Publications

The spatial distribution of many public lands in the western U.S. is an artifact of 19th century land-disposal policies. While this legacy is sometimes an impediment to conservation, it may also provide novel opportunities to spatially reorganize public conservation lands within realistic budget constraints. Here we seek to understand the conservation potential of strategically rearranging inaccessible (“stranded”) public land in Montana, US. We use conservation reserve network design and consider coarse- and fine-filter conservation features—land cover types and predicted habitat for 12 umbrella species, respectively—and incorporate habitat connectivity corridors into one reserve design scenario. All conservation reserve network designs are constrained by a budget equal to the current value of stranded public land parcels and seek to meet or exceed the extent of conservation currently provided by stranded parcels with respect to land cover type and predicted species habitat. We find that each conservation reserve simulation expands the total protected area in Montana within the realistic budget constraint. Two maximum coverage scenarios, which exhaust the budget, result in reserve designs that substantially exceed coarse- and fine-filter conservation targets. All reserve designs provide landscape connectivity benefits. Our results illustrate notable and practical opportunities to develop conservation reserve networks in the western US that account for landscape connectivity and that benefit both private landowners and biodiversity conservation efforts through land trades and acquisitions.

Using 40 countries’ subnational data, we estimate age-specific mortality-temperature relationships and extrapolate them to countries without data today and into a future with climate change. We uncover a U-shaped relationship where extre6me cold and hot temperatures increase mortality rates, especially for the elderly. Critically, this relationship is flattened by higher incomes and adaptation to local climate. Using a revealed-preference approach to recover unobserved adaptation costs, we estimate that the mean global increase in mortality risk due to climate change, accounting for adaptation benefits and costs, is valued at roughly 3.2% of global GDP in 2100 under a high-emissions scenario. Notably, today’s cold locations are projected to benefit, while today’s poor and hot locations have large projected damages. Finally, our central estimates indicate that the release of an additional ton of CO₂ today will cause mortality-related damages of $36.6 under a high-emissions scenario, with an interquartile range accounting for both econometric and climate uncertainty of [−$7.8, $73.0]. These empirically grounded estimates exceed the previous literature’s estimates by an order of magnitude.

Costs of fighting wildfires have increased substantially over the past several decades. Yet surprisingly little is known about the effectiveness of wildfire suppression or how wildfire incident managers prioritize resources threatened within a wildfire incident. We investigate the determinants of wildfire suppression effort using a novel empirical strategy comparing over 1,400 historical fire perimeters to the spatial distribution of assets at risk. We find that fires are more likely to stop spreading as they approach homes, particularly when homes are of greater value. This effect persists after controlling for physical factors (fuels, landscape, and weather) using a state-of-the-art wildfire simulation tool. As well, the probability that spread will be halted is affected by characteristics of homes 1–2 kilometers beyond a fire’s edge. Overall, we find that suppression efforts can substantively affect wildfire outcomes but that some groups may benefit more from wildfire management than others.

Credit markets and property rights are fundamental for modern economies, but they also have implications for the commons. Using a dynamic model of competitive resource extraction, we show that improving property right security unambiguously increases conservation incentives, but the effect of credit markets on resource extraction effort hinges on the security of property rights. We test these predictions using data on global fisheries, credit markets, and the largest-ever marine property rights assignment. We find that property right security reduces resource extraction, while credit market development increases resource extraction under insecure property rights but reduces resource extraction under secure property rights.

Fuel break effectiveness in wildland-urban interface (WUI) is not well understood during downslope wind-driven fires even though various fuel treatments are conducted across the western United States. The aim of this paper is to examine the efficacy of WUI fuel breaks under the influence of strong winds and dry fuels, using the 2018 Camp Fire as a case study. The operational fire growth model Prometheus was used to show: (1) downstream impacts of 200 m and 400 m wide WUI fuel breaks on fire behavior and evacuation time gain; (2) how the downstream fire behavior was affected by the width and fuel conditions of the WUI fuel breaks; and (3) the impacts of background wind speeds on the efficacy of WUI fuel breaks. Our results indicate that WUI fuel breaks may slow wildfire spread rates by dispersing the primary advancing fire front into multiple fronts of lower intensity on the downstream edge of the fuel break. However, fuel break width mattered. We found that the lateral fire spread and burned area were reduced downstream of the 400 m wide WUI fuel break more effectively than the 200 m fuel break. Further sensitivity tests showed that wind speed at the time of ignition influenced fire behavior and efficacy of management interventions.

Natural resources such as carbon, water, and fish are increasingly managed with markets that require an initial allocation of property rights. In practice these rights are typically grandfathered based on historical use, but rights could be allocated any number of ways. Taking the perspective of a currently unregulated firm, we ask how the anticipation of a future market affects extraction incentives, environmental quality, and welfare prior to the implementation of the market. We show that this anticipation has first-order welfare implications, seemingly contradicting the widely held belief that the allocation of rights has no aggregate welfare consequences. The most egregious case involves anticipation of a traditional grandfathering rule, which induces a race for allocation before the market goes into effect, causing over-extraction or over-emissions, even relative to the completely unregulated baseline. We derive an alternative allocation rule called "Reverse-Grandfathering" that still provides a free allocation of rights but reverses the marginal incentive to emit or extract. We show that this new approach, which relies on incentives due to anticipation, can replicate welfare-maximizing firm behavior, even in the complete absence of regulation. To illustrate the potential magnitude of anticipation effects, we develop and parameterize a structural model of a hypothetical market among nearly 5,000 large fishing firms on the high seas. Relative to traditional grandfathering and auctioning of rights, ReverseGrandfathering substantially increases natural resource stocks and welfare.

The adoption of sustainable alternative foods could potentially reduce the environmental burden of human food production if it can reduce demand for products with higher environmental impact. However, there is little empirical evidence for how frequent food consumption declines are when alternative foods are introduced, limiting our knowledge of the potential for such introductions to drive food system transformations. Using 53 years of food supply data for 99 crop, livestock, and seafood commodities in 159 countries, we use regression analyses on 12 883 time series—each representing a single country-commodity pair—to detect sustained declines in apparent national food consumption, as well as corresponding consumption increases of other food commodities. First, we show that sustained declines in the consumption of any food item are rare, occurring in 9.6% of time series. Where declines are present, they most frequently occur in traditional plant-based staples, e.g. starchy roots, and are larger compared to animal-source foods, particularly in low- and middle-income countries where much of the future increase in food demand is expected to occur. Second, although declines were rare, we found national production rather than trade was identified as the most common proximate driver of declines in consumption, suggesting that shifts in diets have the potential to translate into reduced environmental impacts from food production. Third, we found consumption increases were nearly twice as common as declines, but only 8% of declines (from within 4% of total time series) occurred parallel to incline events within the same food group, suggesting limited interchangeability. An examination of case studies suggests that alternative foods can facilitate food system transitions, but strong relative disadvantages for existing foods across aspects of technology, markets, policy and culture need to exist in parallel to support for alternative foods across the same factors. Where existing foods are already produced in highly efficient systems, a lack of systematic disadvantage may provide a barrier to alternative foods driving change.

Labor issues and human rights violations have become the subject of rising concern in fisheries and seafood production. This paper reviews recent research on labor issues in the fishing industry, especially by environmental researchers and nongovernmental organizations (NGOs) which are emerging as key players in research and policy arenas. Recent research has focused largely on severe violations such as forced labor, particularly in ‘hotspot’ geographies, often relying on indicators and risk-based approaches given the paucity of data and challenges of monitoring working conditions. This paper proposes that decent work – a concept associated with the institutional history of the International Labor Organization (ILO) but with broad implications – can contribute to overcoming gaps in the research landscape, and assessing and improving a range of labor issues in fisheries. The paper elaborates some key considerations for studying and promoting decent work in the seafood industry. Assessing and achieving decent work in the world’s fisheries requires (1) a holistic human rights approach to decent work, in which labor concerns are understood in the context of interrelated and interdependent sets of human rights, (2) consideration of the complex political-economic regimes and histories in which seafood production is embedded, and perhaps most importantly, (3) that workers play a central role and have a voice in defining and achieving decent work. The paper concludes with future directions for research and a discussion of promising and emerging policy pathways for promoting decent work in fisheries and seafood production.

Coral reef fisheries are vital to the livelihoods of millions of people worldwide but are challenging to manage due to the high diversity of fish species that are harvested and the multiple types of fishing gear that are used. Fish traps are a commonly used gear in reef fisheries in the Caribbean and other regions, but they have poor selectivity and frequently capture juvenile fish, impacting the sustainability of the fishery. One option for managing trap fisheries is the addition of escape gaps, which allow small fish to escape. We compared catches of traps with and without two 2.5 cm (1 inch) escape gaps on the Caribbean island of Montserrat. No significant differences were found in the mean fish length, total fish biomass, number of fish, fish species richness, and Shannon diversity index between hauls of the two trap designs, though traps with escape gaps did catch larger proportions of wider-bodied fish and smaller proportions of narrow-bodied fish. Furthermore, traps with gaps caught a smaller proportion of small-sized fish and fewer immature fish (though differences were not statistically significant). Linear mixed effect models predict that soak time (the length of time between trap hauls) increases the mean catch length, total catch biomass and total number of species in the catch. The relatively modest evidence for the effect of the gaps on catch may be explained by the long soak times used, which could have allowed most smaller-sized fish to escape or be consumed by larger individuals before hauling in both traps with and without escape gaps. Despite the small differences detected in this study, escape gaps may still offer one of the best options for improving sustainability of catches from fish traps, but larger escape gaps should be tested with varying soak times to determine optimum escape gap size.

Marine protected areas (MPAs) are an important tool for conservation but can be victims of their own success—higher fish biomass within MPAs create incentives to poach. This insight underpins the finding that fishing persists in most MPAs worldwide, and it raises questions about MPA monitoring and enforcement. We propose a novel institution to enhance MPA design—a ‘Conservation Finance Area (CFA)’—that utilizes leased fishing zones inside of MPAs, fed by spillover, to finance monitoring and enforcement and achieve greater conservation success. Using a bioeconomic model we show that CFAs can fully finance enforcement, deter illegal fishing, and ultimately maximize fish biomass. Moreover, we show that unless a large, exogenous, and perpetual enforcement budget is available, implementing a CFA in a no-take MPA would always result in higher biomass than without. We also explore real-world enabling conditions, providing a plausible funding pathway to improve outcomes for existing and future MPAs.

Small-scale reef fisheries are important commercial and subsistence activities that support the livelihoods of millions of people in tropical regions. Tropical marine fisheries typically target a diversity of species caught with a matching diversity of fishing gears and practices. Here, we explored how multiple fishing gears select for distinct functional traits of fish assemblages inside a large multiple use marine environmental protected area off northeastern Brazil. In 1833 landing interviews with local fishers, we identified 101 species, which were categorized according to six traits: body size, schooling behavior, mobility, position in the water column, diet and period of activity. Our research is the first to explore the broad patterns of gear selectivity with regards to fish functional traits for different habitat types. While gears used in reef habitats were highly selective of sedentary and benthic species that form schools with few individuals, gears used in coastal lagoons were selective of highly mobile pelagic species that form large schools. We found a low competitive interaction between different gear types, meaning there was a low overlap in trait selectivity between fishing gears. We also found direct associations between gears and fish functional traits: hooks and line targeted species that exhibit limited mobility capabilities, making these species more vulnerable to local levels of fishing effort. In contrast, nets and fish corrals targeted mobile species that exhibited a greater diversity of functional traits. Some of our results contrasted with the current literature on the topic, with differences highlighting the need for more research to clarify global patterns of trait selectivity by gear type. Our results have implications for fisheries management in northeastern Brazil: gear bans and effort caps are commonly used management measures that can foster fisheries sustainability by minimizing impacts to fish assemblage functions.

Wildfire activity in the western United States has been increasing since the 1970s, with many fires occurring on land managed by government agencies. Over six million acres of public lands are surrounded by private land and lack road access, making them legally inaccessible to federal and state agencies and potentially constraining management and suppression of wildfires. In this paper, we assemble data on all fires that started on public lands in the western US over the period 1992–2015 and estimate the effect of legal accessibility on fire size. We find that ignitions are 14%–23% more likely to become large (greater than one acre) if they occur on inaccessible land. We provide evidence that this effect may be driven in part by agencies’ inability to conduct fuels management and in part by slower suppression responses on legally inaccessible land. Our results suggest that wildfire prevention and suppression could be bolstered by improved access to public lands and underscore the need for ongoing research on the relationship between land ownership and wildfire.

Estimates of global economic damage caused by carbon dioxide (CO₂) emissions can inform climate policy^1,2,3. The social cost of carbon (SCC) quantifies these damages by characterizing how additional CO₂ emissions today impact future economic outcomes through altering the climate^4,5,6. Previous estimates have suggested that large, warming-driven increases in energy expenditures could dominate the SCC^7,8, but they rely on models^9,10,11 that are spatially coarse and not tightly linked to data^{2,3,6,7,12,13}. Here we show that the release of one ton of CO₂ today is projected to reduce total future energy expenditures, with most estimates valued between −US$3 and −US$1, depending on discount rates. Our results are based on an architecture that integrates global data, econometrics and climate science to estimate local damages worldwide. Notably, we project that emerging economies in the tropics will dramatically increase electricity consumption owing to warming, which requires critical infrastructure planning. However, heating reductions in colder countries offset this increase globally. We estimate that 2099 annual global electricity consumption increases by about 4.5 exajoules (7 per cent of current global consumption) per one-degree-Celsius increase in global mean surface temperature (GMST), whereas direct consumption of other fuels declines by about 11.3 exajoules (7 per cent of current global consumption) per one-degree-Celsius increase in GMST. Our finding of net savings contradicts previous research^7,8, because global data indicate that many populations will remain too poor for most of the twenty-first century to substantially increase energy consumption in response to warming. Importantly, damage estimates would differ if poorer populations were given greater weight¹⁴.

With human food production a major driver of global environmental change, there is increasing recognition of the importance of shifting towards more sustainable dietary patterns. With wholesale dietary change notoriously difficult to implement at scale, various new food analogues have emerged to serve as qualitatively similar (e.g. taste, texture) but lower environmental impact alternatives for existing foods, particularly animal protein. While new foods may have low environmental impacts, very little is known about how reliably new products drive the disadoption (permanently reduced or ceased consumption) of existing foods. Using simple models of the interplay between adoption levels, substitution ratios of new and existing foods, and different products targeted for replacement, we explore the role of food disadoption on the global warming potential of protein consumption by a theoretical human population. We show how counterintuitive changes to the total environmental impacts attributable to food consumption are plausible following widespread uptake of ‘sustainable’ new foods if they do not reliably drive the disadoption of existing high-impact alternatives. Greater empirical evidence of how effectively new foods drive the disadoption of their intended targets is needed to prevent mass development of alternatives that exacerbate the environmental impact of human diets.

Market approaches to environmental conservation, by which mechanisms such as property rights, prices, and contracts are used to advance environmental goals, have gained traction globally in recent decades (1). But in many cases, antiquated rules limit their role in conserving public natural resources. “Use-it-or-lose-it” requirements, together with narrow definitions of eligible “uses,” can preclude environmental groups from participating in markets for natural resources. These restrictions can bias resource management in favor of extractive users, even when conservation interests are willing to pay more to protect resources from development. We argue that acquisition of public natural resource rights for the purpose of withholding them from development should be allowed. Policies should be reformed to include conservation as a legally valid form of “use.” Allowing such “nonuse rights” to public natural resources would enable markets to advance environmental goals, leading to more stable and less contentious outcomes.

A growing number of companies have announced zero-deforestation commitments (ZDCs) to eliminate commodities produced at the expense of forests from their supply chains. Translating these aspirational goals into forest conservation requires forest mapping and monitoring (M&M) systems that are technically adequate and therefore credible, salient so that they address the needs of decision makers, legitimate in that they are fair and unbiased, and scalable over space and time. We identify 12 attributes of M&M that contribute to these goals and assess how two prominent ZDC programs, the Amazon Soy Moratorium and the High Carbon Stock Approach, integrate these attributes into their M&M systems. These programs prioritize different attributes, highlighting fundamental trade-offs in M&M design. Rather than prescribe a one-size-fits-all solution, we provide policymakers and practitioners with guidance on the design of ZDC M&M systems that fit their specific use case and that may contribute to more effective implementation of ZDCs.

Environmental markets are widely prescribed as an alternative to open access regimes for natural resources. We develop a model of dynamic groundwater extraction to demonstrate how a spatial regression discontinuity design that exploits a spatially incomplete market for groundwater rights recovers a lower bound on the market’s net benefit. We apply this estimator to a major aquifer in water-scarce southern California and find that a groundwater market generated substantial net benefits, as capitalized in land values. Heterogeneity analyses point to gains arising in part from rights trading, enabling more efficient water use across sectors. Additional findings suggest that the market increased groundwater levels.

Combining satellite imagery with machine learning (SIML) has the potential to address globalchallenges by remotely estimating socioeconomic and environmental conditions in data-poorregions, yet the resource requirements of SIML limit its accessibility and use. We show that asingle encoding of satellite imagery can generalize across diverse prediction tasks (e.g., forestcover, house price, road length). Our method achieves accuracy competitive with deep neuralnetworks at orders of magnitude lower computational cost, scales globally, delivers labelsuper-resolution predictions, and facilitates characterizations of uncertainty. Since imageencodings are shared across tasks, they can be centrally computed and distributed tounlimited researchers, who need only fit a linear regression to their own ground truth data inorder to achieve state-of-the-art SIML performance.

In 2017 and 2018, wildfires in California burned millions of hectares and caused billions of dollars in structure damages. This paper puts these recent fires in a long-term historical context by assembling four decades of data on wildfires in California. We combine administrative data of structure loss due to wildfire with economic data on replacement costs and spatial data on fire locations and sizes. We find that over the period 1979–2018, wildfires in California have been getting larger and that the trend is accelerating. This same trend is seen in the wildland–urban interface. As well, total structure damage from wildfires has grown steadily during the past four decades. Our conclusion is that the recent California fires are not an anomaly, but rather part of a trend towards larger and increasingly destructive wildfires.

Marine protected areas (MPAs) cover 3–7% of the world's ocean, and international organizations call for 30% coverage by 2030. Although numerous studies show that MPAs produce conservation benefits inside their borders, many MPAs are also justified on the grounds that they confer conservation benefits to the connected populations that span beyond their borders. A network of MPAs covering roughly 20% of the Channel Islands National Marine Sanctuary was established in 2003, with a goal of providing regional conservation and fishery benefits. We used a spatially explicit bioeconomic simulation model and a Bayesian difference-in-difference regression to examine the conditions under which MPAs can provide population-level conservation benefits inside and outside their borders and to assess evidence of those benefits in the Channel Islands. As of 2017, we estimated that biomass densities of targeted fin-fish had a median value 81% higher (90% credible interval: 23–148) inside the Channel Island MPAs than outside. However, we found no clear effect of these MPAs on mean total biomass densities at the population level: estimated median effect was –7% (90% credible interval: –31 to 23) from 2015 to 2017. Our simulation model showed that effect sizes of MPAs of <30% were likely to be difficult to detect (even when they were present); smaller effect sizes (which are likely to be common) were even harder to detect. Clearly, communicating expectations and uncertainties around MPAs is critical to ensuring that MPAs are effective. We provide a novel assessment of the population-level effects of a large MPA network across many different species of targeted fin-fish, and our results offer guidance for communities charged with monitoring and adapting MPAs.