Tingju Zhu

Food security, farming, and climate change to 2050: Scenarios, results, policy options

As the global population grows and incomes in poor countries rise, so too, will the demand for food, placing additional pressure on sustainable food production. Climate change adds a further challenge, as changes in temperature and precipitation threaten agricultural productivity and the capacity to feed the worlds population. This study assesses how serious the danger to food security might be and suggests some steps policymakers can take to remedy the situation.

Economic consequences of optimized water management for a prolonged, severe drought in California

If abrupt climate change has occurred in the past and may be more likely under human forcing, it is relevant to look at the adaptability of current infrastructure systems to severe conditions of the recent past. Geologic evidence suggests two extreme droughts in California during the last few thousand years, each 120-200 years long, with mean annual streamflows 40%-60% of the historical mean. This study synthesized a 72 year drought with half of mean historical inflows using random sampling of historical dry years. One synthetic hydrological record is used, and sensitivity to different interpretations of the paleorecord is not evaluated. Economic effects and potential adaptation of Californias water supply system in 2020 to this drought is explored using a hydroeconomic optimization model. The model considers how California could respond to such an extreme drought using water trading and provides best-case estimates of economic costs and effects on water operations and demands. Results illustrate the ability of extensive, intertied, and flexible water systems with heterogeneous water demands to respond to severe stress. The study follows a different approach to climate change impact studies, focusing on past climate changes from the paleorecord rather than downscaled general circulation model results to provide plausible hydrologic scenarios. Adaptations suggested for the sustained drought are similar for dry forms of climate warming in California and are expensive but not catastrophic for the overall economy but would impose severe burdens on the agricultural sector and environmental water uses.

Yellow River basin: living with scarcity

The Yellow River basin is a key food production centre of global importance facing rapidly growing water scarcity. Water availability for agriculture in the basin is threatened by rapid growth in the demand for industrial and urban water, the need to flush sediment from the rivers lower reaches, environmental demands and growing water pollution. Climate change is already evident in the basin with long-term declines in river runoff, higher temperatures, and increasing frequency and intensity of drought. The Chinese government has exhausted most options for improving water supply. The challenge will be to switch to improved water demand management, which is hampered by existing governance structures, and lack of integrated agriculture and water resource policies.

Droughts in Pakistan: a spatiotemporal variability analysis using the Standardized Precipitation Index

We investigated the spatiotemporal variability of drought incidence in Pakistan during 1960–2007 by calculating Standardized Precipitation Index fields for 3-, 6- and 12-month scales using gridded precipitation data. Principal component analysis revealed that droughts are wide-spread and often occur simultaneously over large areas. Furthermore, spectral analysis identified a 16-year drought recurrence period. Three such drought-intensive periods were identified: the late 1960s to early 1970s; the middle 1980s; and the late 1990s to early 2000s. Hence, drought patterns need to be integrated into long-term water planning as well as emergency preparedness.

Current Climate Variability and Future Climate Change: Estimated Growth and Poverty Impacts for Zambia

Economy-wide and hydrological-crop models are combined to estimate and compare the economic impacts of current climate variability and future anthropogenic climate change in Zambia. Accounting for uncertainty, simulation results indicate that, on average, current variability reduces gross domestic product by four percent over a ten-year period and pulls over two percent of the population below the poverty line. Socio-economic impacts are much larger during major drought years, thus underscoring the importance of extreme weather events in determining climate damages. Three climate change scenarios are simulated based on projections for 2025. Results indicate that, in the worst case scenario, damages caused by climate change are half the size of those from current variability. We conclude that current climate variability, rather than climate change, will remain the more binding constraint on economic development in Zambia, at least over the next few decades.

Climate Warming & California's Water Future

Few states depend more on climatic stability than California. While the California water system is designed fairly well to accommodate repeats of historical droughts in the near future, there is concern that California might not be able to easily accommodate major droughts in the more distant future, especially with the hydrologic consequences of significant climate warming. This study developed comprehensive surface and ground water hydrologies for 12 climate warming scenarios for Californias inter-tied water system, as well as economic water demand estimates for urban and agricultural uses for estimates 2100 population levels. The most severe of these 12 climatic warming hydrologies was then employed with these 2100 economic water demands as inputs into an integrated economic-engineering optimization model of Californias inter-tied water system (CALVIN). The results indicate the effects of population growth and climatic change on the performance of Californias water system, as well as promising water management strategies to respond to these changes in supply and demand conditions over the coming century.

Water Resources Impacts

Models are used to estimate potential physical and biological impacts, efficient adaptations, and residual damages from climate change. The contributors cover a broad array of climate change impacts on affected market sectors (including water supply, agriculture, coastal resources, timber, and energy demand) as well as ecosystems and biodiversity. An integrated hydrologic-agriculture model is developed to explore how the region would adapt to changes in water flows. Interactions between climate impacts and population and economic growth, urbanization, and technological change are also explored. For example, the study examines how both climate change and projected land development affect the region’s terrestrial ecosystems and biodiversity.

Hydroeconomic optimization of integrated water management and transfers under stochastic surface water supply

Efficient reallocation and conjunctive operation of existing water supplies is gaining importance as demands grow, competitions among users intensify, and new supplies become more costly. This paper analyzes the roles and benefits of conjunctive use of surface water and groundwater and market-based water transfers in an integrated regional water system where agricultural and urban water users coordinate supply and demand management based on supply reliability and economic values of water. Agricultural users optimize land and water use for annual and perennial crops to maximize farm income, while urban users choose short-term and long-term water conservation actions to maintain reliability and minimize costs. The temporal order of these decisions is represented in a two-stage optimization that maximizes the net expected benefits of crop production, urban conservation and water management including conjunctive use and water transfers. Long-term decisions are in the first stage and short-term decisions are in a second stage based on probabilities of water availability events. Analytical and numerical analyses are made. Results show that conjunctive use and water transfers can substantially stabilize farmers income and reduce system costs by reducing expensive urban water conservation or construction. Water transfers can equalize marginal values of water across users, while conjunctive use minimizes water marginal value differences in time. Model results are useful for exploring the integration of different water demands and supplies through water transfers, conjunctive use, and conservation, providing valuable insights for improving system management.

Climate change impacts and adaptation options for water and food in Pakistan: scenario analysis using an integrated global water and food projections model

Climate change is expected to considerably affect the water resources in the Indus River basin in Pakistan and thus agricultural production in the country. This article reports an analysis of the impacts of various climate scenarios on both water resources and food production out to 2050. While changes in water availability range from –12% to +24%, depending on the scenario, crop yield and production impacts are negative across all scenarios, and net food imports increase. We suggest a combination of accelerated investment in agricultural research and increased water-use efficiency in agriculture to reduce the adverse impacts of climate change on water and food.

Global linkages among energy, food and water: an economic assessment

The resolution adopted by the General Assembly of the United Nations on 25 September 2015 is symptomatic of the water-energy-food (WEF) nexus. It postulates goals and related targets for 2030 that include (1) End hunger, achieve food security and improved nutrition, and promote sustainable agriculture (SDG2); (2) Ensure availability and sustainable management of water and sanitation for all (SDG6); and (3) Ensure access to affordable, reliable, sustainable, and modern energy for all (SDG7). There will be tradeoffs between achieving these goals particularly in the wake of changing consumption patterns and rising demands from a growing population expected to reach more than nine billion by 2050. This paper uses global economic analysis tools to assess the impacts of long-term changes in fossil fuel prices, for example, as a result of a carbon tax under the UNFCCC or in response to new, large findings of fossil energy sources, on water and food outcomes. We find that a fossil fuel tax would not adversely affect food security and could be a boon to global food security if it reduces adverse climate change impacts.