Revised to Reflect the Discussions at the U.S. Climate Forum

Regional Workshops:

The Southwest, Summer 1997

Rocky Mountains-Great Basin, Spring 1998

California, Spring 1998

What is the scope of this region? What are the primary characteristics of the geography and regional economy? This region includes California, Nevada, Utah, Arizona, New Mexico, Oregon, Idaho, Montana, Wyoming, and parts of Colorado. The arid nature of much of the West, combined with rapid population growth and increasing demand for water resources, means that this area is vulnerable to climate change and climate variability. The region's economy is a mixture of ranching, dryland and irrigated agriculture, tourism, retail, manufacturing, services, entertainment, and the high-technology industries. Much of the area is sparsely populated, contrasted with densely populated major metropolitan centers including Los Angeles, San Diego, San Francisco, Las Vegas, Salt Lake City, Denver, Phoenix, Tucson, Albuquerque, and other rapidly growing areas.

The region has the highest rate of population growth in the country, much of which is occurring in desert and semi-desert areas. Despite the vast areas with low population densities, the states in the region are among the most urbanized in the country in terms of the proportions of their populations in urban areas. Nevada is the most urban state in the country, for example, while Utah is the sixth. These urban and economic systems are in turn based on a rich mix of ecosystems including alpine mountain areas, deserts, forests, fertile valleys, riparian ecosystems, and coastal areas. All of these systems, human and natural, will potentially be effected by climate variability and change. A large portion of this land is publicly owned (overall, 50% of the West and as much as 85% of the state of Nevada). This makes federal and state government agencies responsible for managing the lands very important stakeholders.

What are current stresses on this region? Interannual climate is already extremely variable, and paleorecords show multi-decadal drought occurrences in the not-so-distant past. Water availability is among the top concerns in the region. Rapid population growth has greatly expanded urban water demands and has increased impacts on other key resources including air quality. The region's water use exceeds sustainable supply, and the demand at current prices is growing rapidly. Surface water supplies are insufficient, and groundwater use in many areas exceeds groundwater recharge rates, leading to the lowering of aquifer levels, contamination, and subsidence. In many parts of the region, agriculture, livestock, urban centers, tourism, and recreation are already faced with extreme pressures from the limits of water supplies. Ecological systems are particularly stressed due to water extractions from natural systems, and recent court and legislative mandates have directed that water be returned to these ecosystems to restore past damage.

Water "shortage" is a function of price and of its distribution over the water-using sectors. Between sixty and eighty percent of the water used in the Inter-mountain West and California goes to agriculture, and much of that on the basis of subsidized prices. One important policy issue is the impact of subsidies. If subsidies were removed and water were allocated on a market basis, some forms of agriculture would not be competitive and considerable volumes of water could be available for environmental needs and for urban and industrial uses. If, however, climate change brings more precipitation to the region, the supply would increase and "shortages" would diminish. The large seasonal, year-to-year, and decade-to-decade climate fluctuations have always had major impacts on ranching and agriculture. Analysis of climate records for the last century for a broad region of the Southwest (including Arizona, New Mexico, Nevada, and Utah) suggest that there has been a slight increase in both minimum and maximum temperatures, but no detectable change in precipitation.

In may parts of the West, land use patterns and the growing population have stressed natural ecosystems and increased the number of threatened and endangered species. Many of these species inhabit riparian, wetland, and aquatic ecosystems. As responses to climate variability and change are developed, the need to maintain adequate water flows in natural systems is an important consideration.

How might climate change and variability exacerbate or ameliorate these stresses? Future projections of climate in the Southwest (based on UKMO GCM and NCAR nested regional models) suggest that the Southwest could face significant climate changes in the next century: An increase in annual average temperatures of 5-9 degrees F. More extreme hot days, fewer cold days, and a decrease in daily temperature range. Decreased summer precipitation, and an increase in winter precipitation and its intensity.

Current biogeographical model simulations indicate up to a 200% increase in leaf area index in the desert southwest region of North America and a northern migration and expansion of arid-land species into the Great Basin region of North America. Landslides and debris flows in unstable Rocky Mountain areas and possibly elsewhere could become more common as winter wet precipitation increases. In California, important issues continue to include water supply and use, agriculture, forestry, coastal zones, protected areas, recreation, fisheries, land-use, and ports. There is a strong correlation between warm, dry weather patterns and fire frequency. Coupled with fuel accumulation in areas where human settlement has led to fire suppression, there is a strong likelihood that property damage and loss of human life will occur with greater and increasing severity under conditions of climate change.

One scenario predicts increased summer rain in the Great Basin. This would have mixed results. It would increase productivity of native vegetation, increase the amount of grasses in the shrub-steppe vegetation, and improve the situation for the livestock industry. But it could increase fire frequency (increased fuel, increased lightning strikes) which is a major cause of land degradation and reduced bio-diversity in the region. Another scenario predicts less snow accumulation and earlier run-off in the higher elevations. This would have a negative effect on the ski industry, various impacts on down-stream water users, and greater fire frequency in the higher elevations.

What are the most important information needs that have been identified? There is considerable demand for more and better climate information and climate change scenarios from various user communities. In particular, better extrapolations of scenarios to areas of complex topography are needed. The most critical need is for the best possible predictions for the region including scenarios for the mountain-basin topographies. These climate scenarios should include more regional land-use and cloud effects to reflect more realistic scenarios. For example, water supply agencies want winter precipitation forecasts 6-18 months in advance -- with clear discussion and communication of uncertainty included -- in order to manage storage systems and make commitments for water deliveries. There is a need for downscaled models that take into account the topography of the region and the annual monsoonal rainfall and seasonality of snowfall and melting.

Research is also needed to improve our understanding of how climate variability and change interact with economic markets and insurance, and how climate changes in other regions of the country and world affect the agriculture, ranching, industry, energy and other resource sectors. Finally, there is a need for regional centers that can provide and interpret information of regional significance.

What are possible coping strategies that have been identified? Policies relating to land-use and natural resources will require increased resilience to cope with increased variability in climate events. Construction in flood plains may need to be reconsidered, for example, and management of water resources may be influenced by changing patterns of precipitation. With a rapidly growing population in many parts of the West, a principal coping strategy during times of water shortages (and over the long-term as well) is to increase the efficiency of water use. Related improvements in energy efficiency will also contribute to reductions in greenhouse gas emissions. Discussions have included recommendations for increased use of mass transportation technologies and for reconsideration of land-use policies that reflect the carrying capacity of different areas. Greater societal education about climate and the consequences of climate change is a prerequisite for coping with anticipated effects.

Anticipation of more extreme events and preparation for them will likely be less expensive than strategies which simply pay for damages and clean up afterwards. One important aspect is the integration of better climate information and forecasts to adjust resource management to climatic conditions and to make appropriate adjustments, (e.g., for urban planning, livestock and wildlife management, agriculture, and energy production). Economic factors, including more accurate price signals, may need to be adjusted to provide mechanisms for change. Other considerations, such as the restructuring of water rights and pricing of water to allow for more flexible response of water demand and use to climate changes have been discussed. Monitoring and evaluation of climate and hydrologic variables, as well as ecological and socio-economic responses, will increase preparedness and adaptation to change.

In general, the short and long-term impacts of climate variability and change will require a reconsideration of existing policy structures. Institutional mechanisms that can help incorporate better scientific information and local knowledge about climate change and adaptive strategies (e.g., those of indigenous peoples and long-term residents) will be helpful in adaptation to change. Participation of a wide range of stakeholders in this process will assist in the development of new processes for the resolution of conflicts which might arise between competing uses and needs, particularly during times of shortages.