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Why does the horizon of mineral reserves never seem to go out further than a few decades? Basically because miners and technologists do not find it worthwhile to find new sources and develop new production techniques until markets signal that they are needed. How this process evolves is encapsulated by the USGS report which notes that in 1970 known world copper reserves stood at “about 280 million metric tons of copper. Since then, about 400 million metric tons of copper have been produced worldwide, but world copper reserves in 2011 were estimated to be 690 million metric tons of copper, more than double those in 1970, despite the depletion by mining of more than the original estimated reserves.”
Environment: In most of the Limits model runs, the ultimate factor that does humanity in is pollution. In their model pollution directly increases human death rates and also dramatically reduces food production. In fact, as the world economy has grown, global average life expectancy has increased from 52 years in 1960 to 70 years now. It must be acknowledged that globally, pollution [PDF] from industrial and agricultural production continues to rise. But the model assumed that pollution would increase at exponential rates. However, many pollution trends have not increased exponentially in advanced countries.
Consider that since 1970, the U.S. economy has grown by 200 percent, yet the levels of air pollutants [PDF] regulated by the federal government have fallen by nearly 60 percent. For example, in both the U.S. and the European Union [PDF] sulfur dioxide emissions have dropped by nearly 70 percent since 1990. Recent data suggests that sulfur dioxide emissions even from rapidly industrializing China peaked in 2006 [PDF] and have begun declining. Earlier studies cite evidence for a pollution turning point income threshold (purchasing power parity) of around $10,000 [PDF] for demands to reduce this form of air pollution.
Another pollution concern was world fertilizer consumption that by 1970 had increased five-fold since World War II to 50 million tons. The Limits analysts noted that fertilizer consumption was growing exponentially “with a doubling time of ten years.” The concern was the excess fertilizer running off of farms pollutes rivers, lakes, and the oceans. Presumably this doubling time suggests that since 1970, global fertilizer use should have increased to 400 million tons today. In fact, global fertilizer use is currently 150 million tons [PDF]. Around 1980 U.S. annual fertilizer use stabilized at around 20 million tons, yet U.S. agricultural yields have more than doubled since then.
Although, the Limits model measure for what counted as “pollution” was quite vaguely commodious, the Australian researcher Turner decides to use in his analysis carbon dioxide emissions from fossil fuels as his chief pollutant. The Limits analysis was actually pretty good at projecting atmospheric concentrations of carbon dioxide.
However, a recent Reason Foundation study reported [PDF] that the U.N.’s Intergovernmental Panel on Climate Change own analyses find that the scenario in which future temperatures increase the most is also the same world in which the greatest amount of wealth creation occurs. The result is that “by 2100 GDP per capita in poor countries will be double the U.S.’s 2006 level, even taking into account any negative impact of climate change.” This means more technology and wealth will be available to cope with any problems that may occur from climate change.
One of the odder features of the Limits computer model is that it basically ignores one of the most robust feedback mechanisms in the world—markets and price systems. The modelers warn against placing our faith in the technological solutions, pointing to the collapse of the whaling industry as an example. They argue that improvements in whaling technology ended up destroying that industry. They completely overlook the fact that whaling occurred in an open access commons in which everyone has incentive to kill as many whales as possible to make sure that their competitors didn’t benefit from them. Similarly, today wherever one identifies an environmental problem, one can be sure that it is occurring in the moral equivalent of an open access commons. In fact, the depletion of whales and rising price of whale oil encouraged entrepreneurs to seek new form of lighting; in this case, turning gooey crude oil into kerosene.
A lot of the data over the last 40 years fails to confirm the model’s projections. But only time will tell if The Limits to Growth computer model is a true case of “pessimism in” generating “pessimism out.”
Ronald Bailey is Reason's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books