Time Tunnel Points to Future in High CO2
By Don Comis
December 27, 1999
Higher carbon dioxide levels in the
atmosphere may be partly responsible for a worldwide increase in the
displacement of grasslands by mesquite and other brushy weeds.
The rise in CO2 levels matches this increase in brush--and the progress of
the Industrial Age.
That observation led U.S. Department of
Agriculture scientists to build a "time tunnel" three years ago.
It's actually two plastic-walled tunnels, with rangeland plants growing inside
them. One tunnel goes from today's CO2 level of 350 parts per million to 2050's
predicted 550 ppm. The second tunnel goes from the Ice Age level of 200 ppm to
A tunnel study last year showed that higher CO2 levels caused plants to grow
faster and use water more efficiently. This suggests that higher CO2 levels
might be speeding brush invasions by allowing plants like mesquite to thrive on
Ecologists H.Wayne Polley and Hyrum B. Johnson, with USDA's Agricultural
Research Service at the Grassland Soil and
Water Research Laboratory at Temple, Tex., did the study with colleagues at
ARS and the Texas Agricultural Experiment
Station at Temple. ARS is the chief scientific arm of the U.S. Department
The time tunnel research is described in a special feature on the future of
ARS natural resources research in the current millennium edition of ARS' Agricultural Research magazine.
Click here to
view the time-tunnel story on the web.
Scientific contact: H. Wayne Polley, ARS
Grassland Soil and Water Research
Laboratory, Temple, Tex., phone (254) 770-6629, fax (254) 770-6561,