Publications

Widespread degradation of marine ecosystems and ecosystem services, coupled with national and global commitments to improve protection of the oceans, has led to a proliferation of efforts to designate new marine protected areas (MPAs) and MPA networks. A range of design features must be considered when designating MPAs, including MPA size and shape, level of protection, and the species and habitats protected, and evidence suggests these design elements can be crucial in determining MPA effectiveness. Over the past several decades, expansive literature has emerged providing recommendations for MPA design, and yet collectively these recommendations can be overwhelming and even contradictory for MPA planners. To address this barrier, we reviewed and synthesized 307 unique MPA design recommendations across 56 peerreviewed and gray literature publications. We created a new set of 24 condensed design guidelines grouped by conservation objectives: ecological spatial connectivity (e.g., genetic, larval, community); habitat representation; species or population persistence; mitigation of and complementarity to human activities; and permanence and adaptability. We then discuss examples of datasets, models, and tools that can be utilized to implement specific guidelines. Our review and novel synthesis can help decision-makers understand and apply MPA design recommendations to achieve desired conservation objectives.

Understanding the economics of food loss-reduction technologies is crucial to promote their adoption. We offer experimental evidence on returns to technology that studies a wide range of food security outcomes and accounts for the quality, quantity, and economic gains from adoption. Using two randomized experiments on improved storage with farmers in India, we find that food loss-reduction technology delivers large gains on multiple aspects of food security. The largest benefits of loss-reduction technology come from reduced quality and economic losses. Using a novel within-farmer experiment, we offer evidence of significant economic incentives for investing in loss-reduction technology in local rural markets. Our cost-benefit analysis shows that farmers recover the full unsubsidized cost of the reusable improved storage technology in one agricultural season.

When fisheries managers cannot see who is fishing or where fishing occurs, their scope for management interventions is limited. This lack of transparency in spatial fishing activity is considered a key enabler of illegal fishing and overfishing and hinders managers and consumers who aim to achieve sustainable fisheries. Increasing transparency in vessel location tracking is gaining momentum as a promising way to improve management of global fisheries. However, the mechanisms through which transparency in vessel activity can improve management have not been carefully studied. This paper provides a conceptual overview of the potential for greater transparency, both in quantity of vessels tracked and availability of data, from vessel tracking to help achieve sustainable fisheries goals. We identify four pathways through which these data can improve fisheries management and the conditions that enable transparency to be an effective governance tool. We qualitatively examine the costs and benefits of alternative models of transparency, including a hypothetical, fully transparent system. We highlight how potential costs and benefits of greater transparency depend on both governance context and management goals, and identify opportunities for future research to address key information gaps.

The winemaking technique of saignée is common for some varietals, and the ensuing flavor profiles have been carefully analyzed by oenologists. However, we argue that saignée is fundamentally about economic tradeoffs between the quantity of primary wine that is ultimately produced, the quality (and thus, price) of that wine, and the amount of rosé wine that is bled off in the process. We develop the first theoretically-grounded economic model of saignée and analyze the model to shed light on the winemaker's optimal choice of saignée, and on the properties of wine and wine markets that should empirically give rise to more, or less, saignée. The model helps to explain several real-world regularities such as the absence of saignée for most Bordeaux wines, the specialization in rosé for many wines in Provence, and the practice of moderate amounts of saignée for varietals such as grenache and pinot noir.

Sharks are susceptible to industrial longline fishing due to their slow life histories and association with targeted tuna stocks. Identifying fished areas with high shark interaction risk is vital to protect threatened species. We harmonize shark catch records from global tuna Regional Fisheries Management Organizations (tRFMOs) from 2012–2020 and use machine learning to identify where sharks are most threatened by longline fishing. We find shark catch risk hotspots in all ocean basins, with notable high-risk areas off Southwest Africa and in the Eastern Tropical Pacific. These patterns are mostly driven by more common species such as blue sharks, though risk areas for less common, Endangered and Critically Endangered species are also identified. Clear spatial patterns of shark fishing risk identified here can be leveraged to develop spatial management strategies for threatened populations. Our results also highlight the need for coordination in data collection and dissemination by tRFMOs for effective shark management.

Landscapes can affect parasite epidemiology in wild and agricultural animals. Honey bees are threatened by loss of floral resources and by parasites, principally the mite Varroa destructor and the viruses it vectors. Existing mite control relies heavily on chemical treatments that can adversely affect bees. Alternative, pesticide-free control methods are needed to mitigate infestation with these ectoparasites. Many flowering plants provide nectar and pollen that confer resistance to parasites. Enrichment of landscapes with antiparasitic floral resources could therefore provide a sustainable means of parasite control in pollinators. Floral rewards of Asteraceae plants can reduce parasitic infection in diverse bee species, including honey and bumble bees. Here, we tested the effects of sunflower (Helianthus annuus) cropland and pollen supplementation on honey bee resistance to macro- and microparasites. Although sunflower had nonsignificant effects on microparasites, We found that increased sunflower pollen availability correlated with reduced Varroa mite infestation in landscapes and pollen-supplemented colonies. At the landscape level, each doubling of sunflower crop area was associated with a 28% reduction in mite infestation. In field trials, late-summer supplementation of colonies with sunflower pollen reduced mite infestation by 2.75-fold relative to artificial pollen. United States sunflower crop acreage has declined by 2% per year since 1980, however, suggesting reduced availability of this floral resource. Although further research is needed to determine whether the observed effects represent direct inhibition of mite fecundity or mite-limiting reductions in honey bee brood-rearing, our findings suggest the potential for sunflower plantings or pollen supplements to counteract a major driver of honey bee losses worldwide.

In 2021, 40% of India’s global greenhouse gas emissions came from electricity generation, mainly powered by coal plants (1). Air pollution from these power plants, composed of predominantly sulfur dioxide and particulate matter, is one of the leading causes of respiratory and heart diseases in India, which result in ∼80,000 premature deaths annually (2). Understanding the impacts of electricity sector policies aimed at mitigating carbon emissions and air pollution is critical for addressing these climate and public health crises. On page 618 of this issue, Sengupta et al. (3) examine how carbon taxes, balancing electricity generation and consumption across larger regions, and sulfur-control regulations affect near-term costs and emissions of India’s electricity sector. They find that these policies can cause inequalities in air pollution exposure across different regions.

This paper studies the response of agricultural production to rural labor loss during the process of urbanization. Using household microdata from India and exogenous variation in migration induced by urban income shocks interacted with distance to cities, we document sharp declines in crop production among migrant-sending households residing near cities. Households with migration opportunities do not substitute agricultural labour with capital, nor do they adopt new agricultural machinery. Instead, they divest from agriculture altogether and cultivate less land. We use a two-sector general equilibrium model with crop and land markets to trace the ensuing spatial reorganization of agriculture. Other non-migrant village residents expand farming (land market channel) and farmers in more remote villages with fewer migration opportunities adopt yield-enhancing technologies and produce more crops (crop market channel). Counterfactual simulations show that over half of the aggregate food production losses driven by urbanization is mitigated by these spillovers. This leads to a spatial reorganization in which food production moves away from urban areas and towards remote areas with low emigration.

Multiple price lists are a convenient tool to elicit willingness to pay (WTP) in surveys and experiments, but choice patterns such as “multiple switching” and “never switching” indicate high error rates. Existing measurement approaches often do not provide accurate standard errors and cannot correct for bias due to framing and order effects. We propose to combine a randomization approach with a random-effects latent utility model to detect bias and account for error. Data from a choice experiment in South Africa shows that significant order effects exist which, if uncorrected, would lead to distorted conclusions about subjects’ preferences. We provide templates to create a multiple price list survey instrument in SurveyCTO and analyze the resulting data using our proposed methods.

Tropical deforestation continues at alarming rates with profound impacts on ecosystems, climate, and livelihoods, prompting renewed commitments to halt its continuation. Although it is well established that agriculture is a dominant driver of deforestation, rates and mechanisms remain disputed and often lack a clear evidence base. We synthesize the best available pantropical evidence to provide clarity on how agriculture drives deforestation. Although most (90 to 99%) deforestation across the tropics 2011 to 2015 was driven by agriculture, only 45 to 65% of deforested land became productive agriculture within a few years. Therefore, ending deforestation likely requires combining measures to create deforestation-free supply chains with landscape governance interventions. We highlight key remaining evidence gaps including deforestation trends, commodity-specific land-use dynamics, and data from tropical dry forests and forests across Africa.

Ecological interactions are not uniform across time and can vary with environmental conditions. Yet, interactions among species are often measured with short-term controlled experiments whose outcomes can depend greatly on the particular environmental conditions under which they are performed. As an alternative, we use empirical dynamic modeling to estimate species interactions across a wide range of environmental conditions directly from existing long-term monitoring data. In our case study from a southern California kelp forest, we test whether interactions between multiple kelp and sea urchin species can be reliably reconstructed from time-series data and whether those interactions vary predictably in strength and direction across observed fluctuations in temperature, disturbance, and low-frequency oceanographic regimes. We show that environmental context greatly alters the strength and direction of species interactions. In particular, the state of the North Pacific Gyre Oscillation seems to drive the competitive balance between kelp species, asserting bottom-up control on kelp ecosystem dynamics. We show the importance of specifically studying variation in interaction strength, rather than mean interaction outcomes, when trying to understand the dynamics of complex ecosystems. The significant context dependency in species interactions found in this study argues for a greater utilization of long-term data and empirical dynamic modeling in studies of the dynamics of other ecosystems.

Climate change is altering the productivity of marine fisheries and challenging the effectiveness of historical fisheries management. Harvest control rules, which describe the process for determining catch limits in fisheries, represent one pathway for promoting climate resilience.  In the United States, flexibility in how regional management councils specify harvest control rules has spawned diverse approaches for reducing catch limits to precautionarily buffer against scientific and management uncertainty, some of which may be more or less resilient to climate change. Here, we synthesize the control rules used to manage all 507 U.S. federally-managed fish stocks and stock complexes. We classified these rules into seven typologies: (1) catch-based; (2) constant catch; (3) constant escapement; (4) constant F; (5) stepped F; (6) ramped F, and (7) both stepped and ramped F. We also recorded whether the control rules included a biomass limit (“cutoff”) value or were environmentally-linked as well as the type and size of the buffers used to protect against scientific and/or management uncertainty. Finally, we review the advantages and disadvantages of each typology for managing fisheries under climate change and provide seven recommendations for updating harvest control rules to improve the resilience of U.S. federally-managed fisheries to climate change.

This paper reviews and extends the recent empirical literature on the impact of climate change on mortality and adaptation in the United States. The analysis produces several new facts. First, the reductions in the impact of extreme heat on mortality risk previously documented up to 2004 have continued up to 2019, consistent with continued investments in health-protecting adaptations to high temperatures. The second part of the paper examines the private and external costs of electricity generation and consumption related to high temperatures, a commonly-used proxy for measuring the consumption of adaptation services. Extreme temperatures increase electricity demand in the residential sector (relative to moderate temperatures), but not in the commercial, industrial, and transportation end-use sectors. The additional electricity demand in response to high temperatures results in significant external costs due to the release of local and global pollutants caused by the combustion of fossil fuels in order to produce electricity. These external costs, documented for the first time in this paper, are one order of magnitude larger than the private cost of adaptation associated with electricity consumption.

Since its release in 2010, the US government’s social cost of carbon (SCC) has played a central role in climate policy both domestically and internationally. However, rapid progress in climate science and economics over the past decade means that the original SCC estimate is no longer based on the frontier of scientific knowledge. Specifically, extensive new research about the climate, the economy, and their relationship has altered our understanding of the magnitudes of the projected physical and economic impacts of climate change, as well as their heterogeneity across space and time. This article, which was written as the Biden presidential administration was actively rebuilding the US SCC, provides concrete recommendations on how to base the SCC on the most recent research advances and thus return it to the scientific frontier.

China’s power system is highly regulated and uses an “equal-share" dispatch approach. However, market mechanisms are being introduced to reduce generation costs and improve system reliability. Here, we quantify the climate and human health impacts brought about by this transition, modeling China’s power system operations under economic dispatch. We find that significant reductions in mortality related to air pollution (11%) and CO₂ emissions (3%) from the power sector can be attained by economic dispatch, relative to the equal-share approach, through more efficient coal-powered generation. Additional health and climate benefits can be achieved by incorporating emission externalities in electricity generation costs. However, the benefits of the transition to economic dispatch will be unevenly distributed across China and may lead to increased health damages in some regions. Our results show the potential of dispatch decision-making in electricity generation to mitigate negative impacts of power plant emissions with existing facilities in China.

The use of vessel tracking systems (VTS) on small-scale fishing vessels can provide data necessary for improved fisheries management. Nevertheless, the adoption of mandated VTS is still limited in small-scale fisheries given the hardship of establishing and enforcing vessel tracking regulations in this fishing sector. However, there is potential for incentivizing voluntary adoption of tracking programs in small-scale vessels. We surveyed small-scale fishers from Indonesia (n = 124) and Mexico (n = 87) to identify which attributes and conditions increase the likelihood of adoption of VTS programs. The survey included a choice experiment to elicit fishers' preferences over attributes of safety, privacy, and data ownership of hypothetical VTS programs along with a bidding game to gauge fishers' willingness to pay. Our results indicated that most fishers in Indonesia and Mexico are willing to pay for VTS programs. VTS programs that included a safety feature were preferred over those that did not. Fishers also indicated that they would prefer VTS programs that provide ownership of the data to fishers or the government instead of the industry or the public. Additionally, we found that individual fisher characteristics are strongly related to willingness to pay and are better predictors of fishers' willingness to pay than the program attributes. Understanding which VTS programs are more likely to be adopted, and by whom, is crucial to uncover the potential of this technology in informing small-scale fisheries management and supporting resource governance.

Clean cooking transitions can have profound public health, environmental and societal gains for 2.6 billion people in the Global South. We use data from the largest household energy survey (n= 7,389) in Ghana to provide novel insights. One, regression analysis with thirteen commonly cited socio-economic and demographic predictors indicates that these factors have remarkably different levels of influence at different stages of the transition process. We propose a stage-based intervention strategy and customer targeting approach that could be a paradigm shift in how clean cooking interventions are rolled out. Two, we identify factors that are associated with exclusive use of LPG using a statistically powered sample of exclusive LPG users (n= 693). We find that everything else being equal, increases in wealth, and residing in an urban location are not associated with a transition from primary to exclusive LPG use.

The magnitude of subsidies provided to the fishing sector by governments worldwide is immense—an estimated $35.4 billion USD per year. The majority of these subsidies may be impeding efforts to sustainably manage fisheries by incentivizing overfishing and overcapacity. Recognizing the threat these subsidies pose, the World Trade Organization has set a goal of reaching an agreement that would end fisheries subsidies that contribute to overcapacity, overfishing, and illegal fishing. However, negotiations have been hampered by uncertainty around the likely effects of reforming these subsidies. Here we present a novel method for translating a bioeconomic model into an interactive online decision support tool that draws upon real-world data on fisheries subsidies and industrial fishing activity so users can directly compare the relative ambition levels of different subsidy reform options.

As the human population and demand for food grow¹, the ocean will be called on to provide increasing amounts of seafood. Although fisheries reforms and advances in offshore aquaculture (hereafter ‘mariculture’) could increase production², the true future of seafood depends on human responses to climate change³. Here we investigated whether coordinated reforms in fisheries and mariculture could increase seafood production per capita under climate change. We find that climate-adaptive fisheries reforms will be necessary but insufficient to maintain global seafood production per capita, even with aggressive reductions in greenhouse-gas emissions. However, the potential for sustainable mariculture to increase seafood per capita is vast and could increase seafood production per capita under all but the most severe emissions scenario. These increases are contingent on fisheries reforms, continued advances in feed technology and the establishment of effective mariculture governance and best practices. Furthermore, dramatically curbing emissions is essential for reducing inequities, increasing reform efficacy and mitigating risks unaccounted for in our analysis. Although climate change will challenge the ocean’s ability to meet growing food demands, the ocean could produce more food than it does currently through swift and ambitious action to reduce emissions, reform capture fisheries and expand sustainable mariculture operations.