The following is a transcript of the Weather Break radio show for Friday, February 1, 2008. This episode was written by Dr. Jon Schrage.
On Monday's episode of Weather Break, we talked about mankind's ongoing desire to be able to not merely predict but actually control the weather and the climate of his environment. We now know that it isn't really possible to have some kind of "weather control satellite" or anything like that--the atmosphere is just too big and too complex to be able to regulate like that for human purposes. However, we DO know that humans are influencing the weather and climate of the earth all the time in inadvertent and complicated ways. The burning of fossil fuels is widely believed to be producing a large-scale warming of the planet through the enhancement of the greenhouse effect, for example. More subtly, changes in land use influence climate, too. For example, the so-called "urban heat island" is a well-known meteorological phenomenon in which large cities generally have higher temperatures than the surrounding countryside does. This is because the asphalt and pavement of cities use and store heat from the sun differently than the relatively moist soils and plants of the countryside do. Similarly, environmental scientists are studying the climate impact of deforestation in the tropical rain forests to see what impact the removal of these jungles has on the regional and global climate.
This idea that changes in the way land is used can cause changes in the weather and climate of a region sounds very modern, but actually it has been around for a long time. In fact, misunderstandings about the role of land use in climate change are a big part of the story of the settling of the Midwest and West by European and American settlers in the 19th century. At that time, the idea was called, "The Rain Follows the Plow".
As European and American settlers pushed farther and farther west across North America in the 1860s and 1870s, obviously they came across lands that were progressively less well-suited for the types of agriculture they were hoping to practice. Relatively moist farmlands of Illinois and Iowa were quickly claimed, while drier lands in Nebraska and South Dakota seemed too marginal to produce enough grain or grass for economically viable farms. Much of what we now call the High Plains had been labeled the "Great American Desert" by the first waves of settlers bound for California and Oregon, for example.
However, starting in the 1860s, rainfall started to increase in the High Plains, and word went back to the East Coast that maybe these semi-arid states WERE suitable for agriculture. Some unscrupulous land speculators, settlement promoters, railway men, and politicians began to promote this idea that somehow the arrival of large numbers of white settlers on the plains had caused the amount of precipitation in the region to increase. Amazingly, even some meteorologists and climatologists bought into this idea, coming up with elaborate--and, ultimately, wrong--ideas that somehow the turning of the sod by iron plows or the smoke from passing Union Pacific trains had somehow changed the climate. Actually, they didn't say "changed", they said "improved", and they really believed that somehow the "rain had followed the ploughs" up into the Great American Desert, bringing permanent prosperity to the region.
Unfortunately, the relatively moist times of the 1860s were not to last in the central United States. Drier times followed, with huge droughts following in the late 19th century. The lands of the High Plains could no longer economically support the relatively large populations that had settled here, and widespread hardships ensued.
Today we know that the idea that "the rain follows the plow" is one of the greatest discredited theories in meteorology, if not science overall. Not just in the United States but also in Australia and South Africa, residents misinterpreted a few moist years to mean that the climate had somehow permanently shifted to be more favorable for agriculture, and in all these cases the eventual return of drier conditions lead to economic collapse. Tragically, we now know that, if anything "drought follows the plouw", as we saw in the Dust Bowl years. Without careful management of water and soil resources, farming certainly CAN cause climate change, but generally not for the better.
