[ExI] The Climate Science Isn't Settled [was: Re: climategateagain]

[Emlyn]

2009/12/2 spike <spike66 at att.net>:
>> How to Talk to a Climate Sceptic
>> Coby Beck
>>
>> http://scienceblogs.com/illconsidered/2008/07/how_to_talk_to_a
>> _sceptic.php
>>
>> "Below is a listing of all the articles to be found in the
>> "How to Talk to a Climate Sceptic" guide...
>> Emlyn
>
> Weather stations everywhere that were set up a long time ago would naturally
> show an increase in temperature because of urbanization.  Cities are warmer
> than rural areas, because there are heat sources everywhere.  Practically
> every long-operational station would see that effect, so the science
> community must figure out a way to compensate for that.  If we had just the
> raw data and no compensation model, we would vastly overestimate the warming
> of the planet.  So if the CRU guys were either intentionally or mistakenly
> exaggerating the warming, it could be from undercompensating for
> urbanization.
>

>From the link I posted:

http://scienceblogs.com/illconsidered/2006/02/warming-due-to-urban-heat-island.php

Objection:

The apparent rise of global average temperatures is actually an
illusion due to the urbanization of land around weather stations, the
Urban Heat Island effect.

Answer:

Urban Heat Island Effect has been examined quite thoroughly and simply
found to have a negligible effect on temperature trends. Real Climate
has a detailed discussion of this here. What's more, NASA GISS takes
explicit steps in their analysis to remove any such spurious signal by
normalizing urban station data trends to the surrounding rural
stations.  It is a real phenomenon, but it is one climate scientists
are well  aware of and have taken any required steps to remove its
influence from the raw data.

But heavy duty data analysis and statistical processing aside, a
little common sense and a couple of pertinent images should put this
idea to bed.  Here is an image, taken from Astronomy Picture of the
Day (a wonderful site, by the way), of the surface of the earth.  It
is a composite of hundreds of satellite images all taken at night.
(The large version is well worth the download time!)

http://www.cobybeck.com/illconsidered/images/earthlights02_dmsp.jpg

Aside from being very beautiful, it is a perfect indicator of
urbanization on earth. As you can see, the greatest urbanization is
over the continental United States, Europe, India, Japan, Eastern
China and generally coastal South America.

This next image was taken from NASA GISS. It is a global surface
temperature anomaly map which shows warming (and infrequently,
cooling) by region.

http://www.cobybeck.com/illconsidered/images/global-anomalies.gif

Look at North America, look at Europe, at Asia, Australia, Africa and
the Poles and compare them to the urbanization in the image from APOD.
There is quite simply no way to discern any correlation whatsoever
between urbanization and warming.  If the UHI effect were the cause of
warming in the globally averaged record, we would see it in this map.

The claim that Global Warming is an artefact of Urban Heat Island
Effect is simply an artefact of the Urban Myth Effect.

Addendum: Wikipedia has a very good article on this subject. Among all
the interesting details it mentions a few papers that directly discuss
efforts to identify and quantify UHI influences on the global
temperature trend including this one which would be a good one to
cite:

    A 2003 paper ("Assessment of urban versus rural in situ surface
temperatures in the contiguous United States: No difference found"; J
climate; Peterson; 2003) indicates that the effects of the urban heat
island may have been overstated, finding that "Contrary to generally
accepted wisdom, no statistically significant impact of urbanization
could be found in annual temperatures." This was done by using
satellite-based night-light detection of urban areas, and more
thorough homogenisation of the time series (with corrections, for
example, for the tendency of surrounding rural stations to be slightly
higher, and thus cooler, than urban areas). As the paper says, if its
conclusion is accepted, then it is necessary to "unravel the mystery
of how a global temperature time series created partly from urban in
situ stations could show no contamination from urban warming." The
main conclusion is that micro- and local-scale impacts dominate the
meso-scale impact of the urban heat island: many sections of towns may
be warmer than rural sites, but meteorological observations are likely
to be made in park "cool islands."

-- 
Emlyn

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