Our research focuses on questions related to wildlife conservation, resource use and environmental quality.


Weather extremes like droughts and heat waves are becoming increasingly frequent worldwide, with severe consequences for agricultural production and food security. Although the effects of such events on the production of major crops is well-documented, the response of a larger pool of crops is unknown and the potential of crop diversity to buffer agricultural outputs against weather extremes remains untested. Here, we evaluate whether increasing the diversity of crop portfolios at the country level confers greater resistance to a country's overall yield and revenues against losses to droughts and high temperatures. To do this, we use 58 years of annual data on weather, crop yields and agricultural revenues for 109 crops in 127 countries. We use the spatial distribution of each crop and their cropping cycle to determine their exposure to weather events. We find that growing greater crop diversity within countries reduces the negative impacts of droughts and high temperatures on agricultural outputs. For drought, our results suggest that the effect is explained not only by crop diversity itself, but also by the sensitivity of the most abundant crops (in terms of harvested areas) to this extreme. Countries dedicating more land to minor, drought-tolerant crops reduce the average sensitivity of country-scale crop portfolios and show greater resistance of yield and revenues to drought. Our study highlights the unexploited potential for putting crop biodiversity to work for greater resilience to weather, specifically in poorer developing countries that are likely to suffer disproportionately from climate change impacts.


This paper reports on the universe of garment-making-firm owners in a Ghanaian district capital during the COVID-19 crisis. By July 2020, 80 percent of both male- and female-owned firms were operational. However, pre-pandemic data show that selection into persistent closure differs by gender. Consistent with a “cleansing effect” of recessions and highlighting the presence of marginal female entrepreneurs, female-owned firms that remain closed past the spring lockdown are negatively selected on pre-pandemic sales. The pre-pandemic sales distributions of female survivors and non-survivors are significantly different from each other. Female owners of non-operational firms exit to non-employment and experience large decreases in overall earnings. In contrast, persistently closed male-owned firms are not selected on pre-pandemic firm characteristics. Instead, male non-survivors are 36 percentage points more likely than male survivors to have another income-generating activity prior to the crisis. Male owners of persistently closed firms fully compensate for revenue losses in their core businesses with earnings from these alternative income-generating activities. Taken together, the evidence is most consistent with differential underlying occupational choice fundamentals for self-employed men and women in this context.


As we retreated to our dwellings in the “anthropause” of spring 2020, were the wildlife sightings in previously crowded spaces a reclamation of habitat, or a mere increase in detection? We leverage an increase in balcony birdwatching, a million eBird entries, and difference-in-difference techniques to test if urban avian species richness rose during India's COVID-19 lockdown. Controlling for effort, birdwatchers in the 20 most populous cities observed a 16% increase in the number of species during lockdown. While human activity stopped overnight, and noise and visual pollution decreased soon after, increased species diversity was observed 1–2 weeks later; evidence that gradual population recovery, not better detection, underlay our results. We find at-risk, and rare, species among those reclaiming cities, implying that reducing human disturbance in urban areas can protect threatened species. Increased species diversity likely derives from a reduction in noise and air pollution associated with the lockdown, implying that urban planners should consider conservation co-benefits of urban policies when designing sustainable cities.


Agriculture is a major threat to global biodiversity. A common claim is that large-scale agro-industrial farming is mainly responsible for the biodiversity decline, while smaller family farms are more wildlife friendly. Here we leverage a natural experiment along the former inner German border to estimate the causal impact of farm size on biodiversity. We combine land cover data with bird diversity data to establish the mechanisms through which farm size affects bird diversity. Our main results show that the increase in farm size at the former inner German border reduces bird diversity by 15%. The results suggest further that the decline is the result of land cover simplification rather than land use intensification.


Rural to urban migration (RUM) is a key component of economic development, but its environmental consequences are not well understood. Here, we study the impacts of RUM on agriculture and land use using household panel data in combination with tree cover data from Uganda. Our results show that the labor loss and the inflow of remittances from RUM lead to a reduction in crop diversity but no shift toward less labor-intensive crops or crops with a high up-front investment. In addition to those results at the intensive margin, we find a reduction of cultivated area at the household level, which translates into reduced tree cover loss at the district level. These results suggest an important but nuanced role of RUM for land use change.



Agricultural production has increased dramatically in the past 50 years, supported, in part, by the simplification of agricultural landscapes. While the benefits of increased food production are difficult to dispute, simplification, at both the local and landscape level, has fuelled declines in biodiversity and ecosystem services. In addition to the concerns that this loss of complexity necessitates higher levels of pesticide use in general, local and landscape simplification may also increase pest outbreaks and, consequently, infrequent but particularly high pesticide use with potentially damaging consequences for the environment and human health. We find that increasing cropland in the landscape—and larger fields generally—increase the level and variability of pesticide use while crop diversity has the opposite effect, as predicted by ecological theory. In all cases, accounting for non-random planting decisions and farmer-specific behaviour strongly influences the magnitude of the estimated statistical relationships. This suggests that, while complexity increases stability and reduces high deviations in insecticide use, accounting for crop and farmer-specific characteristics is crucial for statistical inference and sound scientific understanding.


In Spring 2020, COVID-19 led to an unprecedented halt in public and economic life across the globe. In an otherwise tragic time, this provides a unique natural experiment to investigate the environmental impact of such a (temporary) 'de-globalization'. Here, we estimate the medium-run impact of a battery of COVID-19 related lockdown measures on air quality across 162 countries, going beyond the existing short-run estimates from a limited number of countries. In doing so, we leverage a new dataset categorizing lockdown measures and tracking their implementation and release, extending to 31 August 2020. We find that domestic and international lockdown measures overall led to a decline in PM2.5 pollution by 45% and 35%, respectively. This substantial impact persists in the medium-run, even as lockdowns are lifted, there is, however, substantial heterogeneity across different types of lockdown measures, different countries, and different sources of pollution. We show that some country trajectories are much more appealing (with fewer COVID-19 casualties, less economic downturn and bigger pollution reductions) than others. Our results have important policy implications and highlight the potential to 'build back better' a sustainable economy where pollution can be curbed in a less economically costly way than during the COVID-19 pandemic.


Reducing the costs from human–wildlife conflict, mostly borne by marginal rural households, is a priority for conservation. We estimate the mean species-specific cost for households suffering damages from one of 15 major species of wildlife in India. Our data are from a survey of 5,196 households living near 11 wildlife reserves in India, and self-reported annual costs include crop and livestock losses and human casualties (injuries and death). By employing conservative estimates from the literature on the value of a statistical life (VSL), we find that costs from human casualties overwhelm crop and livestock damages for all species associated with fatalities. Farmers experiencing a negative interaction with an elephant over the last year incur damages on average that are 600 and 900 times those incurred by farmers with negative interactions with the next most costly herbivores: the pig and the nilgai. Similarly, farmers experiencing a negative interaction with a tiger over the last year incur damage that is on average 3 times that inflicted by a leopard and 100 times that from a wolf. These cost differences are largely driven by differences in the incidence of human death and casualties. Our estimate of costs fluctuates across reserves, mostly due to a variation of human casualties. Understanding the drivers of human casualties and reducing their incidence are crucial to reducing the costs from human–wildlife conflict.




Abstract: British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act.

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Abstract: The Paris Agreement aims to mitigate the potential impacts of climate change on ecological and social systems. Using an ensemble of climate-marine ecosystem and economic models, we explore the effects of implementing the Agreement on fish, fishers, and seafood consumers worldwide. We find that implementing the Agreement could protect millions of metric tons in annual worldwide catch of top revenue-generating fish species, as well as billions of dollars annually of fishers’ revenues, seafood workers’ income, and household seafood expenditure. Further, our analysis predicts that 75% of maritime countries would benefit from this protection, and that ~90% of this protected catch would occur within the territorial waters of developing countries. Thus, implementing the Paris Agreement could prove to be crucial for the future of the world’s ocean ecosystems and economies.

Link to Article.