Three papers published in the Science last week purport to debunk an important argument advanced by skeptics of the notion of catastrophic, manmade global warming. The skeptics’ argument is that while temperatures measured on the Earth’s surface seem to indicate that global temperatures have increased at a rate of about 0.20 degrees Centigrade per decade (the original estimate was 0.35, may I not that is a 50% error, there's a big difference from a fight on a test and a one hundred) since the 1970s, temperatures measured in the atmosphere by satellite and weather balloons have shown only a relatively insignificant amount of warming for the same time period (about 0.09 deg. C/decade).
The implication of the skeptics’ argument is that whatever warming seems to be happening on the Earth’s surface, similar warming isn’t happening in the trophosphere. This unsimilarity is caused by the urban heat island effect.
It is well known that changes in land use will cause changes in average ground temperature. Cities are hotter than the surroundign countryside - the urban heat island effect. Croplands are warmer than forested lands, and so on. A high percentage of weather stations that were out in the countryside forty years ago are now surrounded by concrete and skyscrapers and asphalt and so on. Which makes them register warmer. These facts are very well known within the field, of course. There is no controversy.
http://eetd.lbl.gov/HeatIsland/HighTemps/UrbanProfile.gif
What is controversial about these heat islands is whether, and if so how much, this additional warmth affects trends in [global] temperature record. The current state of the science is that the effect on the global temperature trend is small to negligible—see below. So researchers take the raw temperature data from stations near cities and reduce them by some amount to compensate for the urban heat island effect. This reduction is calculated in different ways, depending on who does it. Most algorithms are based on population size. Population is proportional to the amount subtracted.
Sounds good but it isn't. R. Bohm studied Vienna in 1998. Vienna has had no increase in population since 1950, but it has more than doubled its energy use, and increased living and commercial space substantially. The urban heat island effect is much stronger, but calculated reduction is unchanged, because it only looks at population change.
It used to be assumed that urban heating was unimportant because the effect was only a fraction of total warming. The planet warmed about .3 degrees C in the last thirty years. Citites are typically assumed to have heated around .1 degrees C. The Chinese report that Shanghai has warmed 1 degrees C in the last twenty years. That's more than the entire global warming of the planet in the last hundred years. "Between 1987 and 1999, the mean nighttime surface temperature heat island of Houston increased 0.82 ± 0.10 degrees C." says D. R. Steutker, in Remote Sensing of Environment. Manchester, England, is now 8 degrees warmer than the surrounding countryside.*
The average temperature of Pasadena, Calafornia, went from 62 degrees F in 1930, to 65.5 F in 2000. LA has about 14,531,000 people. The average temperature of Berkeley, CA, with only 6,250,000 people, from 1930 to 2000 has increased .5 degrees F. Death Valley, CA, with no urbanization, from 1932-2000 has increased .15 degrees F. In smalltown McGill, NV, from 1930 to 2000, it went from average 48 to 47. Guthrie, OK went from 60.5 to 59.9. Boulder, where NCAR (National Center for Atmospheric Research, where a lot of global warming research is done), has gone down half a degree. Turman, MO went down two and a quarter! Charleston, South Carolina went up over half a degree, and New York City went up 1 degree. Cities in New York with less urbanization such as Syracuse, Albany, Oswego and Westpoint, went down 1.5, 1.2, 1, and .35 degrees. And if you go back allllll the wayyyy from 1826, to 2000, then you will find the line actually rises steadily... about 0 degrees F. Its a horizontal line. New York went up 5.2 degrees F, and Albany went down half a degree in 180 years.
We know CO2, the gas everyone is worrying about, has increased the same amount everywhere in the world. And its effect is presumably pretty much the same everywhere in the world. That's where the term "global" warming comes from. But New York and Albany are only one hundred and forty miles apart, you can drive from New York to Albany in three hours. Their carbon dioxide levels are identical. But somehow New York's temperature went up 5 degrees, a temperature increase that would kill many species, while across the street it got colder a little bit. In the last 180 years, New York has grown to seismic proportions, about 8 million people, whereas Albany has grown to quite less.
The urban heat island effect makes cities hotter than the surrounding countryside; and this is a local effect, completely unrelated to global warming. In this case, we used all raw temperature data, and it is tainted by the very scientists who claim global warming is a worldwide crisis. It is adjusted downward, but the question is: Is it adjusted down enough? It is never a good policy for the fox to guard the henhouse. Such procedures are never allowed in medicine, where double-blind experimental designs are required.
One of the new Science studies reported that the satellites had drifted in orbit, causing errors in temperature measurement. Corrections to the satellite data, according to the researchers, would increase the atmospheric warming estimate to 0.19 deg. C/decade -- more in line with the 0.20 deg. C/decade warming of the Earth’s surface. Another study reported that heating from tropical sunlight had skewed the balloon temperature measurements.
Ben Santer of the Lawrenhce Livermore National Laboratory, one of the studies’ authors, told USA Today that, “Once corrected, the satellite and balloon temperatures align with other surface and upper atmosphere measures, as well as climate change models.”
So is it really game-set-match in favor of the global warming alarmists?
University of Alabama-Huntsville researcher Roy Spencer, a prominent climatologist, factored the newly reported corrections into his calculations, his estimate of atmospheric warming was only 0.12 deg. C/decade - higher than the prior estimate of 0.09 deg. C/decade, but well below the Science study estimate of 0.19 deg C/decade and the surface temperature estimate of 0.20 deg. C/decade.
As to the claimed errors in the weather balloon measurements, Spencer says that no other effort to adjust the balloon data has produced warming estimates as high as those reported in the new study and that it will take time for the research community to form opinions about whether the new adjustments advocated are justified.
Climate expert Dr. Fred Singer of the Science and Environmental Policy Project says the temperature adjustments are “not a big deal.”
“Greenhouse theory says (and the models calculate) that the atmospheric trend should be 30 percent greater than the surface trend - and it isn’t,” says Singer. “Furthermore, the models predict that polar [temperature] trends should greatly exceed the tropical values - and they clearly don’t... In fact, the Antarctic has been cooling,” adds Singer.
