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Rising Atmospheric CO2 Concentrations Reduce Soil Erosion: Lessons for the New Millennium
Volume 3, Number 25: 4 October 2000

Over the course of his career, our father has studied a vast array of subjects related to the ongoing rise in the air's CO2 concentration; and whenever he has gained sufficient insight into a topic, he has not been afraid to state his view of its implications for the future.

One of his more prescient predictions within the context of this multifaceted subject area concerns one of earth's most valuable natural resources - its soil.  Writing in his second book on the topic - Carbon Dioxide and Global Change: Earth in Transition (Idso, 1989) - our father stated that "as a result of the direct effects of atmospheric CO2 enrichment upon the primary plant processes of photosynthesis and transpiration ? many plants will greatly expand their ranges with augmented water use efficiencies, stabilizing the soil and protecting it from erosion."

This prediction went against the grain of nearly all thinking on the subject at the time it was made.  Starting in the 1970s and continuing almost to this day, study after study had concluded that soil erosion, via both wind and water, was running at a high sustained rate.   In fact, in a recent Policy Forum article in Science, Trimble and Crosson (2000) note that "some sources have suggested that recent erosion is as great as or greater than that of the 1930s," just as some sources are suggesting that global temperatures are greater now than they were in the 1930s (Crowley, 2000; Mann 2000).

If factual, this assessment would clearly refute the prediction of our father; for with the large increase in atmospheric CO2 concentration experienced over the past 70 years, one would surely have expected to see some positive consequences, i.e., reductions in soil erosion, by now, just as one would also have expected to see significant global warming by now, if predictions of that phenomenon were correct.  But herein lies the problem, or the solution to the problem, depending on one's point of view: this assessment is not factual, just as the highly-hyped global warming of the past seven decades is not factual either (see our editorials of 15 June, 1 July, and 15 July 2000).

The "remarkable feature" of the long-held belief in continued high, or even increasing, soil erosion, in the words of Trimble and Crosson, "is that it was based mostly on models," just as the global warming scare was (and still is!) based mostly on models.  Indeed, they state that "little physical, field-based evidence (other than anecdotal statements) has been offered to verify the high estimates," noting that "it is questionable whether there has ever been another perceived public problem for which so much time, effort, and money were spent in light of so little scientific evidence," which almost begs us to suggest that the "perceived public problem" of CO2-induced global warming is no different, and that it will soon outstrip the soil erosion problem in this regard, if it has not already done so.  But we digress; for the good news, according to Trimble and Crosson, is that "available field evidence suggests declines of soil erosion, some very precipitous, during the past six decades," which is exactly what would be expected on the basis of our father's prediction.

So what confused the issue for so many years?   The problem was largely a failure to realize that most of the soil particles removed from one part of the land, by either wind or water, were deposited in nearby areas, so that the net loss of soil was only a very small portion of that which was moved about by the forces of nature.

In reviewing this shift in our perception of U.S. soil erosion history, it is interesting to note that our perceptions of several ancillary phenomena may need some adjusting too.   Trimble and Crosson note, for example, that some studies have warned that "increasingly eroded soil profiles will allow less rainfall to be infiltrated and stored," leading to "increased overland flow, erosion, and flooding."   But as they further note, detailed hydrologic studies indicate that just the opposite is occurring: "runoff is decreasing, flood peaks are smaller, and in some places, the base flow is greater."  In addition, in their words, "these field studies show that more water is infiltrating into the soil and, in some cases, ? significantly more water is being transpired by plants."

These real-world observations are also what would be expected on the basis of our father's prediction.  With gradually increasing atmospheric CO2 concentrations gradually enhancing plant water use efficiencies, more plants should gradually be covering the ground, reducing rates of surface runoff and allowing more water to infiltrate into the soil, thereby providing more water to be extracted from the soil by more plants for subsequent transpiration into the air.

These hydrologic improvements, in turn, tend to improve the status of still other aspects of the planet's natural resource base, such as by increasing the stability of streams; and a good visual testament to the reality of this phenomenon is provided by a pair of photographs in the Trimble and Crosson article.  Both photos show the same view of a portion of Bohemian Creek, La Crosse County, Wisconsin.   The first, taken in 1940, shows an "eroded, shallow channel composed of gravel and cobbles, with coarse sediment deposited by overflows on the floodplain."   The second, taken a quarter of a century later in 1974, shows that the stream channel "is narrower, smaller, and more stable."  Also, "the coarse sediment has been covered with fine material, and the flood plain is vegetated to the edge of the stream."   What is more, the authors note that conditions improved even more over the following 25 years.

In reviewing these many real-world manifestations of the benefits of the ongoing rise in the air's CO2 concentration for our nation's (and the world's!) important soil and water resources, we are gratified that our father had the courage to speak out on this subject as he did in his 1989 book, as well as in his earlier book (Idso, 1982).  We also hope that the lesson taught by Trimble and Crosson, about the "myth and reality" of U.S. soil erosion history, will not be lost on those currently struggling with the reality of rising atmospheric CO2 concentrations and the myriad myths that have been associated with this phenomenon, such as catastrophic global warming and its attendant host of soon-to-be-experienced horror stories.

In conclusion, we agree wholeheartedly with Trimble and Crosson, who rightly state in the concluding paragraph of their important Policy Forum article that "no problem of resource or environmental management can be rationally addressed until its true space and time dimensions are known," something which has yet to be achieved in the climate change arena.  And we agree even more wholeheartedly - if such is possible - with their conclusion that "the uncritical use of models is unacceptable as science and unacceptable as a basis for national policy."   Unfortunately, many nations of the earth have yet to learn this lesson; and if they do not learn it soon, we could all very shortly find ourselves in a world of economic hurt, brought on by our own naivety.

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

Crowley, T.J.  2000.  Causes of climate change over the past 1000 years.  Science 289: 270-277.

Idso, S.B.  1982.  Carbon Dioxide: Friend or Foe? An Inquiry into the Climatic and Agricultural Consequences of the Rapidly Rising CO2 Content of Earth's Atmosphere.  IBR Press, Tempe, AZ.

Idso, S.B.  1989.  Carbon Dioxide and Global Change: Earth in Transition.  IBR Press, Tempe, AZ.

Mann, M.E.  2000.  Climate change: Lessons for a new millennium.  Science 289: 253-254.

Trimble, S.W. and Crosson, P.  2000.  U.S. soil erosion rates - myth and reality.  Science 289: 248-250.