Texas and the Southern Great Plains

Overview
Rapid changes in the economy, population, and building technologies have dramatically reshaped the nature of weather and climate impacts in Texas and surrounding states.  In the 1950’s and 1960’s drought impacts on water supply and agriculture were a serious hazard and large-scale threat to the Texas economy.  Today the population of the state is concentrated in urban areas and the system of agricultural production is less vulnerable to drought.  Irrigation technologies, agribusiness consolidation, and integration into a regional and global food supply system have reduced some of the direct and indirect impacts of drought on the economy and employment. However, groundwater resources from the Ogallala Aquifer are drawn down at faster rates in some areas of Texas than precipitation and runoff can replenish them. In addition, while threats to the food supply have diminished, other threats related to weather and climate hazards have become more severe. For example, the combination of sea level rise and growth of coastal populations has increased the potential for serious damage associated with hurricanes. Thus, the National Assessment and other scientific research currently under way conclude that climate variability and change pose significant risks to urban water supplies, coastal resources, and air quality in the region. This summary provides details from these ongoing efforts.

Climate projections for Texas and the Southern Great Plains
In the Southern Great Plains, the 20th century temperature record shows no consistent trend, except that in some areas winters and springs have experienced greater seasonal warming, a trend that is expected to continue with global warming. In addition, areas of the Southern Great Plains have already experienced significantly more high intensity rainfall, which is also expected to accompany global warming.
Current climate models project significant regional temperature increases by 2100, with especially high increases in the average summer heat index (which combines temperature and humidity). Models also project a greater number of heat waves – three days in a row above 90ºF – which cause heat stress for people and livestock. 
Projected changes in precipitation are bigger in the Canadian climate model than in the Hadley Centre model, with decreases of up to 25% in an area including the Oklahoma panhandle and northern Texas. Other areas might actually see slight increases. However, increased evaporation due to rising air temperatures are thought to result in net soil moisture declines, thus negatively affecting farming and ranching. 

Key Findings

Will there be water for Texas cities?
The vulnerability of both water supply and water quality to drought remains a serious issue that could be significantly enhanced by climate warming.  The most serious consequences of future droughts will be experienced in metropolitan areas and low-income rural populations.  Populations living along the Texas-Mexico border are especially vulnerable due to extremely high levels of poverty, lack of infrastructure for water supply and sanitation, and poor access to social services.  Both groundwater and surface water supplies along the border region are endangered by demands that exceed supply and by multiple sources of contamination that increase during periods of drought.  Existing legal and institutional mechanisms to deal with the consequences of drought are insufficient already and likely to be wholly inadequate in an era of more frequent or intense climate variability.  

Sea-level rise increases the risk of coastal disasters
Sea level is rising along the Texas coast due to global sea-level rise and local subsidence.  Most people living along the coast are aware of the related coastal hazards from recent experience with hurricanes, floods and coastal erosion. However, life along the coast offers some escape from the hotter inland areas, which suggests that climate warming could accelerate coastal development.  The deadliest hurricane of the 20th century caused enormous loss of life and property in Galveston, Texas. In recent years, severe hurricanes have been less frequent along the Texas coast, but the risk of significant damage due to coastal flooding and erosion has increased due to relative sea-level rise and a continuing movement of people and wealth into low-lying areas adjacent to coastal waters. For example, Tropical Storm Frances in 1998 caused severe erosion and extensive property damages in Galveston County. These trends portend a significant increase in coastal property losses and reconstruction costs in future years whether or not tropical storms increase in frequency or intensity.  
The location of 23% of U.S. oil refining capacity along the Texas coastline is a “wild card” in the suite of possible weather and climate impacts.  The effects of continuing sea-level rise combined with storm surges associated with tropical storm events could shut down or damage an important component of America’s refining capacity.  A prolonged reduction in refining capacity would damage both the local and national economy.  In addition, other research shows how coastal erosion poses a significant threat to the Gulf Intracoastal Waterway – a transportation backbone of regional and national significance. Continued commitment to channel protection is required to avert erosion-related interruption of transportation and trade.
Other important economic and ecological assets in harm’s way along the Texas coast include the Ports of Houston, Corpus Christi, and Brownsville and ecological treasures like the Padre Island National Seashore and Laguna Madre.  The Laguna Madre is an ecologically unique coastal embayment at the Texas-Mexico border, jointly managed by Mexico and the US.  Coastal flooding and/or flooding in the Lower Rio Grande river watershed could wash large amounts of contaminated material from industrial and agricultural sources into this sensitive ecosystem.  High poverty levels leave this region ill-prepared to mitigate or manage the potential impacts of both extreme weather events or long-term climate change.

Will the Texas air crisis worsen?
Most large metropolitan areas in Texas currently face an air pollution crisis.  Millions of Texans live in unhealthy air.  Houston, the fourth largest city in the U.S., has become the smog capitol of the nation. High temperatures enhance the formation of ground-level ozone and other toxic chemicals associated with smog. Global warming will increase the length of the already long smog season in Texas.  Increasing temperatures will also increase the demand for air conditioning, which will increase the use of electricity, with consequent increases in emissions of smog-forming gases from fossil fuel power plants.  The health and legal consequences of the failure of major Texas cities to comply with federal air quality standards are a serious threat to the future human and economic health of the state and region.

Adapting to the Potential Impacts of Global Warming
 

Climate scientists agree that further climate change may be inevitable and will therefore require adaptation, although most scientists also think that the pace of climate change can be slowed by substantially reducing greenhouse gas emissions. This would give governments, businesses, and ecosystems around the world more time to respond and adapt to climate change as well as reducing the overall severity of climate change-related impacts, thereby buying "insurance" for an uncertain future.  Another way to buy insurance now is to incorporate climate change into all long-term decisions about natural resources, thereby providing greater resilience.

Reducing vulnerability to the severe water shortages that may occur in a warmer world will require an acceleration of efforts to improve the efficiency of use of irrigation water in agriculture and reductions in urban water demand through vigorous conservation and efficiency initiatives.  Preliminary experiments with the pricing and marketing of water also show great promise for enhancing the sustainability of future water supplies.
Texas’ recent efforts to address the state’s coastal erosion problems will likely need to be extended in the future, and require either a long-term financial commitment to protect developed eroding areas, and/or a strict implementation of existing coastal laws that require retreat from the eroding shoreline when structures come to be located on the public beach.
Likewise, efforts to set air pollution standards and to monitor and enforce measures to reduce air pollution will need to be continued and strengthened.

Additional Information

For more detailed information, the following expert is available to answer your questions:

Dr. Robert Harriss, Chair of the Southern Great Plains Workshop Steering Committee, 
National Center for Atmospheric Research, Boulder, CO
  Tel: (303) 497-8106; E-mail: harriss@ucar.edu; Web: http://www.esig.ucar.edu

Dr. Susanne Moser, Staff Scientist, Union of Concerned Scientists
  Tel.: (617) 547-5552; E-mail: smoser@ucsusa.org