EPA tries to hogtie Wyoming

Published August 1, 2000

We hear from EPA’s “State and Local Climate Change Outreach Kit” that Wyoming’s temperatures could rise by 11°F in winter over the next 100 years, with devastating consequences.

Seems they’d have us believe that Laramie, which warmed 1.5°F in the last century, could one day become a ghost town as higher temperatures endanger public health and lower snowfalls make water a scarcity.

Perhaps most alarming for Wyoming’s agricultural industry, EPA claims dryland hay and pasture yields could fall by 13 percent in the future. That would be a rough ride indeed. Wyoming, after all, is ranching country, with 80 percent of its production agriculture coming from livestock, mostly cattle.

But there’s no need to circle the wagons just yet. EPA’s prediction is at odds with hundreds of articles showing that increased carbon dioxide (CO2) will make forage crops grow bigger and faster and more resistant to drought, pests, disease, and other stresses. And studies continue to confirm that grasslands prosper as CO2 rises.

For instance, Greer and colleagues in cattle-rich New Zealand grew five different pasture grass species at various temperatures and CO2 concentrations, at both full light and 70 percent shade. They found that “Response to CO2 was highest at 28°C for all species and significantly lower at 18°C” and “Photosynthetic responses to CO2 were consistently higher for all species at 28 than at 18°C.” Contrary to EPA expectations, they found pastures thrive when higher temperatures are combined with higher CO2.

In an earlier study, Niklaus and colleagues grew swards from a calcareous grassland for two years in greenhouses with atmospheric CO2 of 350 ppm and 600 ppm. Only half the sections received phosphorous fertilizer. After four years of elevated CO2 in the natural field conditions, the grassland biomass had increased by 25 percent. Elevated CO2 also improved the plants’ nitrogen- and phosphorous-use efficiency. Throughout the study, the Niklaus team found that the leguminous species received more of a boost from CO2 than the nonleguminous species.

As for those pesky weeds, which can crowd out more nourishing plants, Leishman and researchers grew four common European weeds with atmospheric CO2 concentrations of 350 ppm and 550 ppm. Unlike for grass, elevated CO2 did not significantly affect the growth or reproductive success in three of the four species.

Scaring the environmental greenhorns with outrageous climate predictions is, as they say in the West, lowdown and yellow-bellied. And as the scientific literature reminds us time and again, the junior cowpokes of today will grow up to witness some amazing biological benefits as CO2 continues to rise.

Robert C. Balling Jr., Ph.D. is director of the Laboratory of Climatology at Arizona State University and coauthor of The Satanic Gases.


Greer, D.H., et al., 2000. The effect of perturbations in temperature and photon flux density on the growth and photosynthetic responses of five pasture species to elevated CO2. Australian Journal of Plant Physiology, 27, 301-310.

Leishman, M.R., K.J. Sanbrooke, and R.M. Woodfin, 1999. The effects of elevated CO2 and light environment on growth and reproductive performance of four annual species. New Phytologist, 144, 455-462.

Niklaus, P.A., et al.,1998. Nutrient relations in calcareous grassland under elevated CO2. Oecologia, 116, 67-75.