Assessing Evapotranspiration Estimates from the Global Soil Wetness Project Phase 2 (GSWP-2) Simulations

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/).We assess the simulations of global-scale evapotranspiration from the Global Soil Wetness Project Phase 2 (GSWP-2) within a global water-budget framework. The scatter in the GSWP-2 global evapotranspiration estimates from various land surface models can constrain the global, annual water budget fluxes to within ±2.5%, and by using estimates of global precipitation, the residual ocean evaporation estimate falls within the range of other independently derived bulk estimates. However, the GSWP-2 scatter cannot entirely explain the imbalance of the annual fluxes from a modern-era, observationally-based global water budget assessment, and inconsistencies in the magnitude and timing of seasonal variations between the global water budget terms are found. Inter-model inconsistencies in evapotranspiration are largest for high latitude inter-annual variability as well as for inter-seasonal variations in the tropics, and analyses with field-scale data also highlights model disparity at estimating evapotranspiration in high latitude regions. Analyses of the sensitivity simulations that replace uncertain forcings (i.e. radiation, precipitation, and meteorological variables) indicate that global (land) evapotranspiration is slightly more sensitive to precipitation than net radiation perturbations, and the majority of the GSWP-2 models, at a global scale, fall in a marginally moisture-limited evaporative condition. Finally, the range of global evapotranspiration estimates among the models is larger than any bias caused by uncertainties in the GSWP-2 atmospheric forcing, indicating that model structure plays a more important role toward improving global land evaporation estimates (as opposed to improved atmospheric forcing).NASA Energy and Water-cycle Study (NEWS, grant #NNX06AC30A), under the NEWS Science and Integration Team activities

Meta-Functional Benefit Transfer for Wetland Valuation: Making the Most of Small Samples

This study applies functional Benefit Transfer via Meta-Regression Modeling to derive valuation estimates for wetlands in an actual policy setting of proposed groundwater transfers in Eastern Nevada. We illustrate how Bayesian estimation techniques can be used to overcome small sample problems notoriously present in Meta-functional Benefit Transfer. The highlights of our methodology are (i) The hierarchical modeling of heteroskedasticity, (ii) The ability to incorporate additional information via refined priors, and (ii) The derivation of measures of model performance with the corresponding option of model-averaged Benefit Transfer predictions. Our results indicate that economic losses associated with the disappearance of these wetlands can be substantial and that primary valuation studies are warranted.Bayesian Model Averaging; t-Error Regression Model; Meta-Analysis; Benefit Transfer; Wetland Valuation

The Employment Effects of Downsizing the U.S. Military

This study focuses on the employment effects of military spending versus channeling some significant part of the military budget into alternative purposes.� We begin by introducing the basic input-output modeling technique for considering issues such as these in a systematic way. We then present some simple alternative spending scenarios, namely devoting $1 billion to the military versus the same amount of money spent for five alternatives: tax cuts which produce increased levels of personal consumption; health care; education; mass transit; and construction targeted at home weatherization and infrastructure repair. Our first conclusion in assessing such relative employment impacts is straightforward:$1 billion spent on personal consumption, health care, education, mass transit, and construction for home weatherization and infrastructure will all create more jobs within the U.S. economy than would the same $1 billion spent on the military. We then examine the pay level of jobs created through these alternative spending priorities and assess the overall welfare impacts of the alternative employment outcomes. We then consider what would be the impact on employment of transferring all$138 billion in funding that went to the Iraq war in 2007 into alternative peaceful purposes. As we show, a transfer of funds of this magnitude would enable the U.S. government to provide, for example, health insurance for the 45 million U.S. residents who are now uninsured, and still provide funds for significant investments in education and energy conservation. A transfer of the Iraq budget into these alternative purposes would also expand employment in the U.S. by between 600,000 – 1 million jobs, depending on how exactly the $138 billion were allocated.�

Scenario Models of the World Economy

The purpose of this paper is threefold: First it discusses the case for building an IO-based model of the world economy, second, it discusses the type and the necessary characteristics of such a model and finally it highlights a road map for its construction. In the process it argues for the following set of propositions: a) the necessity of reviving the notion of world models b) the need to take on simultaneously the social-economic and environmental challenges and their interdependence c) the suitability of the IO framework as the basis of the next generation of world models d) the importance of bringing theory to bear on the development of the model and on policy analysis e) the importance of community for the development, support and diffusion of the model and its uses f) asserting the importance of the role of IIOA in building that community g) a focus on interdisciplinarity rather than on the export of economic logic alone to the social and environmental dimensions h) the importance of a scenario-based approach and i) the need to develop and integrate the financial side along with the real side of the economy.Forecast, World Economy;Input-Output Models

Carbon Abatement Costs: Why the Wide Range of Estimates?

Estimates of marginal abatement costs for reducing carbon emissions derived from major economic-energy models vary widely. Controlling for policy regimes, we use meta-analysis to examine the importance of structural modeling choices in explaining differences in estimates. The analysis indicates that particular assumptions about perfectly foresighted consumers and Armington trade elasticities generate lower estimates of marginal abatement costs. Other choices are associated with higher cost estimates, including perfectly mobile capital, inclusion of a backstop technology, and greater disaggregation among regions and sectors. Some features, such as greater technological detail, seem less significant. Understanding the importance of key modeling assumptions, as well as the way the models are used to estimate abatement costs, can help guide the development of consistent modeling practices for policy evaluation.climate models, carbon tax

The U.S. Employment Effects of Military and Domestic Spending Priorities

The war in Iraq is a strategic and moral disaster. But one issue relating to the war that hasn’t been addressed in depth is its impact on the U.S. economy. In the first of a series of research papers that will consider this issue, Robert Pollin and Heidi Garrett-Peltier consider the impact of military spending versus spending on a series of peaceful priorities -- including health care, education, and energy conservation -- on job creation in the U.S. The study finds, for example, that while investing a billion dollars of tax revenue in the military creates 8,500 jobs, investing the same amount in education or mass transit yields more than twice that number of jobs. This study is co-sponsored by the Institute for Policy Studies and Women’s Action for New Directions.

Modeling the impact of an energy price shock on interregional income transfer

Power resources - Prices

On green routing and scheduling problem

The vehicle routing and scheduling problem has been studied with much interest within the last four decades. In this paper, some of the existing literature dealing with routing and scheduling problems with environmental issues is reviewed, and a description is provided of the problems that have been investigated and how they are treated using combinatorial optimization tools