Global warming could prove to be a major limiting
factor to economic and population growth in Texas. From 1950 to 1956 Texas
experienced a drought so severe that 94 percent of its counties were declared
national disaster areas. Since then the state has nearly doubled in population
and has depleted much of its groundwater. Add to that projections of another
doubling of population in 50 years, and scientists’ predictions that the
earth’s temperature will increase by eight degrees over the next century, and
you have a potential recipe for disaster.
In 1991 the Texas Water Development Board (TWDB)
funded
a research team, headed by Jurgen Schmandt of UT’s LBJ School of Public
Affairs, to study the effects of future global warming on Texas’ water supply.
Schmandt’s report notes that even at current population levels, a repeat of the
drought conditions of the early 1950s would create serious water shortages in
many parts of the state, notably the Rio Grande Valley and areas dependent on
the Edwards Aquifer. A conservative estimate of a 3.5 degree warming by 2030,
along with a five percent reduction in rainfall, could create crisis situations
in some areas of the state.
The Rio Grande is particularly vulnerable. Since the
upper Rio Grande has been sucked dry by cities and farms by the time it leaves
El Paso, the lower Rio Grande is 70 percent dependent on flow from Mexican
rivers. An ongoing two-year drought in northern Mexico has already dropped the
Falcon and Amistad reservoirs on the Rio Grande to dangerously low levels. In
Mexico, 200,000 cattle have died in recent months because of the drought, and
more than a million acres of crops may go unharvested. Scientists believe that
a three- to four-degree average temperature increase would push the Chihuahuan
Desert 200 miles northward into much of the drainage basin of the Colorado
River in West Texas. Last summer, record-breaking temperatures of up to 114
degrees scorched the area.
Unlike the Rio Grande, which originates from Rocky
Mountain snow melt, The 600-mile Colorado is totally dependent on Texas
rainfall. Schmandt predicts that by 2030, reservoirs in the upper Colorado
would be depleted by the sixth year of a drought comparable to that of the
1950s. Highland Lakes levels would be dangerously low at only 30 percent of
capacity, and recreation and irrigation would be curtailed.
Ironically, besides drought, another anticipated
effect
of global warming is an increased incidence of hurricanes and flooding. In
addition, if the polar ice caps begin to melt, Gulf Coast sea levels are
projected to rise three to four feet, making Houston and Galveston even more
vulnerable to flooding from hurricanes or heavy rain, contaminating coastal
aquifers with seawater, and destroying bay and estuary ecosystems. Farther
inland, droughts could be interspersed with flashflooding from heavy storms off
the Gulf. River authorities would be subject to conflicting needs to preserve
the runoff in reservoirs to meet future water demand, and to release water
gradually to prevent disasterous downstream flooding.
Hotter temperatures would also increase air
conditioner use, especially in the booming metroplexes, where acres of asphalt
soak up heat during the day and release it at night to produce the “urban heat
island effect.” Increased electricity use would fuel demand for water flow to
provide power for hydraulic electric plants. As Schmandt’s report
concludes,”Water shortages call into question the feasibility of continued
long-term population growth and economic expansion.” –
N.E.
This article appears in June 2 • 1995 and June 2 • 1995 (Cover).