November 4, 2003
by Dennis T. Avery
The environmental movement is telling us that global warming might cause a mass extinction of wild species. This is a serious concern, since the Earth has clearly been warming for 150 years, either due to human activities or a natural cycle.
George Woodwell, a co-founder of the Environmental Defense Fund, said of global warming in 1989, “The changes expected are rapid enough to exceed the capacity of forests to migrate or otherwise adapt.” More recently, biologist Camille Root of Stanford University warned, “In my opinion, we’re sitting at the edge of a mass extinction.”
“The Specter of Species Extinction,” a new study published in September by the science-oriented Marshall Institute, concludes the opposite of Dr. Root—that global warming will bring more species diversity, not less, to most parts of globe. Rather than wiping out species, moderately warmer global temperatures will extend the ranges of thousands of plants and animals, enriching the diversity of most forests, mountains, and marine environments.
The Marshall report stresses that warmer temperatures give most trees, plants, animals, and fish the opportunity to extend their ranges toward the poles—without imposing any “heat limits” that would force them to give up the ranges they currently occupy. “The southern boundary of a tree’s natural range is not determined by temperature, but by competition between the northern species and more southerly-adapted species that have inherently greater growth rates.”
The Marshall researchers conclude that only over hundreds of years would the faster growing trees from the south be able to out-compete the already mature trees of the northern species. Forests and plants would only be able to shift their ranges northward and southward very slowly, giving the mammals, birds, fish, lichens, mushrooms, and other species that depend on the plant life ample time to shift with them.
Critical to the Marshall analysis is the reality that higher CO2 levels act as fertilizer for trees and plants, and that higher CO2 levels also reduce the amount of energy “wasted” by virtually all plant species on a process called photorespiration. As long as temperatures and CO2 are both rising, trees and plants will be vigorous enough to exploit warming’s opportunities to expand their range, rather than getting death notices from Greenpeace.
The Marshall Institute study reviewed the scary extinction predictions from two recent studies published in the journal Nature, one led by Stanford’s Dr. Root and the other led by Dr. Camille Parmesan of the University of Texas. The Marshall researchers found none of the 143 studies reviewed by the Stanford and Texas teams documented an extinction threat! The closest was the expansion of red foxes into the former range of arctic foxes in North America and Eurasia, forcing the arctic foxes farther north. But this is displacement, not extinction, unless the warming becomes so fierce that the arctic disappears altogether. (Obviously, this did not happen in either the Medieval Warming or the earlier Roman warming.)
The other studies reviewed covered a wide variety of species, from speckled wood butterflies to barnacle geese to Antarctic penguins to mountain flora in New Zealand and invertebrates in California’s coastal rocks. Most of the studies found increased species abundance and diversity, as would be expected from the mild, erratic and mostly-beneficial-to-wild-species warming we’ve had since 1850. (The Ice Ages are much harsher for both wild species and humans.)
“The Specter of Species Extinction” report was done by a father-and-sons research team, led by climate physicist Dr. Sherwood Idso, and his PhD sons, Craig (a specialist in climate geography) and Keith (a botanist who studies how plants respond to CO2 changes). Dr. Sherwood Idso, formerly of the U.S. Water Conservation Laboratory in Phoenix, AZ, was a winner of the U.S. government’s prestigious Arthur S. Flemming research award in 1977, and has published more than 500 articles in peer-reviewed publications. Dr. Craig Idso studied urban CO2 concentrations under a National Science Foundation Grant to Arizona State’s Office of Climatology. Dr. Keith Idso is a member of the Arizona Advisory Council on Environmental Education. All are on the staff of the Center for the Study of Carbon Dioxide and Global Change in Tempe, AZ.The Marshall Institute’s Board of Directors includes some the top scientific names of the twentieth century, including Dr. Bruce Aimes, recently awarded the National Medal of Science by President Clinton and Dr. Frederick Seity, former president of the National Academy of Science.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.
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