Prospect theory and energy efficiency

Investments in energy efficiency entail uncertainty, and when faced with uncertainty consumers have been shown to behave according to prospect theory: preferences are reference-dependent and exhibit loss aversion, and probabilities are subjectively weighted. Using data from a choice experiment eliciting prospect theory parameters, I provide evidence that loss-averse people are less likely to invest in energy efficiency. Then, I consider policy design under prospect theory when there are also externalities from energy use. A higher degree of loss aversion implies a higher subsidy to energy efficiency. Numerical simulations suggest that the impact of prospect theory on policy may be substantial.     

Does subway expansion improve air quality?

Major cities in China and many other fast-growing economies are expanding their subway systems in order to address worsening air pollution and traffic congestion. This paper quantifies the impact of subway expansion on air quality by leveraging fine-scale air quality data and the rapid build-out of 14 new subway lines and 252 stations in Beijing from 2008 to 2016. Our main empirical framework examines how the density of the subway network affects air quality across different locations in the city during this period. To address the potential endogenous location of subway stations, we construct an instrument based on historical subway planning, long before air pollution and traffic congestion were of concern. Our analysis shows that an increase in subway density by one standard deviation improves air quality by two percent and the result is robust to a variety of alternative specifications including the distance-based difference-in-differences method. The total discounted health benefit during a 20-year period from reduced mortality and morbidity as a result of 14 new subway lines amounts to $1.0–3.1 billion, or only 1.4–4.4 percent of the total construction and operating cost.     

模拟酸雨对北亚热带天然次生林土壤呼吸的影响

于2009年3月～2010年1月在南京市郊龙王山北亚热带天然次生林进行模拟酸雨试验,以便携式土壤CO2通量观测仪对不同酸雨强度处理下的林地土壤呼吸速率进行原位测定,研究酸雨对森林土壤呼吸的影响.结果表明,在本试验阶段,4个酸雨强度处理CK(pH值6.4,去离子水)、T1(pH值4.5)、T2(pH值3.5)、T3(pH值2.5)的平均土壤呼吸速率分别为(3.20±0.21)、(3.34±0.30)、(3.51±0.06)、(2.99± 0.23)μmol/(m2·s),酸雨各处理的土壤呼吸季节变化规律显著.由于森林植被生长期季节变化明显,将其分为非生长季1(2~4月)、生长季(5~10月)、非生长季2(11月~次年1月)3个阶段.配对t检验分析各阶段土壤呼吸速率的结果表明,在非生长季1,模拟酸雨未抑制土壤呼吸作用,T1和T2酸雨处理反而促进了土壤呼吸作用;在生长季,高强度模拟酸雨T3显著抑制了土壤呼吸作用;在非生长季2,也出现了模拟酸雨促进土壤呼吸作用的现象;对于整个观测阶段而言,低强度模拟酸雨处理未显著改变北亚热带天然次生林的土壤呼吸,仅高强度模拟酸雨T3显著抑制了土壤呼吸作用.不同酸雨强度处理下的土壤呼吸速率与土壤温度的指数回归关系均达显著水平(P<0.01),CK、T1、T2、T3处理的Q10值分别为3.04,2.73,2.83,2.51,模拟酸雨处理降低了北亚热带天然次生林土壤呼吸的温度敏感性.     

30种离子液体对青海弧菌Q67的毒性效应

应用微板毒性分析法系统地考察了30种具有不同烷基链长度、阴离子基团和阳离子骨架(甲基咪唑、二甲基咪唑和吡啶)的“绿色溶剂”离子液体(ionic liquids,ILs)对一种新型淡水发光菌青海弧菌Q67 (Vibrio qinghaiensis sp. Q67)的毒性效应.非线性拟合结果表明,Logit或Weibull函数可有效地表征30种ILs的剂量-效应曲线,其相关系数R>0.98,均方根误差RMSE<0.053;30种ILs对Q67的毒性差异很大,pEC₅₀值在1.01～5.48之间;ILs对Q67的毒性具有烷基链效应,且烷基链上每增加2个碳原子,其pEC₅₀值增加近1倍;ILs的阴离子基团、阳离子骨架及ILs本身的吸光性不显著影响ILs对发光菌Q67的毒性.     

温度和水分对中亚热带人工林生态系统呼吸的调控作用

全球气候变化导致的降水格局改变影响陆地生态系统碳收支状况。陆地生态系统所固定的碳主要通过呼吸作用返回到大气中,而温度和水分是调节生态系统呼吸的重要因素。ChinaFLUX千烟洲中亚热带人工林通量站夏季雨热不同季而造成的季节性干旱为探讨温度和水分对生态系统呼吸的调控作用提供了天然的试验条件。研究利用该生态系统2003-2010年涡度相关和常规气象数据,阐述了生态系统呼吸对温度和土壤含水量的响应特征,对比分析了只考虑温度与同时考虑温度和土壤含水量对生态系统呼吸的季节模式和年呼吸量的影响。研究表明,生态系统呼吸的季节变异主要受土壤温度的控制,呈现指数响应特征。但是,在干旱胁迫条件下,土壤含水量对生态系统呼吸的季节变异起到明显的调控作用。参考温度下的生态系统呼吸(R_ref)明显受土壤含水量的影响。生态系统年呼吸量为1 289.4±73.9 gC·m^-2·a^-1,两类模型的估算结果没有显著差异。但是在生态系统的季节变异上,两类模型估算存在显著差异,同时考虑温度与土壤含水量的模型更适合模拟遭受干旱胁迫的生态系统呼吸。     

Toward an integrative molecular approach to wildlife disease

Pathogens pose serious threats to human health, agricultural investment, and biodiversity conservation through the emergence of zoonoses, spillover to domestic livestock, and epizootic outbreaks. As such, wildlife managers are often tasked with mitigating the negative effects of disease. Yet, parasites form a major component of biodiversity that often persist. This is due to logistical challenges of implementing management strategies and to insufficient understanding of host–parasite dynamics. We advocate for an inclusive understanding of molecular diversity in driving parasite infection and variable host disease states in wildlife systems. More specifically, we examine the roles of genetic, epigenetic, and commensal microbial variation in disease pathogenesis. These include mechanisms underlying parasite virulence and host resistance and tolerance, and the development, regulation, and parasite subversion of immune pathways, among other processes. Case studies of devil facial tumor disease in Tasmanian devils (Sarcophilus harrisii) and chytridiomycosis in globally distributed amphibians exemplify the broad range of questions that can be addressed by examining different facets of molecular diversity. For particularly complex systems, integrative molecular analyses present a promising frontier that can provide critical insights necessary to elucidate disease dynamics operating across scales. These insights enable more accurate risk assessment, reconstruction of transmission pathways, discernment of optimal intervention strategies, and development of more effective and ecologically sound treatments that minimize damage to the host population and environment. Such measures are crucial when mitigating threats posed by wildlife disease to humans, domestic animals, and species of conservation concern.     

Firms' and states’ responses to laxer environmental standards

On June 1, 2017, President Trump announced the United States' withdrawal from the Paris agreement on climate change. Despite this decision, American firms continued investing in low-carbon technologies and some states committed to tougher environmental standards. To understand this apparent paradox, this paper studies how a weakening of environmental standards affects the behavior of profit-maximizing firms. It finds that a relaxation of emission standards (i) may increase firms’ incentives to adopt clean technologies, but not to pollute less; (ii) may negatively affect industry profitability if it is perceived as temporary; and, when this is the case, (iii) the unilateral adoption of stricter standards by large states may increase the expected profitability of every firm.     

Microclimate effects of wind farms on local crop yields

This paper considers a novel spillover effect of wind farms - microclimate impacts on neighboring crop yields. Using US county-level crop and wind capacity data, I examine the effects of wind energy development on crop yields, controlling for time-invariant county characteristics and state-level annual shocks. I find robust evidence that counties with increased wind power development have also experienced increased corn and other crop yields, such that an additional 100 MW of wind capacity increases county yields by roughly 1%. At recent prices, this implies a more than $5 dollar per megawatt-hour local benefit, corresponding to several hundred million dollars in annual benefits.     

Strategic implications of counter-geoengineering: Clash or cooperation?

Solar geoengineering has received increasing attention as an option to temporarily stabilize global temperatures. A key concern is that heterogeneous preferences over the optimal amount of cooling combined with low deployment costs may allow the country with the strongest incentive for cooling, the so-called free-driver, to impose a substantial externality on the rest of the world. We analyze whether the threat of counter-geoengineering technologies capable of negating the climatic effects of solar geoengineering can overcome the free-driver problem and tilt the game in favour of international cooperation. Our game-theoretical model of countries with asymmetric preferences allows for a rigorous analysis of the strategic interaction surrounding solar geoengineering and counter-geoengineering. We find that counter-geoengineering prevents the free-driver outcome, but not always with benign effects. The presence of counter-geoengineering leads to either a climate clash where countries engage in a non-cooperative escalation of opposing climate interventions (negative welfare effect), a moratorium treaty where countries commit to abstain from either type of climate intervention (indeterminate welfare effect), or cooperative deployment of solar geoengineering (positive welfare effect). We show that the outcome depends crucially on the degree of asymmetry in temperature preferences between countries.     

Threats to biodiversity from cumulative human impacts in one of North America's last wildlife frontiers

Land‐use change is the largest proximate threat to biodiversity yet remains one of the most complex to manage. In British Columbia (BC), where large mammals roam extensive tracts of intact habitat, continued land‐use development is of global concern. Extant mammal diversity in BC is unrivalled in North America owing, in part, to its unique position at the intersection of alpine, boreal, and temperate biomes. Despite high conservation values, understanding of cumulative ecological impacts from human development is limited. Using cumulative‐effects‐assessment (CEA) methods, we assessed the current human footprint over 16 regional ecosystems and 7 large mammal species. Using historical and current range estimates of the mammals, we investigated impacts of human land use on species’ persistence. For ecosystems, we found that bunchgrass, coastal Douglas fir, and ponderosa pine have been subjected to over 50% land‐use conversion, and over 85% of their spatial extent has undergone either direct or estimated indirect impacts. Of the mammals we considered, wolves were the least affected by land conversion, yet all species had reduced ranges compared with historical estimates. We found evidence of a hard trade‐off between development and conservation, most clearly for mammals with large distributions and ecosystems with high levels of conversion. Rather than serve as a platform to monitor species decline, we strongly advocate these data be used to inform land‐use planning and to assess current conservation efforts. More generally, CEAs offer a robust tool to inform wildlife and habitat conservation at scale.