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Let's Get Serious?   Let's Get Real!
Volume 3, Number 27: 18 October 2000

"The world needs to get serious about managing the exponential growth of atmospheric carbon dioxide."   So begins the directive from on high.  No, it is not Deity speaking; it is the opening salvo of the first of two Policy Forum articles devoted to the subject of Climate Change in the 29 September 2000 issue of Science magazine (Morgan, 2000; Baer et al., 2000).

The way the double-barreled commandment is presented, it sounds as if the exponential growth of atmospheric CO2 were a self-evident truth that can only be neglected at the peril of the world.  But is this claim factual?   Or is it just another example of the gospel of deceit?

A wise man once said that if you start right, you likely won't go wrong.   So let's investigate the validity of the opening statement of those who would give the world a new bureaucracy of unprecedented complexity along with the unprecedented power to enforce its edicts, i.e., the claim that the atmosphere's CO2 concentration is experiencing exponential growth.

Law Dome, AntarcticaIn the figure to the right, we have plotted the historical trend of the air's CO2 concentration from 1679 to 1978, as derived from an ice core extracted from Law Dome, Antarctica (Etheridge et al., 1998).  There it can be seen, as claimed by Morgan (2000), that the relationship described by the data does indeed appear to be of an exponential nature.  As time progresses, for example, the line through the data points curves evermore upwards.  Perhaps the best way to appreciate this fact is to lay a straightedge against the lower side of the curve to where it just touches it at one point and note that if you attempt to keep the straightedge "parallel" with the curve as you move to the right, it will have to be continually readjusted - slanted upward more and more - as you move across the graph.

Appearances, however, can often be deceiving; and inferences based upon appearances are even more tenuous.  Especially is this so when projecting exponential trends into the future.   They cannot go on forever, as they tend towards infinity, a state that cannot be reached by finite systems, such as the CO2 content of earth's atmosphere.

In view of this fact, it is extremely important to determine what is happening currently with respect to the air's CO2 content; and for this purpose we use the more exact record of atmospheric CO2 concentration derived from actual atmospheric measurements carried out in real time at Mauna Loa, Hawaii (Keeling and Whorf, 1998), which are updated on our website on an annual basis (see our Subject Index heading Carbon Dioxide: History - The Last 40 Years).

Law Dome DataThe graph to the right presents these data, which we have broken into two groups: the solid circles that run from 1959 to 1975 (1964 is omitted because of gaps in the data that year) and the open circles that run from 1976 to 1999.  If one examines the trends defined by these data, by moving a straightedge along the lower sides of the relationships they define, it is readily apparent that an upward curvature characteristic of an exponential relationship prevails over the initial time period (1959 to 1975), confirming what was learned from the first figure.  Over the second portion of the graph, however, no such curvature exists; the relationship is linear, i.e., it is described by a straight line.

It must be emphasized, however, that the relationships of this figure are highly tentative.   The initial exponential curve, in particular, must be considered very tenuous, because it is based on so few data - the solid circles - and, in fact, the open circles demonstrate that its projection into the future, i.e., beyond 1975, is indeed erroneous.   Likewise, the linear relationship defined by the open circles must also be viewed with caution when extrapolated into the future; for new data could alter its nature as well.  For the time being, however, we see that the "problem" we are being asked to get serious about - "the exponential growth of atmospheric carbon dioxide" - has not existed for the past quarter-century!

Nevertheless, the air's CO2 content continues to rise, but at a constant rate that results in future atmospheric CO2 concentrations being vastly lower than what would be the case with an exponentially-increasing CO2 concentration, as can be seen by observing how the future projections of the two relationships of the second figure deviate more and more from each other as time progresses.

But will this divergence continue?   It could; or it could reverse itself or expand even more.  Based on the historical record, however, we predict that the difference between the two projections of the second figure will become ever greater, simply because that is what has been happening over the last quarter-century.

But why should this be so?  There could be several reasons.  In our opinion, however, the change from the centuries-long exponential rise in the atmosphere's CO2 concentration to the past quarter-century's linear rate-of-rise is due to the ongoing rise in the air's CO2 content itself.   That is, we believe it is due to a negative feedback of the type that holds all sorts of phenomena in check and prevents physical and chemical conditions on earth from straying outside the range that is suitable for life's continued existence.

Very briefly, as the air's CO2 content continues to rise, its aerial fertilization effect stimulates earth's vegetation to grow ever more productively and profusely.  That is, the enhanced plant growth rates produced by atmospheric CO2 enrichment make earth's vegetation more productive; and the enhanced plant water use efficiency produced by atmospheric CO2 enrichment allows the planet's vegetation to grow in places that were previously too dry for it, thus increasing its profusion over the planet.  And these two phenomena - increased plant production and profusion - result in a much greater withdrawal of CO2 from the atmosphere, which consequently reduces the rate of rise of the air's CO2 content.

This scenario is described in considerably greater detail by Idso (1991a,b), who indicates that the rate of rise of the air's CO2 concentration may even begin to fall away from the linear rate that prevails presently, leading to a new equilibrium state with a higher-but-constant atmospheric CO2 concentration that supports a more vigorous and massive biosphere than exists at present.  Hence, rather than something to fret about and devise powerful global bureaucracies to attempt to prevent, the rising CO2 content of earth's atmosphere may well be our passport to a more prosperous planet, a place where our burgeoning population may exist at peace with a more productive world of nature.

So let's not jump to the conclusions that those who are clamoring for a host of global energy regulations and restrictions are trying to sell us, especially on the basis of the demonstrably false assumptions they portray as truth.   Their rush to judgment may not be to save the earth; it may be to hurriedly establish a global governing authority they have no hope of implementing in any other way, due to its onerous nature.  Time, which is running against them, will clearly tell who is correct, as the atmospheric CO2 record is beginning to show already.

Dr. Craig D. Idso
Dr. Keith E. Idso
Vice President

Baer, P., Harte, J., Haya, B., Herzog, A.V., Holdren, J., Hultman, N.E., Kammen, D.M., Norgaard, R.B. and Raymond, L.  2000.  Equity and greenhouse gas responsibility.  Science 289: 2287.

Etheridge, D.M., Steele, L.P., Langenfelds, R.L., Francey, R.J., Barnola, J.-M. and Morgan, V.I.  1998.  Historical CO2 records from the Law Dome DE08, DE08-2, and DSS ice cores.  In Trends: A Compendium of Data on Global Change.  Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, TN, U.S.A.

Idso, S.B.  1991a.  The aerial fertilization effect of CO2 and its implications for global carbon cycling and maximum greenhouse warming.  Bulletin of the American Meteorological Society 72: 962-965.

Idso, S.B.  1991b.  Reply to comments of L.D. Danny Harvey, Bert Bolin, and P. Lehmann.  Bulletin of the American Meteorological Society 72: 1910-1914.

Keeling, C.D. and Whorf, T.P.  1998.  Atmospheric CO2 concentrations - Mauna Loa Observatory, Hawaii, 1958-1997 (revised August 1998).  NDP-001.  Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, TN.

Morgan, M.G.  2000.  Managing carbon from the bottom up.  Science 289: 2285.