations. Obviously, on such a map, there are very large areas that are not covered (oceans, deserts, mountain ranges, etc.). However, NASA states that they have sufficient data, dating as far back as 1880:
The NASA GISS Surface Temperature Analysis (GISTEMP) provides a measure of the changing global surface temperature with monthly resolution for the period since 1880, when a reasonably global distribution of meteorological stations was established…We limit our analysis to the period since 1880 because of the poor spatial coverage of stations prior to that time and the reduced possibility of checking records against those of nearby neighbors. - NASA GISS
A major problem for both of these arguments is that they only focus on land-based temperature readings. This is because there is a preponderance of evidence in favor of global warming outside of those temperature measurements, which are completely ignored by these objections. In order to truly call global warming into question, one would also have to prove satellite data, borehole analysis, glacial melt, sea ice melt, sea level rise, proxy data, and rising ocean temperature to be flawed.
UPDATE: A new instance of this questioning of temperature data occurred when NASA made some small corrections to data at the turn of the millenium, thanks to a tip from Stephen McIntyre from Climate Audit. This was a good tip, and NASA’s data is now more accurate for it, but some skeptics have tried to misrepresent it as proof that NASA’s temperature data is faulty. Recently, Fox News provided an excellent example of this misrepresentation:
On Special Report, Jim Angle reported that NASA was forced "to admit it was wrong when it said that 1998 was the hottest year on record" and that NASA "now says 1934 was the hottest year, followed by 1998, then 1921." But Angle did not inform viewers that NASA’s revision affected annual temperature rankings for the United States only; it had no effect on the annual global temperature rankings. - Media Matters
As the fine folks at Media Matters pointed out, while the change did result in 1934 topping 1998 as the hottest year in the US, it had literally no effect on global temperature trends, and actually even a very miniscule effect on US trends. Looking at the global temperature graph below, one can see that the global warming trend is still very much intact:
Tags: Climate Change, global warming, Green Myth-Busting, NASA, Science and Tech
- Uncategorized
August 15th, 2007 at 9:52 pm
Hmm, looks like NASA was wrong, and has admitted it. Read on.
A Toronto blogger’s number-crunching skills turned up an error in the math NASA used to determine historic temperatures, forcing the agency to own up to an embarrassing mistake.
NASA had said 1998 was the hottest year on record in the U.S. but later revised the statistics, issuing a new list that instead named 1934 as the hottest year on the books.
Toronto-based blogger Steve McIntyre found the error. In a tongue-in-cheek posting on his blog climateaudit.org, he compared the race for the top spot to the leaderboard results from the U.S. Open.
“There has been some turmoil yesterday on the leaderboard of the U.S. (Temperature) Open and there is a new leader,” he wrote on Aug. 8.
“Four of the top 10 are now from the 1930s: 1934, 1931, 1938 and 1939, while only 3 of the top 10 are from the last 10 years (1998, 2006, 1999). Several years (2000, 2002, 2003, 2004) fell well down the leaderboard, behind even 1900.
McIntyre scrutinized NASA’s numbers, looking closely at data that recorded how warm a place is at a specific time, compared to its 30-year average.
He found that the numbers for 1999 to 2000 seemed abnormally high, and discovered that after 1999, the data wasn’t being adjusted to figure in the times of day the readings were taken or the locations where they were taken.
He forwarded his findings to NASA, and the review was ordered. Eventually, NASA released a new list of the hottest years on record.
In addition to naming a new year as the hottest, NASA also reduced the mean U.S. temperature anomalies by .15 C for the years 2000 to 2006.
Some consider the adjustment a blow to Al Gore and others who maintain the planet is heating up as the result of global warming. But NASA has downplayed the corrections and even McIntyre has suggested the new numbers would have little impact on climate policy.
McIntyre has said he had fun discovering the flaws, but called the adjustment a “micro-change.”
August 16th, 2007 at 2:01 pm
Robert,
I appreciate the extra info, but I’ve already addressed that in my post. This correction is by no means a "blow to Al Gore and others who maintain the planet is heating up as [a] result of global warming". That is a severe overstatement, based on a lack of understanding of climate science. As you can see from the updated graph at the end of my post, the global warming trend is still very much intact. In fact, this small change in US temperatures had literally no effect on a global scale, and even a very small effect on US temperature trends.
August 16th, 2007 at 2:01 pm
Robert,
I appreciate the extra info, but I’ve already addressed that in my post. This correction is by no means a “blow to Al Gore and others who maintain the planet is heating up as [a] result of global warming”. That is a severe overstatement, based on a lack of understanding of climate science. As you can see from the updated graph at the end of my post, the global warming trend is still very much intact. In fact, this small change in US temperatures had literally no effect on a global scale, and even a very small effect on US temperature trends.
August 16th, 2007 at 3:14 pm
We recently did a temperature survey of our compressed gas (welding bottles) storage areas at the job site. Some of the bottles had surface temperatures 20 to 30 deg F higher than ambient while others were very close to ambient. It appeared in some cases that the placement of surrounding structures or the attitude of protective enclosures was inhibiting the cooling effect of airflow. In a couple of cases, we had no explanation as to why certain locations yielded higher temperatures than similar storage areas elsewhere on the site. Our only resolution was to relocate them to minimize the possibility of overheating. However, it does suggest that some areas my have an unintended “warm bias”. With or without a Stevenson Screen protecting the instruments, there may be some natural variations from one area to another. It is also worth noting that the survey was performed in an area of just a few hundred acres.
You should probably mention when the “now” is in the phrase “thermometers are now protected by Stevenson screens”. Since the inventor died in 1887, it is not exactly a new technology. However, the phrase makes it appear as though its use at weather stations only recently became standard practice, which would give us skeptics something to question.
Regarding NASA’s recent temperature mistake, it is not the only error the agency has made. A few nearly forgotten unmanned mission failures and some devastating manned mission catastrophes reveal that even rocket scientists make mistakes.
As to the graph, what is the temperature that coincides with the “.0 C” anomaly? How do we know that our assumed baseline median temperature is correct? If 1934 was the hottest year on record, where is the annual mean spike for that year? The black line should have had a spike for 1934. Was the baseline reset to flatten the curve? What many people don’t know is that statistics can be manipulated in a number of ways. The most preferred method of manipulation is to throw out the data on the extreme ends of the scale. Take the following test scores:
30 75 80 95 100 85 90
The average is 79.3. However, a statistician would likely throw out the grades that do not fit the trend (i.e. drop 30, 95 & 100). The new average is 82.5. The variance in the two averages is only 3.2, but it’s the difference between a “C” and a “B” on the transcript. People need to understand that statistics can be used to make sense of a mountain of data. However, it can also be used to manipulate that mountain of data into a preconceived solution.
As always, I enjoyed the post.
August 20th, 2007 at 1:35 pm
Let me state it clearly: global average temperature has no more statistical meaning that average weight of all fruits in an supermarket (counted between watermelons, apples, oranges and strawberries). If tomorrow the average weight goes up, is it because all fruits became heavier or because there are no more strawberries ?
What’s worse, this global yearly average is an average of averages (monthly, weekly, daily), which enhances the craziness of the concept.
I spent some time on the Internet, searching for the global average temperature - you can hear naming it constantly, but nobody tells you how much is it - well, it’s ~15°C.
So I should worry if tomorrow it’ll be 1 or 2 degrees higher ? So 15°C is OK, but 17°C can bring down armaggeddon ? Are you kidding or is it serious ?
By the way: Stevenson screen is no more than a box in which you put all instruments - it can not protect those instruments from an unnatural heat of the surrounding environment - if you put it in the middle of a parking place or nearby the A/C unit it _WILL_ register higher temperatures, regardless of any screen you would try to apply. Of course the measurement is false both way, if you try to exclude the effect of heated environment - you have no actual result, if you take the actual result, you have high temperature of incorrect environment. It’s the place, not instruments to be changed.
August 20th, 2007 at 9:36 pm
Re: Christopher,
*Sigh* Yet another basement brainiac who has outsmarted the PhD’s … Don’t these professors know ANYTHING about their very own profession? If it weren’t for all these helpful laypeople, science would go all to hell! [Yes, it IS sarcasm ...]
On a more sober note, is it that people don’t realize that there are subjects they are not expert on? Or is it because people think there are no such thing as “knowledge”? Or do they believe that years and decades studying a subject DOESN’T improve knowledge? How is it that regular Joes and Janes (rarely Janes, though, which by itself should say something) think they can sit in their armchair and casually pick apart frontline science? Where does this come from?
Yes, it’s late, I’m tired, and I’ve just watched Adam Curtis “The Century of the Self”. But still …
August 21st, 2007 at 1:14 pm
Please forgive this rebuttal, but the basement brainiacs and armchair climatologists are no different than you. All of us non-professor types are listening to and reading about what the professor’s are saying, and since there is still dissension in their ranks, there will naturally be dissenension in ours. Apocalyptical global warming science has become based upon consensus via forced computer models rather than observable and repeatable experimentation. The effects of the perceived problem are merely theories, not facts.
August 21st, 2007 at 1:30 pm
Re: themotie
Oh, please, Reverend, forgive my sin. How can I question The Real Truth put upon us by High Priests of Climate Change Witnesses.
Who am I to ask what “average global temperature” is ? Please, to become a True Believer I need only one Holy Answer:
the global average temperature was measured at noon, or at midnight ???
[No, it IS NOT sarcasm ... - I would really like to know]
August 22nd, 2007 at 12:30 pm
If steadily increasing carbon dioxide concentration is the driver for increasing temperature, why does the temperature drop for some years? Why was it hotter in 1998 than it has been in the subsequent nine years?
August 27th, 2007 at 11:23 am
This issue has become so politicized and polarized that it’s hard to know who or what to believe. Scientists are not above “hyping” and “spinning” their positions to make them seem more certain than they really are. They do this in order to make themselves heard in the increasingly cacophonous debate. After all, if they’re not noticed, how will they renew their funding grants?