Our study calculates the estimated difference in water use, energy demands, and CO2 emissions of head lettuce associated with the production (land preparation and growing operations, chemical inputs, irrigation) and the transportation (diesel demand) to the Phoenix metro area from:
       1. A local level, defined here as within Maricopa County, Arizona (AZ).
       2. From the central coast of California (CA) in Monterey County.

Our research results demonstrate that local lettuce is more resource intensive than non-local or regional produce. Production in Maricopa County has significantly higher (more than double) energy demands and emissions than Monterey County. Irrigation and chemical inputs are the greatest contributors to energy demand in Maricopa, but it is primarily irrigation that contributes to emissions. Comparatively, transportation and chemical inputs are the greatest contributors to energy demand in Monterey, and it is primarily transportation that contributes to emissions.

This life cycle inventory suggests that we need to reconsider the “food miles” framing of the local food debate and whether local food production is a viable sustainable alternative to the current food system in the arid Southwest. However, we also recognize that factors beyond resource-use and emissions affect policymakers’ and consumers’ demands for local foods. Future studies ought to provide a more nuanced look at the issue that also includes social, psychological, and economic factors that influence food policies and purchases. These results have important implications for future water management and suggest the need to pursue more water efficient practices in AZ.

In recent years, concerns have grown over the risks posed by climate change on the U.S. electricity grid. The availability of water resources is integral to the production of electric power, and droughts are expected to become more frequent, severe, and longer-lasting over the course of the twenty-first century. The American Southwest, in particular, is expected to experience large deficits in streamflow. Studies on the Colorado River anticipate streamflow declines of 20-45% by 2050. Other climactic shifts—such as higher water and air temperatures—may also adversely affect power generation. As extreme weather becomes more common, better methods are needed to assess the impact of climate change on power generation. This study uses a physically-based modeling system to assess the vulnerability of power infrastructure in the Southwestern United States at a policy-relevant scale.

Thermoelectric power—which satisfies a majority of U.S. electricity demand—is vulnerable to drought. Thermoelectric power represents the backbone of the U.S. power sector, accounting for roughly 91% of generation. Thermoelectric power also accounts for roughly 39% of all water withdrawals in the U.S.—roughly equivalent to the amount of water used for agriculture. Water use in power plants is primarily dictated by the needs of the cooling system. During the power generation process, thermoelectric power plants build up waste heat, which must be discharged in order for the generation process to continue. Traditionally, water is used for this purpose, because it is safe, plentiful, and can absorb a large amount of heat. However, when water availability is constrained, power generation may also be adversely affected. Thermoelectric power plants are particularly susceptible to changes in streamflow and water temperature. These vulnerabilities are exacerbated by environmental regulations, which govern both the amount of water withdrawn, and the temperatures of the water discharged. In 2003, extreme drought and heat impaired the generating capacity of more than 30 European nuclear power plants, which were unable to comply with environmental regulations governing discharge temperatures. Similarly, many large base-load thermoelectric facilities in the Southeastern United States were threatened by a prolonged drought in 2007 and 2008. During this period, the Tennessee Valley Authority (TVA) reduced generation at several facilities, and one major facility was shut down entirely. To meet demand, the TVA was forced to purchase electricity from the grid, causing electricity prices to rise.

Although thermoelectric power plants currently produce most of the electric power consumed in the United States, other sources of power are also vulnerable to changes in climate. Renewables are largely dependent on natural resources like rain, wind, and sunlight. As the quantity and distribution of these resources begins to change, renewable generation is also likely to be affected. Hydroelectric dams represent the largest source of renewable energy currently in use throughout the United States. Under drought conditions, when streamflow attenuates and reservoir levels drop, hydroelectric plants are unable to operate at normal capacity. In 2001, severe drought in California and the Pacific Northwest restricted hydroelectric power generation, causing a steep increase in electricity prices. Although blackouts and brownouts were largely avoided, the Northwest Power and Conservation Council estimated a regional economic impact of roughly $2.5 to $6 billion. In addition to hydroelectric power, it has also been theorized that solar energy resources may also be susceptible to predicted increases in surface temperature and atmospheric albedo. One study predicts that solar facilities in the Southwestern U.S. may suffer losses of 2-5%.

The aim of this study is to estimate the extent to which climate change may impact power generation in the Southwestern United States. This analysis will focus on the Western Interconnection, which comprises the states of Washington, Oregon, California, Idaho, Nevada, Utah, Arizona, Colorado, Wyoming, Montana, South Dakota, New Mexico and Texas. First, climactic and hydrologic parameters relevant to power generation are identified for five types of generation technologies. A series of functional relationships are developed such that impacts to power generation can be estimated directly from changes in certain meteorological and hydrological parameters. Next, climate forcings from the CMIP3 multi-model ensemble are used as inputs to a physically-based modeling system (consisting of a hydrological model, an offline routing model, and a one-dimensional stream temperature model). The modeling system is used to estimate changes in climactic and hydrologic parameters relevant to electricity generation for various generation technologies. Climactic and hydrologic parameters are then combined with the functional relationships developed in the first step to estimate impacts to power generation over the twenty-first century.

This LCA used data from a previous LCA done by Chester and Horvath (2012) on the proposed California High Speed Rail, and furthered the LCA to look into potential changes that can be made to the proposed CAHSR to be more resilient to climate change. This LCA focused on the energy, cost, and GHG emissions associated with raising the track, adding fly ash to the concrete mixture in place of a percentage of cement, and running the HSR on solar electricity rather than the current electricity mix. Data was collected from a variety of sources including other LCAs, research studies, feasibility studies, and project information from companies, agencies, and researchers in order to determine what the cost, energy requirements, and associated GHG emissions would be for each of these changes. This data was then used to calculate results of cost, energy, and GHG emissions for the three different changes. The results show that the greatest source of cost is the raised track (Design/Construction Phase), and the greatest source of GHG emissions is the concrete (also Design/Construction Phase).

As average temperatures and occurrences of extreme heat events increase in the Southwest, the water infrastructure that was designed to operate under historical temperature ranges may become increasingly vulnerable to component and operational failures. For each major component along the life cycle of water in an urban water infrastructural system, potential failure events and their semi-quantitative probabilities of occurrence were estimated from interview responses of water industry professionals. These failure events were used to populate event trees to determine the potential pathways to cascading failures in the system. The probabilities of the cascading failure scenarios under future conditions were then calculated and compared to the probabilities of scenarios under current conditions to assess the increased vulnerability of the system. We find that extreme heat events can increase the vulnerability of water systems significantly and that there are ways for water infrastructure managers to proactively mitigate these vulnerabilities before problems occur.

Recent developments in computational software and public accessibility of gridded climatological data have enabled researchers to study Urban Heat Island (UHI) effects more systematically and at a higher spatial resolution. Previous studies have analyzed UHI and identified significant contributors at the regional level for cities, within the topology of urban canyons, and for different construction materials.

In UHIs, air is heated by the convective energy transfer from land surface materials and anthropogenic activities. Convection is dependent upon the temperature of the surface, temperature of the air, wind speed, and relative humidity. At the same time, air temperature is also influenced by greenhouse gases (GHG) in the atmosphere. Climatologists project a 1-5°C increase in near-surface air temperature over the next several decades, and 1-4°C specifically for Los Angeles and Maricopa during summertime due to GHG effects. With higher ambient air temperatures, we seek to understand how convection will change in cities and to what ends.

In this paper we develop a spatially explicit methodology for quantifying UHI by estimating the daily convection thermal energy transfer from land to air using publicly-available gridded climatological data, and we estimate how much additional energy will be retained due to lack of convective cooling in scenarios of higher ambient air temperature.

Sustainable mobility policy for long-distance transportation services should consider emerging automobiles and aircraft as well as infrastructure and supply chain life-cycle effects in the assessment of new high-speed rail systems. Using the California corridor, future automobiles, high-speed rail and aircraft long-distance travel are evaluated, considering emerging fuel-efficient vehicles, new train designs and the possibility that the region will meet renewable electricity goals. An attributional per passenger-kilometer-traveled life-cycle inventory is first developed including vehicle, infrastructure and energy production components. A consequential life-cycle impact assessment is then established to evaluate existing infrastructure expansion against the construction of a new high-speed rail system. The results show that when using the life-cycle assessment framework, greenhouse gas footprints increase significantly and human health and environmental damage potentials may be dominated by indirect and supply chain components. The environmental payback is most sensitive to the number of automobile trips shifted to high-speed rail, and for greenhouse gases is likely to occur in 20–30 years. A high-speed rail system that is deployed with state-of-the-art trains, electricity that has met renewable goals, and in a configuration that endorses high ridership will provide significant environmental benefits over existing modes. Opportunities exist for reducing the long-distance transportation footprint by incentivizing large automobile trip shifts, meeting clean electricity goals and reducing material production effects.