Global warming myths (was: Kyoto, Driving our car)

Hal Finney (hal@rain.org)
Tue, 9 Dec 1997 08:55:13 -0800

mark@unicorn.com writes:
> There are two ways to measure the Earth's temperature; you can either
> take a lot of surface measurements, try to correct for errors, then feed
> them into a computer model which may or may not reflect reality, or you
> can just launch satellites and measure it. The CAG (Computer Aided Guess)
> systems do, indeed, say that the temperature has increased and is
> increasing.
>
> But what happens when you stop guessing and actually measure it?
>
> >From http://wwwssl.msfc.nasa.gov/newhome/headlines/essd12mar97_1.htm:
> >Dr. Roy W. Spencer (NASA Marshall Space Flight Center) and Dr. John
> >Christy (The University of Alabama in Huntsville) have used the Microwave
> >Sounding Units (MSUs) flying aboard NOAA's TIROS-N weather satellites to
> >construct a continuous record of lower tropospheric (from the surface to
> >about 4 miles) temperatures since the first MSU was launched in late 1978.
> >The lower tropospheric temperature trend has been calculated to be -0.04
> >degrees C/decade.
>
> So there you have it; the temperature of the atmosphere is decreasing by
> 0.04 degrees per decade. This isn't a guess, it's an actual measurement,
> and matches measurements taken in situ by balloon. As a programmer and
> physicist measurements give me a warm fuzzy feeling that computer-aided
> guesses just can't match.

I don't think global warming is as well understood as ozone destruction.
The measurements appear much more ambiguous and the evidence for human
impact is less clear. But in the interest of fairness here is what the
EPA has to say about these atmospheric measurements, from:

http://www.epa.gov/globalwarming/climate/trends/temperature.html

> Although scientists have incontrovertible evidence that the surfaces
> of the land and oceans have been warming, some scientists are not
> yet convinced that the atmosphere is also warming. but as the figure
> shows, the 1979-95 data series may be too short to show the trend.
>
> Part of the reason that satellites do not show a warming trend may be a
> coincidence regarding the year that NASA began to collect this data. 1980
> was much warmer than the temperature that prevailed during the previous
> few decades. Thus, even the surface temperature measurements--which show a
> steady warming trend over the last century--do not show much of a warming
> trend when one only considers data since 1979. Balloon data, which shows
> the same absence of warming over the 1979-95 period shows a significant
> warming trend from 1958 to 1993. Measurement errors associated with the
> new technology, and cyclical variations in temperature due to El Ninos,
> may also be responsible for the lack of a warming trend. Nevertheless,
> to many scientists, the absence of a warming trend in the satellite data
> provides an important caution that there is still much to learn about
> the global climate.

[Note - the figure referenced in the first EPA paragraph is not present;
HTML source comments indicate that they plan to incorporate a figure
from the international IPCC study.]

We know that two decades is not really enough to expect to see a clear
trend, and apparently it happened that the beginning of the interval was
unusually warm, swamping the trend. Expanding the time frame as shown
by the balloon measurements does appear to confirm the warming trend.
The satellite measurement results should be considered with this
information in mind.

Hal