Nature has a way of slapping our
hands when we meddle. Already two
unforeseen products of reducing air
pollution (the Clean Air Act?) are
■ Reduced biomass—There’s less light
dispersion so plant understories are
receiving less light (energy) and processing less CO2;
■ Faster global warming—More light
(energy) is directly penetrating the
atmosphere and striking the earth’s surface, turning into heat.
Hindsight says both of these effects
should have been foreseen; they are
fairly obvious. Politically correct journalism suggested less volcanic activity
as the cause of clean air, but I’m sure
active actuaries will want to check the
facts—I’m 87 and retired.
An applicable axiom of mathematics is that you can’t solve a problem
until it’s properly stated. Ask why, in all
that’s been written about global warming, life’s dependence on CO2 is never
mentioned. Wake up and smell the roses! They also need CO2!
John H. Beales Jr.
Anthropogenic and natural forcings
temperature Change, Centigrade
1900 1920 1940 1960 1980 2000
aDaPteD from “ComBinations of natUral anD antHroPogeniC forCings in t WentietH-CentUry Climate,”
JOURNAL OF CLIMATE
17, no. 19 (2004): 3723. rePrinteD WitH Permission.
charting climate change
In Susan Woerner’s article (“Managing the Risk of Climate Change”) in the
July/August issue of Contingencies, I was
puzzled by the chart on Page 50 showing rising temperatures through the 20th
century and two other lines showing
“forcings.” How are the forcings related
to the temperature observations and the
temperature scale on the vertical axis?
The author states the chart reinforces
the human factor in climate change and
that the temperature “observations cannot be explained without considering the
The choice of years shown in the
chart was also puzzling. Does the chart
extend to 2005 temperatures and forcings (the red and black lines) or just to
2000 (the blue line)? Since the article underlying the chart was published in 2004
and first submitted in 2003, how could
the chart show 2005 temperatures?
I obtained the underlying Journal of
Climate article, from which the reader
can learn the following:
■ The article is a study of climate models, the assumptions (forcings) that are
input into the models, and simulation
runs of those models.
■ The study considers only five factors
that can influence temperature. There
are only two “natural” factors considered: solar and volcano. How solar is
factored into the models isn’t described
in the article. One may surmise that the
article’s authors have concluded that
other natural factors, such as clouds,
have no impact on temperatures.
■ There are three anthropogenic factors (forcings) considered in the study.
One of the factors is a large category of
items labeled greenhouse gases, which,
according to an accompanying table,
include carbon dioxide, several other
gases, and water vapor. Presumably,
the authors are using measures of all
these gases and not just the proportions
caused by human activity. No mention is
made of the human-caused, or anthropogenic portion, although the Journal
article and the graph in Contingencies
both refer to all of the greenhouse gas
effects as anthropogenic. Is water vapor
now a human-caused greenhouse gas?
The other anthropogenic forcings considered are sulfate aerosols and ozone.
■ The five factors are assumed and
then simulated in the climate models.
Their effects are isolated within the
models, and the authors derive variance
statistics to see which of the forcings are
most correlated with observed temperatures. Some possibilities seem not to
have been considered: ( 1) There are other important factors and combinations
of factors, ( 2) the forcings assumed may
be incorrect and may change over time,
( 3) the assumed human-caused portion
of greenhouse gases may be incorrect,
( 4) measurement error, and ( 5) correlation isn’t causation.
The observed temperatures used in
the study appear to have been from the
1890-to-2000 period. From my reading
of the Journal article, I believe the lines
in the graph in the Contingencies article
should stop at the year 2000.
I’m curious to know what the graphs
would look like if the study were extended to August 2009. Could there be a new