Showing 41 - 50 of 80 Items
Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels
Date: 2006-07-25
Creator: Jason Hill, Erik Nelson, David Tilman, Stephen Polasky, Douglas, Tiffany
Access: Open access
- Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feedstocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels. © 2006 by The National Academy of Sciences of the USA.
Projecting global land-use change and its effect on ecosystem service provision and biodiversity with simple models
Date: 2010-12-01
Creator: Erik Nelson, Heather Sander, Peter Hawthorne, Marc Conte, Driss, Ennaanay, Stacie Wolny, Steven Manson, Stephen Polasky
Access: Open access
- Background: As the global human population grows and its consumption patterns change, additional land will be needed for living space and agricultural production. A critical question facing global society is how to meet growing human demands for living space, food, fuel, and other materials while sustaining ecosystem services and biodiversity [1]. Methodology/Principal Findings: We spatially allocate two scenarios of 2000 to 2015 global areal change in urban land and cropland at the grid cell-level and measure the impact of this change on the provision of ecosystem services and biodiversity. The models and techniques used to spatially allocate land-use/land-cover (LULC) change and evaluate its impact on ecosystems are relatively simple and transparent [2]. The difference in the magnitude and pattern of cropland expansion across the two scenarios engenders different tradeoffs among crop production, provision of species habitat, and other important ecosystem services such as biomass carbon storage. For example, in one scenario, 5.2 grams of carbon stored in biomass is released for every additional calorie of crop produced across the globe; under the other scenario this tradeoff rate is 13.7. By comparing scenarios and their impacts we can begin to identify the global pattern of cropland and irrigation development that is significant enough to meet future food needs but has less of an impact on ecosystem service and habitat provision. Conclusions/Significance: Urban area and croplands will expand in the future to meet human needs for living space, livelihoods, and food. In order to jointly provide desired levels of urban land, food production, and ecosystem service and species habitat provision the global society will have to become much more strategic in its allocation of intensively managed land uses. Here we illustrate a method for quickly and transparently evaluating the performance of potential global futures.
Suspense-optimal college football play-offs
Date: 2014-01-01
Creator: Jarrod Olson, Daniel F. Stone
Access: Open access
- U.S. college football’s traditional bowl system, and lack of a postseason play-off tournament, has been controversial for years. The conventional wisdom is that a play-off would be a more fair way to determine the national champion, and more fun for fans to watch. The colleges finally agreed to begin a play-off in the 2014-2015 season, but with just four teams, and speculation continues that more teams will be added soon. A subtle downside to adding play-off teams is that it reduces the significance of regular season games.We use the framework of Ely, Frankel, and Kamenica (in press) to directly estimate the utility fans would get from this significance, that is, utility from suspense, under a range of play-off scenarios. Our results consistently indicate that play-off expansion causes a loss in regular season suspense utility greater than the gain in the postseason, implying the traditional bowl system (two team play-off) is suspense-optimal. We analyze and discuss implications for TV viewership and other contexts.
Accounting for Gender Differences in Cultural Industries: Evidence from Film and the Fine Arts Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Madeleine Rose Dupré
Access: Access restricted to the Bowdoin Community
Economic Costs of Elevated Public Debt Levels During Banking-Crisis Recessions
Date: 2021-01-01
Creator: Gavin T Shilling
Access: Open access
- The Great Recession of 2007 and 2008 exposed the risks of excessive borrowing. We learned the essential economic principle that greater leverage harbors greater risk. Although this global economic contraction was driven primarily by booming private credit expansion, economically inefficient incentives in the public sector, such as short-term reelection concerns, may lead politicians to engage in rash deficit- financed, fiscal spending. The primary purpose of this research is to assess the economic costs of heightened, preexisting government leverage on real economic outcomes during recessionary periods, focusing on both banking and non-banking crisis recessions. In both advanced economies and emerging economies, this study confirms that banking recessions are associated with more severe economic contractions and more persistent output declines than normal recessions. In advanced economies, GDP recovers quickly and strongly with expansionary and supportive fiscal policy during low debt recessions, even with depressed private investment. While GDP recovers slowly and weakly with less expansionary fiscal policy during high debt recessions, even with strong private investment. Thus, the social marginal benefit of public sector investment exceeds the social marginal benefit of private sector investment in advanced economies. In emerging economies, GDP recovers quickly and strongly with strong private investment during high debt recessions, even with weak fiscal spending. While GDP recovers slowly and weakly with depressed private investment during low debt recessions, even with expansionary and supportive fiscal policy. Thus, the social marginal benefit of private sector investment exceeds the social marginal benefit of public sector investment in emerging economies.
Using landscape metrics to characterize towns along an urban-rural gradient
Date: 2021-10-01
Creator: Abigail Kaminski, Dana Marie Bauer, Kathleen P. Bell, Cynthia S. Loftin, Erik J., Nelson
Access: Open access
- Context: Urban-rural gradients are useful tools when examining the influence of human disturbances on ecological, social and coupled systems, yet the most commonly used gradient definitions are based on single broad measures such as housing density or percent forest cover that fail to capture landscape patterns important for conservation. Objectives: We present an approach to defining urban–rural gradients that integrates multiple landscape pattern metrics related to ecosystem processes important for natural resources and wildlife sustainability. Methods: We develop a set of land cover composition and configuration metrics and then use them as inputs to a cluster analysis process that, in addition to grouping towns with similar attributes, identifies exemplar towns for each group. We compare the outcome of the cluster-based urban-rural gradient typology to outcomes for four commonly-used rule-based typologies and discuss implications for resource management and conservation. Results: The resulting cluster-based typology defines five town types (urban, suburban, exurban, rural, and agricultural) and notably identifies a bifurcation along the gradient distinguishing among rural forested and agricultural towns. Landscape patterns (e.g., core and islet forests) influence where individual towns fall along the gradient. Designations of town type differ substantially among the five different typologies, particularly along the middle of the gradient. Conclusions: Understanding where a town occurs along the urban-rural gradient could aid local decision-makers in prioritizing and balancing between development and conservation scenarios. Variations in outcomes among the different urban-rural gradient typologies raise concerns that broad-measure classifications do not adequately account for important landscape patterns. We suggest future urban-rural gradient studies utilize more robust classification approaches.
Managing small natural features: A synthesis of economic issues and emergent opportunities
Date: 2017-07-01
Creator: Dana Marie Bauer, Kathleen P. Bell, Erik J. Nelson, Aram J.K. Calhoun
Access: Open access
- Small natural features (SNFs), landscape elements that influence species persistence and ecological functioning on a much larger scale than one would expect from their size, can also offer a greater rate of return on conservation investment compared to that of larger natural features or more broad-based conservation. However, their size and perceived lack of significance also makes them more vulnerable to threats and destruction. We examine the management of SNFs and conservation of the associated ecosystem services they generate from an economics perspective. Using the economic concept of market failure, we identify three key themes that explain prevailing threats to SNFs and characterize impediments to and opportunities for SNF management: (1) the degree to which benefits derived from the feature spillover, beyond the feature itself (spatially and temporally); (2) the availability and quality of information about the feature and those who most directly influence its management; and (3) the existence and enforcement of property rights and legal standing of the feature. We argue that the efficacy of alternative SNF management approaches is highly case dependent and relies on four key components: (1) the specific ecosystem services of interest; (2) the amount of redundancy of the SNF on the landscape and the level of connectivity required by the SNF in order to provide ecosystem services; (3) the particular market failures that need correcting and their scope and extent; and (4) the magnitude and distribution of management costs.
Estimating the impact of Critical Habitat designation on the values of developed and undeveloped parcels (2nd version, current as of 7/29/2022)
Date: 2022-07-29
Creator: Saleh Mamun, Erik Nelson, Christoph Nolte
Access: Open access
- We use differences-in-differences (DD) estimators to measure the impact that Endangered Species Act (ESA)’s Critical Habitat (CH) rule had on developed and undeveloped parcel prices throughout the US between 2000 and 2019. In a national-level analysis we found that, on average, the price of parcels “treated” with CH were not statistically different than the prices of nearby parcels in listed species range space but not “treated” by CH. CH’s null impact on developed parcel prices is surprising given homeowner’s documented willingness to pay for property surrounded by protected open space. CH’s null impact on undeveloped parcel prices is surprising as previous research had indicated that the impact of CH on undeveloped parcel prices was negative due to the additional regulatory costs and development uncertainty the CH regulation imposes on land developers. When we used relevant subsets of CH areas to measure CH’s impact on parcel prices, we did occasionally find results that were consistent with expectations. We reach two conclusions. First, the impact of the economic impact of the CH rule, holding the impact of other ESA sections constant, cannot be reduced to a simple, consistent narrative. Second, CH’s relatively minor impact on parcel prices suggests that the rule does not have much regulatory “bite.”
The (Far) Backstory of the U.S.-Colombia Free Trade Agreement
Date: 2013-10-10
Creator: Stephen Meardon
Access: Open access
- In two pairs of episodes, first in 1824 and 1846 and then in 1892 and 1935, similar U.S.-Colombia trade agreements or their enabling laws were embraced first by protectionists and then by free traders. The history of the episodes supports the view that although political institutions exist to curb de facto political power, such power may be wielded to undo the institutions’ intended effects. The doctrinal affinities and interests of political actors are more decisive determinants of the free-trade or protectionist orientation of trade agreements than the agreements’ texts or legal superstructures. The long delay from signing to passage of the current U.S.-Colombia Free Trade Agreement is another case in point.
Preparing for and managing change: Climate adaptation for biodiversity and ecosystems
Date: 2013-11-01
Creator: Bruce A. Stein, Amanda Staudt, Molly S. Cross, Natalie S. Dubois, Carolyn, Enquist, Roger Griffis, Lara J. Hansen, Jessica J. Hellmann, Joshua J. Lawler
Access: Open access
- The emerging field of climate-change adaptation has experienced a dramatic increase in attention as the impacts of climate change on biodiversity and ecosystems have become more evident. Preparing for and addressing these changes are now prominent themes in conservation and natural resource policy and practice. Adaptation increasingly is viewed as a way of managing change, rather than just maintaining existing conditions. There is also increasing recognition of the need not only to adjust management strategies in light of climate shifts, but to reassess and, as needed, modify underlying conservation goals. Major advances in the development of climate-adaptation principles, strategies, and planning processes have occurred over the past few years, although implementation of adaptation plans continues to lag. With ecosystems expected to undergo continuing climate-mediated changes for years to come, adaptation can best be thought of as an ongoing process, rather than as a fixed endpoint. © The Ecological Society of America.