Climate Change, Agriculture, and Food Security in Tanzania

The consequences of climate change for agriculture and food security in developing countries are of serious concern. Due to their reliance on rain-fed agriculture both as a source of income and consumption, many low-income countries are generally considered to be most vulnerable to climate change. Here, we estimate the impact of climate change on food security in Tanzania. Representative climate projections are used in calibrated crop models to predict crop yield changes for 110 districts in Tanzania. These results are in turn imposed on a highly-disaggregated, dynamic economy-wide model of Tanzania. We find that, relative to a no climate change baseline and considering domestic agricultural production as the principal channel of impact, food security in Tanzania appears likely to deteriorate as a consequence of climate change. The analysis points to a high degree of diversity of outcomes (including some favourable outcomes) across climate scenarios, sectors, and regions. The economic modelling indicates that markets have the potential to smooth outcomes on households across regions and income groups, though noteworthy differences in impacts across households persist both by region and by income category.climate change; agriculture; food security; crop model; CGE model; Tanzania

A Method for Calculating Reference Evapotranspiration on Daily Time Scales

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/)Measures of reference evapotranspiration are essential for applications of agricultural management and water resources engineering. Using numerous esoteric variables, one can calculate daily reference evapotranspiration using the Modified Penman-Monteith methods. In 1985, Hargreaves developed a simplified method for estimating reference evapotranspiration. Similarly, Droogers and Allen improved upon Hargreaves’ method in 2002. Both methods provide excellent estimates of average daily rates for a given month, based on monthly climatology. The Hargraeves method also estimates daily rates based on daily data, though the Modified Hargreaves approach developed by Droogers and Allen is largely accepted as a stronger metric. Here efforts are made to improve the functionality of Droogers and Allen’s approach and to adapt it to provide daily estimates of reference evapotranspiration based on daily weather. The Hargreaves and Modified Hargeaves are used to calculate daily reference evapotranspiration based on daily data. The coefficients in these equations are then optimized to reduce the root mean squared difference between each estimate and the baseline value calculated by the Modified Penman-Monteith approach. The adapted method for daily reference evapotranspiration proves promising; estimating rates near a root mean squared difference of 1.07 mm/day. These results are validated with data from 1976-1980; here the root mean squared difference is 1.06 mm/day. Results are evaluated spatially and temporally. Weaknesses are seen in the estimates around clearly-defined summers. Further weaknesses are seen in pole-ward regions. Still, at the 1% significance level, the daily optimization of the Modified Hargreaves equation is found to be the best replica of the Modified Penman-Monteith method, globally. Finally, specific caveats and further avenues of research are noted. Overall, the daily Modified-Hargreaves method is advocated for general use in global studies where daily data and variation is of the utmost concern.This study received support from the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors

Estimating Future Costs for Alaska Public Infrastructure At Risk from Climate Change

Scientists expect Alaska’s climate to get warmer in the coming years— and the changing climate could make it roughly 10% to 20% more expensive to build and maintain public infrastructure in Alaska between now and 2030 and 10% more expensive between now and 2080. These are the first estimates of how much climate change might add to future costs for public infrastructure in Alaska, and they are preliminary. “Public infrastructure” means all the federal, state, and local infrastructure that keeps Alaska functioning: roads, bridges, airports, harbors, schools, military bases, post offices, fire stations, sanitation systems, the power grid, and more. Privately owned infrastructure will also be affected by climate change, but this analysis looks only at public infrastructure.University of Alaska Foundation; National Commission on Energy Policy, Washington D.C.; Alaska Conservation Foundation, Anchorage; Alaska Rural Alaska Community Action Program, Anchorage, Alask

Valuing Climate Impacts in Integrated Assessment Models: The MIT IGSM

http://globalchange.mit.edu/research/publications/reports/allWe discuss a strategy for investigating the impacts of climate change on Earth’s physical, biological and human resources and links to their socio-economic consequences. The features of the integrated global system framework that allows a comprehensive evaluation of climate change impacts are described with particular examples of effects on agriculture and human health. We argue that progress requires a careful understanding of the chain of physical changes—global and regional temperature, precipitation, ocean acidification and polar ice melting. We relate those changes to other physical and biological variables that help people understand risks to factors relevant to their daily lives—crop yield, food prices, premature death, flooding or drought events, land use change. Finally, we investigate how societies may adapt, or not, to these changes and how the combination of measures to adapt or to live with losses will affect the economy. Valuation and assessment of market impacts can play an important role, but we must recognize the limits of efforts to value impacts where deep uncertainty does not allow a description of the causal chain of effects that can be described, much less assigned a likelihood. A mixed approach of valuing impacts, evaluating physical and biological effects, and working to better describe uncertainties in the earth system can contribute to the social dialogue needed to achieve consensus—where it is needed—on the level and type of mitigation and adaptation actions that are required.The MIT Integrated Global System Model (IGSM) and its economic component used in the analysis, the MIT Emissions Prediction and Policy Analysis (EPPA) model, is supported by a consortium of government, industry, and foundation sponsors of the MIT Joint Program on the Science and Policy of Global Change. (For a complete list of sponsors, see: http://globalchange.mit.edu)

The costs of adaptation to climate change for water infrastructure in OECD countries

There is concern that climate change may greatly increase the costs of providing water infrastructure in rich countries, but the estimates available cannot be compared across countries. This paper develops and applies a top-down approach to estimate the costs of adapting to climate change on a consistent basis for different climate scenarios. The analysis separates (a) the costs of maintaining service standards for a baseline projection of demand, and (b) the costs of changes in water use and infrastructure as a consequence of changes in climate patterns. The engineering estimates focus on the direct capital and operating costs of adaptation without relying upon economic incentives to affect patterns of water use. On this assumption, the costs of adaptation are 1-2% of baseline costs for all OECD countries with the main element being the extra cost of water resources to meet higher level of municipal water demand. There are large differences in the cost of adaptation across countries and regions. Adopting an economic approach under which water levies are used to cap total water abstractions leads to a large reduction in the burden of adaptation and generates savings of $6-12 billion per year under different climate scenarios.Climate change Adaptation Infrastructure Water supply Wastewater

The changing nature of human-forced hydroclimatic risks across Africa

We present results from large ensembles of projected 21st century changes in seasonal precipitation and near-surface air temperature over Africa and selected sub-continental regions. These ensembles are a result of combining Monte Carlo projections from a human-Earth system model of intermediate complexity with pattern-scaled responses from climate models of the Coupled Model Intercomparison Project Phase 6. These future ensemble scenarios consider a range of global actions to abate emissions through the 21st century. We evaluate distributions of surface-air temperature and precipitation change. In all regions, we find that without any emissions or climate targets in place, there is a greater than 50% likelihood that mid-century temperatures will increase threefold over the current climate’s two-standard deviation range of variability. However, scenarios that consider more aggressive climate targets all but eliminate the risk of these salient temperature increases. A preponderance of risk toward decreased precipitation exists for much of the southern Africa region considered, and this is also compounded by enhanced warming (relative to the global trajectory). Over eastern and western Africa, the preponderance of risk in increased precipitation change is seen. Strong climate targets abate evolving regional hydroclimatic risks. Under a target to limit global climate warming to 1.5˚C by 2100, the risk of precipitation changes within Africa toward the end of this century (2065-2074) is commensurate to the risk during the 2030s without any global climate target. Thus, these regional hydroclimate risks over much Africa could be delayed by 30 years, and in doing so, provide invaluable lead-time for national efforts to prepare, fortify, and/or adapt

The changing nature of hydroclimatic risks across South Africa

Abstract We present results from large ensembles of projected twenty-first century changes in seasonal precipitation and near-surface air temperature for the nation of South Africa. These ensembles are a result of combining Monte Carlo projections from a human-Earth system model of intermediate complexity with pattern-scaled responses from climate models of the Coupled Model Intercomparison Project Phase 5 (CMIP5). These future ensemble scenarios consider a range of global actions to abate emissions through the twenty-first century. We evaluate distributions of surface-air temperature and precipitation change over three sub-national regions: western, central, and eastern South Africa. In all regions, we find that without any emissions or climate targets in place, there is a greater than 50% likelihood that mid-century temperatures will increase threefold over the current climate’s two-standard deviation range of variability. However, scenarios that consider more aggressive climate targets all but eliminate the risk of these salient temperature increases. A preponderance of risk toward decreased precipitation (3 to 4 times higher than increased) exists for western and central South Africa. Strong climate targets abate evolving regional hydroclimatic risks. Under a target to limit global climate warming to 1.5 °C by 2100, the risk of precipitation changes within South Africa toward the end of this century (2065–2074) is commensurate to the risk during the 2030s without any global climate target. Thus, these regional hydroclimate risks over South Africa could be delayed by 30 years and, in doing so, provide invaluable lead-time for national efforts to prepare, fortify, and/or adapt

Understanding Alaska Research Summary No. 8

Scientists expect Alaska’s climate to get warmer in the coming years— and the changing climate could make it roughly 10% to 20% more expensive to build and maintain public infrastructure in Alaska between now and 2030 and 10% more expensive between now and 2080. These are the first estimates of how much climate change might add to future costs for public infrastructure in Alaska, and they are preliminary.Understanding Alaska (UA) is a special series of ISER research studies examining Alaska economic development issues. The studies are funded by the University of Alaska Foundation. The full report was sponsored by University of Alaska Foundation; National Commission on Energy Policy (Washington DC); Alaska Conservation Foundation (Anchorage AK); Rural Alaska Community Action Program (Anchorage AK