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Laxminarayan R.,Center for Disease Dynamics | Laxminarayan R.,Princeton Environmental Institute | Laxminarayan R.,Public Health Foundation of India
Science | Year: 2014

Antibiotic effectiveness is a natural societal resource that is diminished by antibiotic use. As with other such assets, keeping it available requires both conservation and innovation. Conservation encompasses making the best use of current antibiotic effectiveness by reducing demand through vaccination, infection control, diagnostics, public education, incentives for clinicians to prescribe fewer antibiotics, and restrictions on access to newer, last-resort antibiotics. Innovation includes improving the efficacy of current drugs and replenishing effectiveness by developing new drugs. In this paper, I assess the relative benefits and costs of these two approaches to maintaining our ability to treat infections.Copyright © 2014 by the American Association for the Advancement of Science; all rights reserved.


News Article | February 15, 2017
Site: www.eurekalert.org

For decades, among the most enduring questions for ecologists have been: "Why do species live where they do? And what are the factors that keep them there?" A Princeton University-based study featured on the February cover of the journal Ecology could prove significant in answering that question, particularly for animals in the world's temperate mountain areas. The researchers spent two years documenting the distribution of 70 bird species across the Himalayas in India and found that temperature and habitat predominantly determine the elevations where the birds live. Earlier research by other scientists on tropical birds had shown that competition limited the ranges of most species, a conclusion often presumed to be true for temperate zones as well. The researchers found, however, that competition sets the boundaries for a mere 12 percent of Himalayan bird species, while temperature and habitat dictate where 48 and 40 percent of species, respectively, feather their nests. The study is among the first to specifically record temperature across different species' entire elevational ranges; previous studies had used elevation as an unreliable proxy for temperature. The findings provide strong evidence that competition and other factors are not uniformly important across all regions of the world, said co-author David Wilcove, a professor of ecology and evolutionary biology and public affairs and the Princeton Environmental Institute. "The rules of the game are very different in different places," Wilcove said. "It's an important step toward building a comprehensive global perspective. Understanding this could be really important in predicting how life on Earth will change under climate change. If we're not able to understand the rules by which nature is put together, we won't understand how all the things we're doing to the world will affect the wildlife." First author Paul Elsen, who led the study as a Princeton graduate student in ecology and evolutionary biology, explained that the findings indicate that species living in temperate mountain habitats -- particularly in the northern latitudes -- could face even greater repercussions from climate change than previously thought as temperatures rise and habitats change or are disrupted. The researchers selected birds for their ubiquity, variety and ease of observation, but the results could likely apply to many other warm-blooded mountain species, he said. "If species are bound to where they live by temperature, they are going to be much more controlled by temperature moving forward than we may have thought. Where they live in the future will likely directly track local temperature changes resulting from global climate change," said Elsen, now a David H. Smith Conservation Research Fellow at the University of California-Berkeley. "Mountainous regions are very sensitive to climate change because their temperatures are increasing rapidly," Elsen said. "Across the world, we've already seen species shifting their ranges in response to climate change." If scientists and conservationists know the factors that determine why species live where they do, they can more effectively target their efforts and resources to ensure those species' survival, said Wilcove, who was Elsen's doctoral adviser at Princeton. "If the pattern we found for Himalayan birds applies more generally across the temperate zone, we can expect disruptions in the communities of species across those zones in the wake of climate change and land-use change," Wilcove said. "If you know species will have to move -- but we can't predict with confidence exactly where they'll move -- you want to make it as easy as possible for them to get from one place to another and find the resources they need," he said. "That bolsters the case for more parks and reserves spanning more places," Wilcove said. "We have to think about the larger landscape and make sure we have plenty of places for species to go. We also need to find ways to provide corridors of suitable habitat between protected areas so species can move as the climate changes." Because habitats change with elevation, mountains are ideal for studying how species change with temperature and terrain, Elsen said. "If a species is spread out across a vast area, it's extremely difficult to study that species across its entire natural range," he said. "If you work in mountainous areas, however, where each species occupies a particular elevational band, you can step into a species' range in the morning and by the afternoon be at the end of it just by walking upslope. We can study a large number of bird species relatively easily." The study focused on three types of mountain habitat in the Indian Himalayas: mixed broad-leaf and coniferous forests; mixed coniferous forests; and high-altitude forests composed largely of hardy evergreens such as firs. These habitats are similar to those found in other temperate regions, including the United States. Elsen spent four months on foot scouting locations in the Himalayas for his research. He needed relatively undisturbed habitats on continuous elevational gradients ascending the mountainside; at the same time, Elsen had to be able to walk the terrain while burdened with camping and scientific equipment. He spent April-June of 2013 and 2014 trekking across the Indian states of Himachal Pradesh and Uttarakhand collecting data. Elsen, along with co-author and lead field assistant Ramnarayan Kalyanaraman of the Himal Prakriti nature trust in Uttarakhand, recorded the presence and abundance of bird species as well as the habitat and temperature (using monitoring equipment he set up for the duration of the study). Co-author Krishnamurthy Ramesh from the Wildlife Institute of India acted as Elsen's adviser in India and assisted with permits and logistics. The Himalayas exhibit a remarkable diversity of birds, Elsen said -- nearly 10 percent of the world's bird species live there for at least part of the year. Uniquely, the diversity of Himalayan birds increases two-fold as one moves from west to east, he said. Because of that, Elsen and his field assistants were able to isolate and analyze competition as a mechanism for species distribution. The eastern Himalayas have more species and therefore a higher number of potential competitors than the western Himalayas. Thus, if species are limited by competition, birds that occur in both the east and the west should occupy a narrower band of elevation toward the eastern part of their geographic range, Elsen said. But the researchers found that more than three-fourths of species lived side-by-side with their presumed competitors. On the other hand, nearly half of the bird species studied had their elevational ranges determined by temperature or habitat. "Species are actually able to coexist with what we expected to be their dominant competitors," Elsen said. "The numbers of species limited by temperature and habitat, however, are much larger than previous studies from other parts of the world have reported. The significance is that temperature is going to play a much more important role in establishing future distributions than we previously thought." Trevor Price, a professor of biology at the University of Chicago, said that the robust data the researchers provide convincingly portray temperature and habitat as significant determinants of range, not just in the Himalayas but possibly much more broadly. "One of the extremely impressive things about this study is that they managed to document all these bird distributions," said Price, who is familiar with the research but had no role in it. "I think the results are fascinating, and an important contribution. Their results are very general and it would be worth trying to replicate them elsewhere. I really don't think systems are that different around the world," he said. "Theoreticians can use these data to model how we think climate change will affect ranges. As the temperature moves up the mountain, the birds will likely move with it." Yet the findings show that no one factor guides species ranges the world over, Price said. Just as the study found that competition is not universally applicable, the strong influence of temperature in the Himalayas suggests that other factors such as rainfall and parasites might govern species' territories in other parts of the world. "This clearly shows a role for temperature, but it's very difficult to apportion the effects among all the different things that could be going on. I actually believe that temperature is among many factors -- indeed, temperature and precipitation are likely to also affect where prey and other resources are located, thereby indirectly affecting these birds," Price said. "The background data they have now will set the stage for much more rigorous analyses," he said. "Ultimately, we are going to need more detailed studies to ask how the various factors interact. The bottom line is that there has got to be a combination of all these factors at work -- there can't just be one." The paper, "The role of competition, ecotones and temperature in the elevational distribution of Himalayan birds," was published in the February 2017 edition of Ecology. The work was supported by the National Science Foundation (grant no. DGE-1148900), the High Meadows Foundation and the Walbridge Fund.


News Article | November 21, 2016
Site: www.eurekalert.org

Measles, one of the world's most contagious diseases, can spread more quickly in schools than previously thought, according to Princeton University-led research. The researchers report in the journal Proceedings of the National Academy of Sciences that the only sure method of controlling measles among schoolchildren is to maintain very high vaccination rates. The researchers conducted one of the first direct examinations of how measles spreads at the school level by reviewing data from a 1904 measles outbreak in London that affected 18 schools. While schools are known hotspots for infections such as measles, scientists actually have little information about the specific rate at which the measles spreads among children in school, explained senior author Bryan Grenfell, Princeton's Kathryn Briger and Sarah Fenton Professor of Ecology and Evolutionary Biology and Public Affairs. The data came from the Wellcome Library's Collection of digitized historical medical documents maintained by the London-based Wellcome Trust. "This study addresses that gap with historical data," Grenfell said. "We need to be cautious in comparing historical data from the early 1900s to transmission today; however, our study does illustrate the potentially high transmission rates of infection in schools where vaccination is low." First author Alexander Becker, a Princeton graduate student of ecology and evolutionary biology, said, "our direct estimates of measles infection in schools indicate potentially swift transmission rates and a consequent need to maintain vaccination levels." A pathogen's infection rate is indicated by the figure R0 -- pronounced "R nought" -- which indicates how many people catch a disease from the initial carrier in a fully susceptible population, Becker said. In the general population, measles has a notably high transmission rate of R0 = 12-18. In the schools at the center of the 1904 outbreak, the researchers found that at the school level each sick child transmitted measles to an average 27 people with the transmission rate at individual schools falling within a range of 12 to 42. Zooming in to the classroom level, each sick child infected 40 others on average with a transmission-rate range as low as 8 in one school to a whopping 93 in another. Using these historic estimates, the researchers investigated how measles might spread in today's schools. There are presumably notable differences in the living conditions, hygiene and crowding children experienced in London in 1900 versus what children experience in the 21st-century United States, Becker said. Nonetheless, transmission estimates from more recent periods in the pre-vaccination era indicate that measles infection has been quite strongly focused in schools. The researchers developed a mathematical model based on current vaccination estimates in California and found that high vaccination levels were required to prevent transmission. "This work adds more evidence to the benefit of having a fully vaccinated school-age population," Becker said. "Even if a school has high coverage, it should push to go higher because there could be a risk of a significant outbreak." At the same time, Grenfell said, the study emphasizes that the pervasiveness of measles once it infects a school population calls out for a better understanding of how it spreads than scientists currently have. "Probably the most recently studied infection at the school level is influenza," he said. "Our results underline that we also need contemporary studies of measles transmission in schools when it occurs. More generally, our paper emphasizes the importance of digitizing the rich trove of historical data on transmission of infectious disease, as the Wellcome Library did with these data." "These results highlight the importance of sustaining high measles vaccination coverage among school children," said William Moss, a Johns Hopkins University professor of epidemiology, who is familiar with the research but had no role in it. "Because of the high transmissibility of measles virus within schools, outbreaks will occur among the unvaccinated school children should an infectious individual enter the school," he said. The researchers show that at small spatial scales such as schools, highly contagious pathogens can behave with a complexity that becomes obscured in large-scale transmission data from a city or national level, Moss said. A "notable aspect of this research relates to understanding how the more complex dynamics of measles-virus transmission at fine spatial scales such as schools relates to more regular and predictable dynamic patterns at larger spatial scales," Moss said. "The findings are specific to measles but these methods could be applied to other infectious diseases with different and complex dynamics at different spatial scales." In addition, the researchers' application of 1904 data to a current public health scenario illustrates the value of historical information in understanding how diseases spread, Moss said. After all, he said, while society has changed since then, measles has not. "Measles has a characteristic clinical appearance and during outbreaks does not need laboratory confirmation, which didn't exist in 1904," he said. "This shows the value of searching for such data sets and of the stories they can tell that are still of relevance more than 100 years later." Becker and Grenfell worked with Ruthie Birger, a former graduate student in ecology and evolutionary biology now at Columbia University; Aude Teillant, a former research assistant in the Princeton Environmental Institute now at the University of Caen Normandy in France; and Paul Gastanaduy and Gregory Wallace of the Centers for Disease Control and Prevention. The paper, "Estimating enhanced prevaccination measles transmission hotspots in the context of cross-scale dynamics," was published Nov. 21 in the Proceedings of the National Academy of Sciences. The work was supported by the Center for Health and Wellbeing in Princeton's Woodrow Wilson School of Public and International Affairs; the RAPIDD (Research and Policy for Infectious Disease Dynamics) program funded by the U.S. Department of Homeland Security and managed by the National Institutes of Health's Fogarty International Center; and the Bill and Melinda Gates Foundation.


News Article | February 15, 2017
Site: phys.org

The researchers spent two years documenting the distribution of 70 bird species across the Himalayas in India and found that temperature and habitat predominantly determine the elevations where the birds live. Earlier research by other scientists on tropical birds had shown that competition limited the ranges of most species, a conclusion often presumed to be true for temperate zones as well. The researchers found, however, that competition sets the boundaries for a mere 12 percent of Himalayan bird species, while temperature and habitat dictate where 48 and 40 percent of species, respectively, feather their nests. The study is among the first to specifically record temperature across different species' entire elevational ranges; previous studies had used elevation as an unreliable proxy for temperature. The findings provide strong evidence that competition and other factors are not uniformly important across all regions of the world, said co-author David Wilcove, a professor of ecology and evolutionary biology and public affairs and the Princeton Environmental Institute. "The rules of the game are very different in different places," Wilcove said. "It's an important step toward building a comprehensive global perspective. Understanding this could be really important in predicting how life on Earth will change under climate change. If we're not able to understand the rules by which nature is put together, we won't understand how all the things we're doing to the world will affect the wildlife." First author Paul Elsen, who led the study as a Princeton graduate student in ecology and evolutionary biology, explained that the findings indicate that species living in temperate mountain habitats—particularly in the northern latitudes—could face even greater repercussions from climate change than previously thought as temperatures rise and habitats change or are disrupted. The researchers selected birds for their ubiquity, variety and ease of observation, but the results could likely apply to many other warm-blooded mountain species, he said. "If species are bound to where they live by temperature, they are going to be much more controlled by temperature moving forward than we may have thought. Where they live in the future will likely directly track local temperature changes resulting from global climate change," said Elsen, now a David H. Smith Conservation Research Fellow at the University of California-Berkeley. "Mountainous regions are very sensitive to climate change because their temperatures are increasing rapidly," Elsen said. "Across the world, we've already seen species shifting their ranges in response to climate change." If scientists and conservationists know the factors that determine why species live where they do, they can more effectively target their efforts and resources to ensure those species' survival, said Wilcove, who was Elsen's doctoral adviser at Princeton. "If the pattern we found for Himalayan birds applies more generally across the temperate zone, we can expect disruptions in the communities of species across those zones in the wake of climate change and land-use change," Wilcove said. "If you know species will have to move—but we can't predict with confidence exactly where they'll move—you want to make it as easy as possible for them to get from one place to another and find the resources they need," he said. "That bolsters the case for more parks and reserves spanning more places," Wilcove said. "We have to think about the larger landscape and make sure we have plenty of places for species to go. We also need to find ways to provide corridors of suitable habitat between protected areas so species can move as the climate changes." Because habitats change with elevation, mountains are ideal for studying how species change with temperature and terrain, Elsen said. "If a species is spread out across a vast area, it's extremely difficult to study that species across its entire natural range," he said. "If you work in mountainous areas, however, where each species occupies a particular elevational band, you can step into a species' range in the morning and by the afternoon be at the end of it just by walking upslope. We can study a large number of bird species relatively easily." The study focused on three types of mountain habitat in the Indian Himalayas: mixed broad-leaf and coniferous forests; mixed coniferous forests; and high-altitude forests composed largely of hardy evergreens such as firs. These habitats are similar to those found in other temperate regions, including the United States. Elsen spent four months on foot scouting locations in the Himalayas for his research. He needed relatively undisturbed habitats on continuous elevational gradients ascending the mountainside; at the same time, Elsen had to be able to walk the terrain while burdened with camping and scientific equipment. He spent April-June of 2013 and 2014 trekking across the Indian states of Himachal Pradesh and Uttarakhand collecting data. Elsen, along with co-author and lead field assistant Ramnarayan Kalyanaraman of the Himal Prakriti nature trust in Uttarakhand, recorded the presence and abundance of bird species as well as the habitat and temperature (using monitoring equipment he set up for the duration of the study). Co-author Krishnamurthy Ramesh from the Wildlife Institute of India acted as Elsen's adviser in India and assisted with permits and logistics. The Himalayas exhibit a remarkable diversity of birds, Elsen said—nearly 10 percent of the world's bird species live there for at least part of the year. Uniquely, the diversity of Himalayan birds increases two-fold as one moves from west to east, he said. Because of that, Elsen and his field assistants were able to isolate and analyze competition as a mechanism for species distribution. The eastern Himalayas have more species and therefore a higher number of potential competitors than the western Himalayas. Thus, if species are limited by competition, birds that occur in both the east and the west should occupy a narrower band of elevation toward the eastern part of their geographic range, Elsen said. But the researchers found that more than three-fourths of species lived side-by-side with their presumed competitors. On the other hand, nearly half of the bird species studied had their elevational ranges determined by temperature or habitat. "Species are actually able to coexist with what we expected to be their dominant competitors," Elsen said. "The numbers of species limited by temperature and habitat, however, are much larger than previous studies from other parts of the world have reported. The significance is that temperature is going to play a much more important role in establishing future distributions than we previously thought." Trevor Price, a professor of biology at the University of Chicago, said that the robust data the researchers provide convincingly portray temperature and habitat as significant determinants of range, not just in the Himalayas but possibly much more broadly. "One of the extremely impressive things about this study is that they managed to document all these bird distributions," said Price, who is familiar with the research but had no role in it. "I think the results are fascinating, and an important contribution. Their results are very general and it would be worth trying to replicate them elsewhere. I really don't think systems are that different around the world," he said. "Theoreticians can use these data to model how we think climate change will affect ranges. As the temperature moves up the mountain, the birds will likely move with it." Yet the findings show that no one factor guides species ranges the world over, Price said. Just as the study found that competition is not universally applicable, the strong influence of temperature in the Himalayas suggests that other factors such as rainfall and parasites might govern species' territories in other parts of the world. "This clearly shows a role for temperature, but it's very difficult to apportion the effects among all the different things that could be going on. I actually believe that temperature is among many factors—indeed, temperature and precipitation are likely to also affect where prey and other resources are located, thereby indirectly affecting these birds," Price said. "The background data they have now will set the stage for much more rigorous analyses," he said. "Ultimately, we are going to need more detailed studies to ask how the various factors interact. The bottom line is that there has got to be a combination of all these factors at work—there can't just be one." The paper, "The role of competition, ecotones and temperature in the elevational distribution of Himalayan birds," was published in the February 2017 edition of Ecology. Explore further: Reshaping mountains in the human mind to save species facing climate change


News Article | February 27, 2017
Site: www.eurekalert.org

Most strategies to combat climate change concentrate on reducing greenhouse gas emissions by substituting non-carbon energy sources for fossil fuels, but a task force commissioned in June 2016 by former U.S. Secretary of Energy Ernest Moniz proposed a framework in December 2016 for evaluating research and development on two additional strategies: recycling carbon dioxide and removing large amounts of carbon dioxide from the atmosphere. These strategies were developed under a single framework with the goal to produce an overall emissions reduction for the Earth of at least one billion tons of carbon dioxide per year. Task force members said that these approaches would complement carbon-free approaches based on electrification, including wind and solar energy, by fostering low-carbon strategies that retain liquid and gaseous fuels for distributive uses of energy in transport, buildings, and industry. These strategies could also enable overall net carbon removal from the atmosphere, if at some future time the world desires to reduce the global concentration of carbon dioxide. The task force considered only technologies that have the potential to achieve reductions on the scale of one billion metric tons of CO2 per year, which represents about 2.5 percent of annual global emissions (about 40 billion metric tons today). Arun Majumdar, a Stanford University professor who chaired the Task Force of the Secretary of Energy Advisory Board, said that research avenues at such a large scale could potentially include utilizing agricultural crops to store more carbon in the soil, re-using carbon dioxide to form plastics and fuels, and storing carbon dioxide in massive underground reservoirs while producing some fuels. "We are excited to have been able to provide the first steps toward a coherent strategy of research opportunities," Majumdar said. "The range of options that are ripe for research is truly impressive." The task force, made up of participants from eight universities, focused on entire systems. In one example, plants are modified to increase their efficiency in capturing carbon dioxide from the atmosphere during photosynthesis and to develop deeper roots to store the carbon in the soil. By the end of the process, the atmosphere has been scrubbed of the carbon dioxide, and carbon has been transferred from the atmosphere to the soil. Sally Benson, a Stanford professor and a task force member, said a great deal of research is still needed on this process and others included in the report. "Each of the strategies we reviewed has its own research frontier," she said. Because these strategies rely on industry-level solutions such as removing carbon dioxide at the smokestack or changing farming methods to retain carbon in the soil, they require development of new technology and new industrial processes. "The need is urgent, and we must develop and use multiple strategies to combat climate change," said task force member Emily A. Carter, dean of the School of Engineering and Applied Science and founding director of the Andlinger Center for Energy and the Environment at Princeton University. "But pursuing these research avenues will benefit not just climate change. As we have seen for more than a century, investment in science and engineering research pays off in new technologies, new industries, jobs, and societal benefits far beyond the initial expense and in ways we cannot predict." The task force recommendations were delivered in a report to Energy Secretary Ernest J. Moniz on Dec. 13, 2016. John Deutch, an emeritus professor and former provost at the Massachusetts Institute of Technology and the chair of the Secretary of Energy Advisory Board, said in a letter to Moniz that the report "has painted a scientifically interesting agenda for decarbonization that should be of interest to the scientific community writ large." The task force - made up of experts from Duke, Harvard, Georgia Tech, MIT, Princeton, Stanford, University of Illinois and Washington University, as well as a former official from ExxonMobil - cautioned that the development of systems to reduce CO2 emissions at such a scale would be difficult and complex. The members also said some of the techniques could have unexpected outcomes and urged the government to invest in research to evaluate the impacts of the technologies, both intended and unintended, beyond their ability to reduce atmospheric CO2. Taking steps to reduce atmospheric CO2 would require broad cooperation between academic researchers, government and policy leaders, and industry, the report concluded. An appendix to the report analyzes the flow of technology from labs to society and found all of these groups play a critical role in the development of new technology. The task force made five recommendations about research and development: - Improve and expand systems modeling. Members found that because of the complexity of large-scale CO2 reduction, improved models based on a systems approach are needed to evaluate impacts on the atmosphere, ecological systems, and the economy. - Harness the natural biological cycle in which plants absorb and store atmospheric CO2. There is a need to evaluate how to optimize crops to absorb greater amounts of carbon dioxide and store more carbon in the soil for long periods of time, without a major increase in needed resources such as water and fertilizer; how to promote agricultural techniques that extend the time that carbon remains in the soil; and how to use various biological resources, such as giant kelp, as a stock for biofuels. - Explore synthetic transformation of CO2 into useful fuels and products. Carbon dioxide can be converted to valuable chemicals and fuels but it requires energy to do so. A critical part of this system would be inexpensive carbon-free energy to drive this conversion. The task force recommended that the scientific community pursue research to explore better materials and systems that allow for reactions that would make CO2 conversion cheaper and more efficient. - Evaluate the storage of CO2 in geologic formations. Past work on enhanced oil recovery (EOR) focused on minimizing the storage of CO2 to extract hydrocarbons. The task force recommended developing advanced EOR where one would co-optimize CO2 storage and hydrocarbon extraction in such a way that substantially more carbon would be stored than is extracted in fossil fuels. - Study improved methods to separate and capture carbon dioxide from a mixture of gases, a process that is currently too expensive and energy intensive. Both discovery of improved substances to absorb carbon dioxide and development of processes able to separate and store carbon dioxide on a large scale are needed. Improved sorbents would reduce the cost of "direct air capture," which involves absorbing carbon dioxide directly from the air and concentrating it for use or storage. "Our report should help people appreciate the immense effort that will be required to reconfigure our energy system to make it sustainable in the face of climate change, geopolitical stability, and responsible use of land," said Robert Socolow, a professor emeritus of mechanical and aerospace engineering and co-director of the Carbon Mitigation Initiative at the Princeton Environmental Institute. "Our report provides a useful structure for addressing the pluses and minuses of several less familiar approaches."


News Article | November 14, 2016
Site: www.eurekalert.org

Abandoned oil and gas wells are a significant source of greenhouse gases but there are so many scattered across the United States that stopping the leaks presents a huge cost for states. Now, a research team including scientists from Princeton and Stanford universities, has identified specific well attributes that will allow governments to prioritize their repairs. The researchers say it should be possible to eliminate the majority of emissions while minimizing costs by leaving non-emitting abandoned wells alone. "The most effective solution focuses on the highest-emitting wells," said Michael A. Celia, Theodora Shelton Pitney Professor of Environmental Studies and Professor of Civil and Environmental Engineering at Princeton University. "Using our findings, states can apply their resources where it will make the greatest difference." The researchers focused on abandoned wells in western Pennsylvania, because the state has the longest history of oil and gas operations in the United States, but they said their findings may apply to wells across the country. The research shows that the number of wells tracked by regulators most likely is far lower than the true number of abandoned wells, some of which date back to the 1800's. Pennsylvania's Department of Environmental Protection, for example, has records for 31,676 abandoned wells (as of October 2015), while the researchers estimate that the actual number ranges from 470,000 wells to 750,000 wells. In previous work, the Princeton researchers found that many abandoned wells emit methane, a powerful greenhouse gas. They found that in Pennsylvania, methane escaping from abandoned wells made up 4 to 7 percent of state greenhouse gas emissions, which is similar to the new estimate of 5 to 8 percent found in this study. They also found that a small minority of wells tended to emit the large majority of gas. This observation motivated the most recent work, where the group looked for specific attributes that characterize these high-emitters. High emitters represent only about 10 percent of all wells but produce about 90 percent of emissions, according to a 2014 report published by a team including several of the researchers on the current paper and confirmed again in this paper. "We wanted to know what caused the high emissions, and if the data could help prioritize wells for remediation," said Mary Kang, the paper's lead author who worked with Celia and Mauzerall as a doctoral student at Princeton and is now a postdoctoral researcher at Stanford. "In addition to chemical markers, our samples and database analysis showed that physical traits can tell a lot about the wells." In a paper published online on Nov. 14 in the Proceedings of the National Academy of Sciences, the researchers from Princeton, Stanford, Ohio State and Lawrence Berkeley National Laboratory found that two characteristics pointed to high emissions: gas wells that were unplugged, and gas wells in coal regions that were plugged but vented (venting is a safety measure for old wells operated in areas containing coal). Going forward, the researchers said that states with gas drilling should consider alternative safety measures for wells located in coal regions. Neither type of high-emitting wells seems linked to proximity to underground natural gas storage areas or to unconventional oil and gas production, the researchers found. "Our goal in this work was to identify well characteristics that would help identify high emitters and thus provide an opportunity to target them for mitigation and avoid the cost of plugging abandoned wells with low or no emissions" said Denise Mauzerall, professor of civil and environmental engineering and of public and international affairs at Princeton. "Our identification of key characteristics of high emitters will help locate and target for mitigation abandoned wells responsible for the majority of emissions. We hope this approach can be used across the United States and abroad to identify high emitters and target them for remediation." Besides Celia and Mauzerall, the researchers include: Yuheng Chen and Shanna Christian, Department of Geosciences, Princeton University; Alana Miller, Department of Civil and Environmental Engineering, Princeton University; Mary Kang and Robert Jackson, Stanford University; Mark Conrad and Markus Bill, Lawrence Berkeley National Laboratory; and Thomas Darrah, Ohio State University. Support for the work was provided in part by the National Oceanic and Atmospheric Administration, the Princeton Environmental Institute and Vulcan Inc.


News Article | December 15, 2016
Site: www.eurekalert.org

Universal vaccines that protect against multiple strains of influenza virus at once could offer key population-level benefits over conventional seasonal vaccines, according to a new study published in PLOS Computational Biology. Flu-causing viruses are continually evolving. To keep up, scientists must update vaccines regularly so that people can be protected against whichever seasonal strains pose the greatest risk. However, researchers are working to develop universal vaccines that could protect against multiple flu strains without needing to be updated. Research on universal flu vaccines has mostly focused on their potential effects in individual patients. To better understand their effects at the population level, Rahul Subramanian of The University of Chicago and colleagues mathematically modeled the interactions between vaccination, flu transmission, and flu virus evolution. The model revealed that deployment of universal vaccines across large populations could reduce flu transmission more efficiently than conventional vaccines. It could also slow the evolution of new strains of influenza virus and bolster herd immunity, protecting against the emergence of especially dangerous pandemic strains. "New influenza vaccines could, for the first time, maintain their effectiveness in the face of viral evolution," Subramanian says. "In doing so they could transform the way we manage influenza in future." However, conventional vaccines that are well-matched against circulating flu strains are highly effective and are likely to continue to play an important role. Subramanian says that an optimal approach may be to strategically use universal vaccines alongside conventional vaccines to protect at-risk groups while controlling transmission in the whole population. In your coverage please use this URL to provide access to the freely available article in PLOS Computational Biology: http://journals. Citation: Subramanian R, Graham AL, Grenfell BT, Arinaminpathy N (2017) Universal or Specific? A Modeling-Based Comparison of Broad-Spectrum Influenza Vaccines against Conventional, Strain-Matched Vaccines. PLoS Comput Biol 13(1): e1005204. doi:10.1371/journal.pcbi.1005204 Funding: This work was supported by: Health Grand Challenges Program, Center for Health and Wellbeing, Princeton University (RS); and Bob and Cathy Solomon Undergraduate Research Fund, Princeton Environmental Institute, Princeton University (RS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist.


Laxminarayan R.,Princeton Environmental Institute
Oxford Review of Economic Policy | Year: 2016

Emerging threats to global health, including drug-resistant pathogens, emerging pandemics, and outbreaks, represent global trans-boundary commons problems where the actions of individual countries have consequences for other countries. Here, we review what economic analysis can offer in countering these problems through the design of interventions that modify the behaviour of institutions and nations in the direction of greatest global good. © The Authors 2016.


Searchinger T.D.,Princeton Environmental Institute
Environmental Research Letters | Year: 2010

Use of biofuels does not reduce emissions from energy combustion but may offset emissions by increasing plant growth or by reducing plant residue or other non-energy emissions. To do so, biofuel production must generate and use 'additional carbon', which means carbon that plants would not otherwise absorb or that would be emitted to the atmosphere anyway. When biofuels cause no direct land use change, they use crops that would grow regardless of biofuels so they do not directly absorb additional carbon. All potential greenhouse gas reductions from such biofuels, as well as many potential emission increases, result from indirect effects, including reduced crop consumption, price-induced yield gains and land conversion. If lifecycle analyses ignore indirect effects of biofuels, they therefore cannot properly find greenhouse gas reductions. Uncertainties in estimating indirect emission reductions and increases are largely symmetrical. The failure to distinguish 'additional' carbon from carbon already absorbed or withheld from the atmosphere also leads to large overestimates of global bioenergy potential. Reasonable confidence in greenhouse gas reductions requires a precautionary approach to estimating indirect effects that does not rely on any single model. Reductions can be more directly assured, and other adverse indirect effects avoided, by focusing on biofuels from directly additional carbon. © 2010 IOP Publishing Ltd.


Stern R.J.,Princeton Environmental Institute
Energy Policy | Year: 2010

This paper presents the first estimate of United States military cost for Persian Gulf force (CPGfp) derived entirely by a quantitative method. An activity-based cost (ABC) model uses geographic distribution of aircraft carriers as a proxy allocator of Department of Defense (DoD) baseline cost to regional operations. Allocation follows simply from DoD data that since 1990 no less than one aircraft carrier has been continuously on-station in the Persian Gulf; that eight are required to keep one on-station there; that the Navy has had eleven-fifteen carriers since 1990; and that Army and Air Force units are virtually never deployed to combat operations without Navy units. For 1976-2007 CPGfp is estimated to be $6.8×1012 and for 2007 $0.5×1012 (2008$). This substantial military investment is not a remedy for the market failure at the heart of regional security problem, which is oil market power. When CPGfp is added to economic losses attributed to market power in another recent study (Greene, 2010), the severity of this market failure becomes more apparent. © 2010 Elsevier Ltd.

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