The evidence of impending climate change is now so overwhelming and incontrovertible that those who reject it can only be compared to flat-earthers and the handful of people who still insist that cigarettes don't really cause cancer. But if the remaining skeptics are right, improbable as it seems, then a massive international program to stop or reverse global warming would, in addition to being unnecessary, have adverse economic effects on the U.S. economy.
For present purposes, I'll assume—contrary to all the evidence—that human activity has negligible effects on natural processes that are producing rapid climate change. If that hypothesis were somehow proven true, I submit that there are other valid reasons for curtailing the emission of greenhouse gases, even if the earth's climate is evolving on its own in ways that we don't yet understand.
The reason: greenhouse gases are intimately associated with human activities that need to be restricted for other reasons having nothing to do with global climate change.
The primary greenhouse gas is carbon dioxide, though methane is a potent contributor as well (1). CO2 contributes anywhere from 9-26% of greenhouse gases, methane 4-9%, ozone 3-7% (2). Carbon dioxide is directly produced and consumed by living organisms through respiration, of course, but the following human activities are among the major causes of greenhouse gases and air pollution:
- Burning fossil fuels like oil and coal, which also produces particulates and soot, hydrocarbons, carbon monoxide, nitrogen oxides, sulphur dioxide, ozone and other air pollutants. Industrial societies are heavily dependent on polluting fossil fuels for everything from generating electricity to their transportation systems.
- Deforestation, including slash-and-burn agriculture that emits large volumes of CO2 into the atmosphere through fires and the gradual decay of wood. The loss of forest cover and vegetation also reduces the earth's ability to absorb CO2 through photosynthesis. Slash-and-burn agriculture also produces particulates, soot, carbon monoxide, sulphur dioxide and other pollutants. Urbanization is associated with concentrated pollution and the large-scale loss of wetlands, farmland, forests and vegetation cover.
- Livestock farming practices, including giant industrial hog farms, can produce methane and many noxious pollutants, from toxic wastes to foul odors.
- Giant landfills contribute methane and other greenhouse gases along with water pollution and noxious odors. They also consume large tracts of land and rely on the transportation grid to transport waste at great expense, often over large distances.
So, for example, a reduction in oil consumption would not only reduce greenhouse gases from that source; it would have numerous other benefits, including:
- A reduction in other forms of pollution such as particulates and soot, hydrocarbons, carbon monoxide, nitrogen oxides, sulphur dioxide and ozone.
- Less dependence on foreign sources of oil, which has led to various wars and interventions as countries act to protect their energy.
- Development of alternative energy sources that don't pollute.
- An improvement in the U.S. balance of trade deficit, which has increased in proportion to rising oil prices.
- The development of alternative transportation systems that are more efficient than urban freeways and less dependent on the automobile.
But, of course, it's not.
NOTES(1) Water vapor, not including clouds, causes 36-70% of the greenhouse effect on the earth's atmosphere. Human activity doesn't affect water vapor levels on a planetary scale.
(2) All these estimates are taken from Wikipedia's articles on greenhouse gases.
(3) Only the brain-dead would argue, for example, that particulates pose no health risk to humans or animals. Air quality here in the western U.S. is already being affected by upwind sources in China, whose growing economy generates vast quantities of soot, particulates and other aerosols.
(4) Last month I proposed a Car-Free Day for Oregon drivers as one baby step in the needed direction. Since the scope of this posting is relatively narrow, I'll defer until later any discussion of related issues like population growth, poverty and Third-World economic development.
GRAPH: Changes in global atmospheric concentration of carbon dioxide from 1870 to 2000.