Cleanup crew
Human population reduction is not a quick fix for environmental problems
Corey Bradshaw & Barry Brook
Proceedings of the National Academy of Sciences, 18 November 2014, Pages 16610–16615
Abstract:
The inexorable demographic momentum of the global human population is rapidly eroding Earth’s life-support system. There are consequently more frequent calls to address environmental problems by advocating further reductions in human fertility. To examine how quickly this could lead to a smaller human population, we used scenario-based matrix modeling to project the global population to the year 2100. Assuming a continuation of current trends in mortality reduction, even a rapid transition to a worldwide one-child policy leads to a population similar to today’s by 2100. Even a catastrophic mass mortality event of 2 billion deaths over a hypothetical 5-y window in the mid-21st century would still yield around 8.5 billion people by 2100. In the absence of catastrophe or large fertility reductions (to fewer than two children per female worldwide), the greatest threats to ecosystems — as measured by regional projections within the 35 global Biodiversity Hotspots — indicate that Africa and South Asia will experience the greatest human pressures on future ecosystems. Humanity’s large demographic momentum means that there are no easy policy levers to change the size of the human population substantially over coming decades, short of extreme and rapid reductions in female fertility; it will take centuries, and the long-term target remains unclear. However, some reduction could be achieved by midcentury and lead to hundreds of millions fewer people to feed. More immediate results for sustainability would emerge from policies and technologies that reverse rising consumption of natural resources.
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Income and Employment Effects of Shale Gas Extraction Windfalls: Evidence from the Marcellus Region
Dusan Paredes, Timothy Komarek & Scott Loveridge
Energy Economics, January 2015, Pages 112–120
Abstract:
New technologies combining hydraulic fracturing and horizontal drilling in oil and gas extraction are creating a sudden expansion of production. Residents of places where deep underground oil and gas deposits are found want to know about the broader economic, social, and environmental impacts of these activities that generate windfall income for some residents. We first review the literature on windfall spending patterns. Then, using the Marcellus region, the earliest area to be tapped using the new techniques, we estimate county-level employment and income effects. For robustness, we employ two methods. Using a propensity score matching approach we find no effect of fracking on income or employment. A panel-fixed effects regression approach suggests statistically significant employment effects in six out of seven alternative specifications, but significant income effects in only one out of seven specifications. In short, the income spillover effects in the Marcellus region appear to be minimal, meaning there’s little incentive at the county level to incur current or potential future costs that may be associated with this activity. We conclude with some ideas on how localities might employ policies that would allow natural gas extraction to move forward, benefitting landowners, while establishing some financial safeguards for the broader community.
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Victor Lavy, Avraham Ebenstein & Sefi Roth
NBER Working Paper, October 2014
Abstract:
Cognitive performance is critical to productivity in many occupations and potentially linked to pollution exposure. We evaluate this potentially important relationship by estimating the effect of pollution exposure on standardized test scores among Israeli high school high-stakes tests (2000-2002). Since students take multiple exams on multiple days in the same location after each grade, we can adopt a fixed effects strategy estimating models with city, school, and student fixed effects. We focus on fine particulate matter (PM2.5) and carbon monoxide (CO), which are considered to be two of the most dangerous forms of air pollution. We find that while PM2.5 and CO levels are only weakly correlated with each other, both exhibit a robust negative relationship with test scores. We also find that PM2.5, which is thought to be particularly damaging for asthmatics, has a larger negative impact on groups with higher rates of asthma. For CO, which affects neurological functioning, the effect is more homogenous across demographic groups. Furthermore, we find that exposure to either pollutant is associated with a significant decline in the probability of not receiving a Bagrut certificate, which is required for college entrance in Israel. The results suggest that the gain from improving air quality may be underestimated by a narrow focus on health impacts. Insofar as air pollution may lead to reduced cognitive performance, the consequences of pollution may be relevant for a variety of everyday activities that require mental acuity. Moreover, by temporarily lowering the productivity of human capital, high pollution levels lead to allocative inefficiency as students with lower human capital are assigned a higher rank than their more qualified peers. This may lead to inefficient allocation of workers across occupations, and possibly a less productive workforce.
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The Effect of Pollution on Labor Supply: Evidence from a Natural Experiment in Mexico City
Rema Hanna & Paulina Oliva
Journal of Public Economics, forthcoming
Abstract:
Moderate effects of pollution on health may exert important influences on work. We exploit exogenous variation in pollution due to the closure of a large refinery in Mexico City to understand how pollution impacts labor supply. The closure led to a 19.7 percent decline in pollution, as measured by SO2, in the surrounding neighborhoods. The closure led to a 1.3 hour (or 3.5 percent) increase in work hours per week. The effects do not appear to be driven by differential labor demand shocks nor selective migration.
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The Perverse Impact of Calling for Energy Conservation
Scott Holladay, Michael Price & Marianne Wanamaker
Journal of Economic Behavior & Organization, forthcoming
Abstract:
In periods of high energy demand, utilities frequently issue “emergency” appeals for conservation over peak hours to reduce brownout risk. We estimate the impact of such appeals using high-frequency data on actual and forecasted electricity generation, pollutant emission measures, and real-time prices. Our results suggest a perverse impact; while there is no significant reduction in grid stress over superpeak hours, such calls lead to increased off-peak generation, CO2 emissions, and price volatility. We postulate that consumer attempts at load shifting lead to this result.
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Emily Barrett et al.
Hormones and Behavior, November 2014, Pages 787–792
Abstract:
Phthalates, a ubiquitous class of environmental chemicals, may interfere with typical reproductive hormone production both in utero and in adulthood. Although they are best known as anti-androgens, increasingly, evidence suggests that phthalates, particularly di-2-ethylhexyl phthalate (DEHP), may also suppress estrogen production. Given that both androgens and estrogens are essential for sexual function, particularly sexual interest, it is plausible that adult exposure to phthalates alters sexual function. To this end, we used data from 360 women participating in a pregnancy cohort study (the Study for Future Families) to examine whether urinary phthalate metabolite concentrations were associated with two dimensions of self-reported sexual dysfunction in the months prior to conception: lack of sexual interest and vaginal dryness. Women in the highest quartile of urinary concentrations of mono-2-ethyl-5-hydroxyhexyl phthalate, a DEHP metabolite, had 2.58 (95%CI 1.33, 5.00) times the adjusted odds of reporting that they almost always or often lacked interest in sexual activity, and results were similar for mono-2-ethyl-5-oxohexyl phthalate (aOR: 2.56, 95% CI 1.32, 4.95), another DEHP metabolite. Self-reported vaginal dryness was not associated with any phthalate metabolite concentration. This study is novel in its focus on sexual function in relation to environmentally relevant (rather than occupational) exposure to phthalates in adult women and these preliminary findings merit replication in a large, prospective study. Better understanding how adult exposure to phthalates may affect reproductive health, including sexual function, is of public health interest given that virtually all Westerners are exposed to phthalates.
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Matthew Thomas Clement, Christina Ergas & Patrick Trent Greiner
Rural Sociology, forthcoming
Abstract:
This exploratory study examines the effects of rural and urban population change on forest cover at the local level across the southern United States. Using county-level data from the National Land Cover Database and other U.S. government sources, we regressed the total area of forest cover on rural and urban population size in spatial panel models with two-way fixed effects. When we controlled for several other factors, including the number of forestry operations at the county level, regression results indicate that urban change had no effect, but rural population size was positively related to total forest area, and this effect was most pronounced in and around Georgia. Thus, in areas of the southern United States, rural growth was associated with afforestation, not deforestation. We speculate on how this unusual finding contributes to the debate between ecological modernization and urban political economy implicated in previous cross-national research.
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Environmental Health Risks and Housing Values: Evidence from 1,600 Toxic Plant Openings and Closings
Janet Currie et al.
American Economic Review, forthcoming
Abstract:
Regulatory oversight of toxic emissions from industrial plants and understanding about these emissions' impacts are in their infancy. Applying a research design based on the openings and closings of 1,600 industrial plants to rich data on housing markets and infant health, we find that: toxic air emissions affect air quality only within 1 mile of the plant; plant openings lead to 11% declines in housing values within 0.5 mile or a loss of about $4.25 million for these households; and a plant’s operation is associated with a roughly 3% increase in the probability of low birth weight within 1 mile.
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Gray Matters: Fetal Pollution Exposure and Human Capital Formation
Prashant Bharadwaj et al.
NBER Working Paper, November 2014
Abstract:
This paper examines the impact of fetal exposure to air pollution on 4th grade test scores in Santiago, Chile. We rely on comparisons across siblings which address concerns about locational sorting and all other time-invariant family characteristics that can lead to endogenous exposure to poor environmental quality. We also exploit data on air quality alerts to help address concerns related to short-run time-varying avoidance behavior, which has been shown to be important in a number of other contexts. We find a strong negative effect from fetal exposure to carbon monoxide (CO) on math and language skills measured in 4th grade. These effects are economically significant and our back of the envelope calculations suggest that the 50% reduction in CO in Santiago between 1990 and 2005 increased lifetime earnings by approximately 100 million USD per birth cohort.
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Energy Inflation and House Price Corrections
Andreas Breitenfellner, Jesús Crespo Cuaresma & Philipp Mayer
Energy Economics, forthcoming
Abstract:
We analyze empirically the role played by energy inflation as a determinant of downward corrections in house prices. Using a dataset for 18 OECD economies spanning the last four decades, we identify periods of downward house price adjustment and estimate conditional logit models to measure the effect of energy inflation on the probability of these house price corrections after controlling for other relevant macroeconomic variables. Our results give strong evidence that increases in energy price inflation raise the probability of such corrective periods taking place. This phenomenon could be explained by various channels: through the adverse effects of energy prices on economic activity and income reducing the demand for housing; through the particular impact on construction and operation costs and their effects on the supply and demand of housing; through the reaction of monetary policy on inflation withdrawing liquidity and further reducing demand; through improving attractiveness of commodity versus housing investment on asset markets; or through a lagging impact of common factors on both variables, such as economic growth. Our results contribute to the understanding of the pass-through of oil price shocks to financial markets and imply that energy price inflation should serve as a leading indicator for the analysis of macro-financial risks.
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Evelyn Talbott et al.
University of Pittsburgh Working Paper, October 2014
Background: Autism spectrum disorders (ASD) constitute a major public health problem, affecting one in every 68 children. There is little understanding of the cause of ASD despite its serious social impact. Air pollution contains many toxicants known to have adverse effects on the developing fetus.
Methods: We conducted a population-based case control study in six southwestern PA counties estimating the association between ASD and USEPA census tract modeled NATA levels for 30 neurotoxicants. Cases were recruited from local ASD treatment centers. There were two different control groups: 1) Interviewed controls with complete residential histories from pre-pregnancy through age two recruited through mailings using the Pennsylvania Department of Health birth registry (2005-2009). 2) 5,007 non-interviewed controls from a random sample of the birth records using residence at birth. Logistic regression analysis was conducted using quartiles of exposure, adjusting for age of mother, smoking, race, and education.
Results: There were a total of 217 cases. For the first group of 224 controls, median levels of chromium, styrene, cyanide, and polycyclic aromatic hydrocarbons were higher in cases compared to controls (p<.05). Women in the highest quartile of exposure to styrene had an odds ratio of 1.78 (95% CI: 1.035-3.068) of having a child with ASD compared to the lowest quartile, after adjustment for covariates. In the second control group, each increase of interquartile range exposure to cyanide resulted in a 16% higher odds (95%CI; 1.04-3.46) of ASD in the adjusted logistic model. Additionally, women with the highest quartile of exposure to chromium had 1.65 (95%CI; 1.10-2.47) times the odds of having a child with ASD compared to the women in the lowest quartile of chromium exposure.
Conclusions: Chromium, cyanide and styrene exhibited elevated odds ratios using two different control groups. These findings need to be verified with exposure assessment at the individual level.
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Fallout plume of submerged oil from Deepwater Horizon
David Valentine et al.
Proceedings of the National Academy of Sciences, 11 November 2014, Pages 15906–15911
Abstract:
The sinking of the Deepwater Horizon in the Gulf of Mexico led to uncontrolled emission of oil to the ocean, with an official government estimate of ∼5.0 million barrels released. Among the pressing uncertainties surrounding this event is the fate of ∼2 million barrels of submerged oil thought to have been trapped in deep-ocean intrusion layers at depths of ∼1,000–1,300 m. Here we use chemical distributions of hydrocarbons in >3,000 sediment samples from 534 locations to describe a footprint of oil deposited on the deep-ocean floor. Using a recalcitrant biomarker of crude oil, 17α(H),21β(H)-hopane (hopane), we have identified a 3,200-km2 region around the Macondo Well contaminated by ∼1.8 ± 1.0 × 106 g of excess hopane. Based on spatial, chemical, oceanographic, and mass balance considerations, we calculate that this contamination represents 4–31% of the oil sequestered in the deep ocean. The pattern of contamination points to deep-ocean intrusion layers as the source and is most consistent with dual modes of deposition: a “bathtub ring” formed from an oil-rich layer of water impinging laterally upon the continental slope (at a depth of ∼900–1,300 m) and a higher-flux “fallout plume” where suspended oil particles sank to underlying sediment (at a depth of ∼1,300–1,700 m). We also suggest that a significant quantity of oil was deposited on the ocean floor outside this area but so far has evaded detection because of its heterogeneous spatial distribution.
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Regional variation in environmental inequality: Industrial air toxics exposure in U.S. cities
Klara Zwickl, Michael Ash & James Boyce
Ecological Economics, November 2014, Pages 494–509
Abstract:
This paper analyzes how racial and ethnic disparities in exposure to industrial air toxics in U.S. cities vary with neighborhood income, and how these disparities vary regionally across the country. Exposure is estimated at the census block-group level using geographic microdata from the Risk-Screening Environmental Indicators of the U.S. Environmental Protection Agency (EPA). We find that racial and ethnic disparities in pollution exposure are strongest among neighborhoods with median incomes below $25,000, while income-based disparities are stronger among neighborhoods with median incomes above that level. We also find considerable differences in the patterns of disparity across the ten EPA regions. In the two regions with the highest median exposure (the Midwest and South Central regions), for example, African-Americans and Hispanics face significantly higher exposures than whites, whereas in the region with the next highest exposure (the Mid-Atlantic), the reverse is true. We show that the latter result is attributable to intercity variations – minorities tend to live in the less polluted cities in the region – rather than to within-city variations.
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Does Better Information Lead to Better Choices? Evidence from Energy-Efficiency Labels
Lucas Davis & Gilbert Metcalf
NBER Working Paper, November 2014
Abstract:
Information provision is a key element of government energy-efficiency policy, but the information that is provided is often too coarse to allow consumers to make efficient decisions. An important example is the ubiquitous yellow “EnergyGuide” label, which is required by law to be displayed on all major appliances sold in the United States. These labels report energy cost information based on average national usage and energy prices. We conduct an online randomized controlled trial to measure the potential benefits from providing more accurate information. We find that state-specific labels lead to significantly better choices. Consumers invest about the same amount overall in energy-efficiency, but the allocation is much better with more investment in high-usage high-price states and less investment in low-usage low-price states. The implied aggregate cost savings are larger than any reasonable estimate of the cost of implementing state-specific labels.
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The Environmental Effects of Crop Price Increases: Nitrogen Losses in the U.S. Corn Belt
Nathan Hendricks et al.
Journal of Environmental Economics and Management, November 2014, Pages 507–526
Abstract:
High corn prices cause farmers to plant more corn on fields that were planted to corn in the previous year, rather than alternating between corn and soybeans. Cultivating corn after corn requires greater nitrogen fertilizer and some of this nitrogen flows into waterways and causes environmental damage. We estimate the effect of crop prices on nitrogen losses for most fields in Iowa, Illinois, and Indiana using crop data from satellite imagery. Spatial variation in these high-resolution estimates highlights the fact that the environmental effects of agriculture depend not only on what is grown, but also on where and in what sequence it is grown. Our results suggest that the change in corn and soybean prices due to a billion gallons of ethanol production expands the size of the hypoxic zone in the Gulf of Mexico by roughly 30 square miles on average, although there is considerable uncertainty in this estimate.
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Tom Bean et al.
Philosophical Transactions of the Royal Society: Biological Sciences, 19 November 2014
Abstract:
Many wildlife species forage on sewage-contaminated food, for example, at wastewater treatment plants and on fields fertilized with sewage sludge. The resultant exposure to human pharmaceuticals remains poorly studied for terrestrial species. On the basis of predicted exposure levels in the wild, we administered the common antidepressant fluoxetine (FLUOX) or control treatment via prey to wild-caught starlings (Sturnus vulgaris) for 22 weeks over winter. To investigate responses to fluoxetine, birds were moved from their group aviaries into individual cages for 2 days. Boldness, exploration and activity levels showed no treatment effects but controls and FLUOX birds habituated differently to isolation in terms of the concentration of corticosterone (CORT) metabolites in faeces. The controls that excreted higher concentrations of CORT metabolites on day 1 lost more body mass by day 2 of isolation than those which excreted lower levels of CORT metabolites. CORT metabolites and mass loss were unrelated in FLUOX birds. When we investigated the movements of birds in their group aviaries, we found the controls made a higher frequency of visits to food trays than FLUOX birds around the important foraging periods of sunrise and sunset, as is optimal for wintering birds. Although individual variability makes interpreting the sub-lethal endpoints measured challenging, our data suggest that fluoxetine at environmentally relevant concentrations can significantly alter behaviour and physiology.
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An Experimental Test of the Effect of Negative Social Norms on Energy-Efficient Investments
Mike Yeomans & David Herberich
Journal of Economic Behavior & Organization, forthcoming
Abstract:
Energy efficiency is an important economic and environmental concern, and likewise the correction of current wasteful energy practices. We document widespread “tire pressure neglect” - three-quarters of drivers waste gas driving on underinflated tires. Negative descriptive social norms are one potential cause, but have not been tested in high-neglect environments, where those norms are widespread. This confounds the mechanism: are these norms signals of private value to consumers, or do they imply standards for social judgment from others? We conducted a field experiment at gas stations in Chicago - our intervention included treatments with information about tire pressure neglect, promotions in the form of price reductions from $0.50 to free, a descriptive norm of behavior, and “help” in the form of air pump assistance. The treatments are designed to provide the ability to consider four potential underlying drivers: information, monetary cost, social norms and social pressure. Treatments that only included information were ineffective, despite average fuel savings of $10.51, but small promotions had substantial impacts. When the air pump price was free, the social norm discouraged inflation. However, when the research assistant offered help, inflation rates were buoyed by the social norm. These results highlight the importance of incentives over mere information treatments, and offer a new perspective on how information and monetary levers can influence decision-making in the presence of negative social norms.
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Kelly Ramirez et al.
Proceedings of the Royal Society: Biological Sciences, 22 November 2014
Abstract:
Soil biota play key roles in the functioning of terrestrial ecosystems, however, compared to our knowledge of above-ground plant and animal diversity, the biodiversity found in soils remains largely uncharacterized. Here, we present an assessment of soil biodiversity and biogeographic patterns across Central Park in New York City that spanned all three domains of life, demonstrating that even an urban, managed system harbours large amounts of undescribed soil biodiversity. Despite high variability across the Park, below-ground diversity patterns were predictable based on soil characteristics, with prokaryotic and eukaryotic communities exhibiting overlapping biogeographic patterns. Further, Central Park soils harboured nearly as many distinct soil microbial phylotypes and types of soil communities as we found in biomes across the globe (including arctic, tropical and desert soils). This integrated cross-domain investigation highlights that the amount and patterning of novel and uncharacterized diversity at a single urban location matches that observed across natural ecosystems spanning multiple biomes and continents.
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North-south trade in reusable goods: Green design meets illegal shipments of waste
Sophie Bernard
Journal of Environmental Economics and Management, January 2015, Pages 22–35
Abstract:
In a stylized model of international trade, firms in the North indirectly export second-hand products to a representative firm in the South to be reused as intermediate goods, with potential trade gains. The level of reusability of waste products – or green design – is a crucial choice variable in the North. This is because, in the presence of imperfect international monitoring, non-reusable waste can be illegally mixed with reusable waste. I explore the driving forces for illegal waste movement, with a particular focus on local waste regulations such as the EU's Directive on Waste Electrical and Electronic Equipment. Under mild conditions, it is shown that increasingly stringent regulations in the North can induce Northern firms to reduce product reusability. Consequently, the flow of non-reusable waste to the South increases, magnifying the pollution haven effect.
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Edgar Hertwich et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Decarbonization of electricity generation can support climate-change mitigation and presents an opportunity to address pollution resulting from fossil-fuel combustion. Generally, renewable technologies require higher initial investments in infrastructure than fossil-based power systems. To assess the tradeoffs of increased up-front emissions and reduced operational emissions, we present, to our knowledge, the first global, integrated life-cycle assessment (LCA) of long-term, wide-scale implementation of electricity generation from renewable sources (i.e., photovoltaic and solar thermal, wind, and hydropower) and of carbon dioxide capture and storage for fossil power generation. We compare emissions causing particulate matter exposure, freshwater ecotoxicity, freshwater eutrophication, and climate change for the climate-change-mitigation (BLUE Map) and business-as-usual (Baseline) scenarios of the International Energy Agency up to 2050. We use a vintage stock model to conduct an LCA of newly installed capacity year-by-year for each region, thus accounting for changes in the energy mix used to manufacture future power plants. Under the Baseline scenario, emissions of air and water pollutants more than double whereas the low-carbon technologies introduced in the BLUE Map scenario allow a doubling of electricity supply while stabilizing or even reducing pollution. Material requirements per unit generation for low-carbon technologies can be higher than for conventional fossil generation: 11–40 times more copper for photovoltaic systems and 6–14 times more iron for wind power plants. However, only two years of current global copper and one year of iron production will suffice to build a low-carbon energy system capable of supplying the world's electricity needs in 2050.