Climate Variability and Change in the Southwest

Part III: Workshop: Sectoral Issues

Workshop report prepared by:

Mark Patterson, Graduate Research Associate
Udall Center for Studies in Public Policy
The University of Arizona
Tucson, AZ

Workshop Participants: Linda Mearns (facilitator), David Brabec, Mette Brogden, Fred Fisher, Robert Gerard, Bruce Kimball, Peter Kuch, Claudia Nierenberg, Maurice Roos

Impacts and Vulnerabilities

Of all the uses of water in the Southwest, agriculture is by far the largest user, consuming almost 80 percent of the annual available water. Given this large dependence on water, the agricultural sector in the arid Southwest is particularly vulnerable to climate variability.

Agriculture is heavily dependent on irrigation, as "rainfed" agriculture is limited given the precipitation regimes of the Southwest. Specific crops that are most vulnerable to climate change include cotton, wheat, alfalfa, vegetables, and orchard crops.

Cotton production in the Southwest is the largest agricultural user of water, and while cotton appears to be more tolerant to higher temperatures, the most productive varieties require the most water. Cotton production is declining in the Southwest, in part owing to decreases in national and international prices.

Wheat production on the other hand is gaining momentum, but recent climate-related pest infestations have caused some setbacks and threaten farmers' confidence.

Vegetables such as tomatoes and lettuce are of high value, but require high inputs.

Each crop type requires different irrigation schedules, and deviance from established schedules can be potentially disastrous.

Smaller farms in the Southwest are not flexible in terms of capital, but are able to adapt more readily in the face of increased vulnerability. Organic farmers, however, are more susceptible to the consequences of climate change.

Manifestations of climate change such as mild winters and hot humid summers often impact crops in terms of pest and mold problems. Another indirect impact from climate change is increase soil salinity caused by an increase in evaporation. In general climate-change vulnerability is geographically and problematically diverse.

Responses

The agricultural sector's response to climate variability has been slow and varied. Extensive capital investment in crop-specific farm machinery has many farmers reluctant to change crop types. The flexibility to change crop type is an important factor in decisionmaking. Several farmers for example, have switched from corn to sorghum.

Another response to climate variability by the agricultural sector has been to sell farms and their accompanying water rights to growing cities. (Water rights in the Southwest are tied to land ownership.) In Arizona, the city of Tucson has purchased farmland in nearby Avra Valley while Phoenix has acquired farms as far away as Yuma, several-hundred miles away.

These climate variability-induced water transfers have an indirect impact on the local tax base for governments, as cities are exempt from paying taxes to these local governments. While some farmers believe that too much agricultural land is being lost to residential development, others feel that the trend is passing as the costs of distribution systems are being spread over fewer people.

Research and Information Needs

Increased climate variability is the most difficult aspect of climate change for farmers as it introduces more uncertainty into a farmer's decisionmaking. The planning range for farmers in the Southwest may be a long as ten years.

Adaptation to change is slow and expensive. Farmers require both long term (decadal) and short term (seasonal) forecasts.

Timing and intensity of precipitation, temperature (minimum and maximum), and cloud cover and radiation intensity are critical factors in seasonal planting decisions, while longer-term climatological information is important for selecting crop types.

Stakeholders have identified the following areas in which research and information is required to adapt more effectively to climate variability

• the availability of water for controlled irrigation
• the foreknowledge of pest infestation
• the diurnal temperature range and
• more assistance from Cooperative Extension and outreach services

Scientists, on the other hand, view research on the relationships among CO₂, temperature and water budgets as more urgent.

Policy Issues

The most pressing policy issue identified by stakeholders is that of water management and rights. Stakeholder views vary on whether the existing policies are flexible enough to accommodate climate changes and subsequent impacts.

All agreed however, that urban development on previously agricultural land and the purchase of "water farms" are serious matters. Water policies need to be broadened to consider indirect impacts of climate change such as the erosion of the tax base in rural areas and the economic diversity of the Southwest.

For additional discussions on this topic, see the presentations for Panel 3: Ranching and Agriculture, in Chapter 8.