Critical Uncertainties Research Articles

Migration crisis in the EU: developing a framework for analysis of national security and defence strategies

This article addresses migration-security nexus in the EU by assessing Member States’ national security and defence strategies as well as the 2016 EUGS in a time of migration crisis, a crisis that stands as one of the most important geopolitical challenges today in the EU. After developing and applying a framework for analysis derived from a literature review, the existing differences among Member States are clear in terms of strategic cultures and approaches to migration issues. The idea of ‘EU’rope without internal borders is at stake as Schengen is under serious attack due to increasing Eurocentrism and growing extreme right-wing populism, which are a consequence of increasing economic protectionism and international terrorism. The solution seems to depend on two critical uncertainties: the evolution of political and social instability in the North Africa and the Middle East, and the future of the EU itself. The results enlighten a securitization of migration mostly centred on the nation-state and national security rather than on people and human security.

Modeling cold soak evaporative vapor emissions from gasoline-powered automobiles using a newly developed method

ABSTRACTVolatile organic compounds (VOCs) evaporate and vent from a vehicle’s fuel tank to its evaporative control system when the vehicle is both driven and parked. VOCs making it past the control system are emissions. Driving and parking activity, fuel volatility, and temperature strongly affect vapor generation and the effectiveness of control technologies, and the wide variability in these factors and the sensitivity of emissions to these factors make it difficult to estimate evaporative emissions at the macro level. Established modeling methods, such as COPERT and MOVES, estimate evaporative emissions by assuming a constant in-use canister condition and consequently contain critical uncertainty when real conditions deviate from that standard condition. In this study, we have developed a new method to model canister capacity as a representative variable, and estimated emissions for all parking events based on semi-empirical functions derived from real-world activity data and laboratory measurements. As compared to chamber measurements collected during this study, the bias of the MOVES diurnal tank venting simulation ranges from −100% to 129%, while the bias for our method’s simulation is 1.4% to 8.5%. Our modeling method is compared to the COPERT and MOVES models by estimating evaporative emissions from a Euro-3/4/5 and a Tier 2 vehicle in conditions representative for Chicago, IL, and Guangzhou, China. Estimates using the COPERT and MOVES methods differ from our method by −56% to 120% and −100% to 25%, respectively. The study highlights the importance for continued modeling improvement of the anthropogenic evaporative emission inventory and for tightened regulatory standards.Implications: The COPERT and MOVES methodologies contain large uncertainties for estimating evaporative emissions, while our modeling method is developed based on chamber measurements to estimate evaporative emissions and can properly address those uncertainties. Modeling results suggested an urgent need to complete evaporative emissions inventories and also indicated that tightening evaporative emission standards is urgently needed, especially for warm areas.

Development and Calibration of a Mathematical Model of Anal Carcinogenesis for High-Risk HIV-Infected Men.

Men who have sex with men who are living with HIV are at highest risk for anal cancer. Our objective was to use empirical data to develop a comprehensive disease simulation model that reflects the most current understanding of anal carcinogenesis, which is uniquely positioned to evaluate future anal cancer screening strategies and provide insight on the unobservable course of the disease. North America. The individual-based simulation model was calibrated leveraging primary data from empirical studies, such as a longitudinal HIV-positive men who have sex with men cohort study [Human Immunodeficiency and Papilloma Virus Research Group (HIPVIRG); n = 247] and the North American AIDS Cohort Collaboration on Research and Design [(NA-ACCORD); n = 13,146]. We used the model to infer unobservable progression probabilities from high-grade precancer to invasive anal cancer by CD4 nadir and human papillomavirus (HPV) genotype. The calibrated model had good correspondence to data on genotype- and age-specific HPV prevalence; genotype frequency in precancer and cancer; and age- and nadir CD4-specific cancer incidence. The model-projected progression probabilities differed substantially by HPV genotype and nadir CD4 status. For example, among individuals with CD4 nadir <200, the median monthly progression probability from a high-grade lesion to invasive cancer was 0.054% (ie, 6.28% 10-year probability) and 0.004% (ie, 0.48% 10-year probability) for men with an HPV-16 infection versus without a detectable HPV infection, respectively. We synthesized existing evidence into a state-of-the-art anal cancer disease simulation model that will be used to quantify the tradeoffs of harms and benefits of alternative strategies, understand critical uncertainties, and inform national anal cancer prevention policy.

A Critical Time for Mercury Science to Inform Global Policy

Mercury is a global pollutant released into the biosphere by varied human activities including coal combustion, mining, artisanal gold mining, cement production, and chemical production. Once released to air, land and water, the addition of carbon atoms to mercury by bacteria results in the production of methylmercury, the toxic form that bioaccumulates in aquatic and terrestrial food chains resulting in elevated exposure to humans and wildlife. Global recognition of the mercury contamination problem has resulted in the Minamata Convention on Mercury, which came into force in 2017. The treaty aims to protect human health and the environment from human-generated releases of mercury curtailing its movement and transformations in the biosphere. Coincident with the treaty's coming into force, the 13th International Conference of Mercury as a Global Pollutant (ICMGP-13) was held in Providence, Rhode Island USA. At ICMGP-13, cutting edge research was summarized and presented to address questions relating to global and regional sources and cycling of mercury, how that mercury is methylated, the effects of mercury exposure on humans and wildlife, and the science needed for successful implementation of the Minamata Convention. Human activities have the potential to enhance mercury methylation by remobilizing previously released mercury, and increasing methylation efficiency. This synthesis concluded that many of the most important factors influencing the fate and effects of mercury and its more toxic form, methylmercury, stem from environmental changes that are much broader in scope than mercury releases alone. Alterations of mercury cycling, methylmercury bioavailability and trophic transfer due to climate and land use changes remain critical uncertainties in effective implementation of the Minamata Convention. In the face of these uncertainties, important policy and management actions are needed over the short-term to support the control of mercury releases to land, water and air. These include adequate monitoring and communication on risk from exposure to various forms of inorganic mercury as well as methylmercury from fish and rice consumption. Successful management of global and local mercury pollution will require integration of mercury research and policy in a changing world.

Reflections in a Distant Mirror: Japanese Corporate Governance through American Eyes

For the last ten years, Japanese corporate governance has served as a distant mirror in whose reflection American academics could better see the attributes of their own system. As scholars came to recognize that the institutional characteristics of the American and Japanese systems were politically and historically contingent, other countries' approaches became serious objects of studies, rather than just way stations on the road to convergence. In this paper, I try to return the favor by holding up the Japanese system to an American mirror. In recent years, exogenous changes have shocked each component of the Japanese corporate governance: for example, weakened banks and corporate access to the global capital market have weakened main bank relations and the banks' ability to monitor corporate performance; a decrease in the number of positions to which lifetime employment attaches due to increased global competition threatens to change the incentives of the next generation of employees. When reflected in an American mirror, this wave of economic change highlights a critical uncertainty concerning the Japanese corporate governance system: what are the instruments of adaptive efficiency in a system structured to support commitment and stability?

Probabilistic Assessment of Investment Options in Honey Value Chains in Lamu County, Kenya

Designing and implementing biodiversity-based value chains can be a complex undertaking, especially in places where outcomes are uncertain and risks of project failure and cost overruns are high. We used the Stochastic Impact Evaluation (SIE) approach to guide the Intergovernmental Authority on Development (IGAD) on viable investment options in honey value chains, which the agency considered implementing as an economic incentive for communities along the Kenya-Somalia border to conserve biodiversity. The SIE approach allows for holistic analysis of project cost, benefit, and risk variables, including those with uncertain and missing information. It also identifies areas that pose critical uncertainties in the project. We started by conducting a baseline survey in Witu and Awer in Lamu County, Kenya. The aim of the survey was to establish the current farm income from beekeeping as a baseline, against which the prospective impacts of intervention options could be measured. We then developed an intervention decision model that was populated with all cost, benefit and risk variables relevant to beekeeping. After receiving training in making quantitative estimates, four subject-matter experts expressed their uncertainty about the proposed variables in the model by specifying probability distributions for them. We then used Monte Carlo simulation to project decision outcomes. We also identified variables that projected decision outcomes were most sensitive to, and we determined the value of information for each variable. The variable with the highest information value to the decision-maker in Witu was the honey price. In Awer, no additional information on any of the variables would change the recommendation to invest in honey value chains in the region. The analysis demonstrates a novel and comprehensive approach to decision-making for different stakeholders in a project where decision outcomes are uncertain.

Critical kinetic uncertainties in modeling hydrogen/carbon monoxide, methane, methanol, formaldehyde, and ethylene combustion

In view of the critical role of the underlying uncertainties of the reaction model in future progress of combustion chemistry modeling, Foundational Fuel Chemistry Model 1.0 (FFCM-1) was developed with uncertainty minimization against available fundamental combustion data of H2, H2/CO, CH4, CH2O, and C2H6. As a critical feature, FFCM-1 not only reconciles a large body of fundamental combustion data, it also has rigorously evaluated uncertainties for the rate coefficients, the combustion experimental targets used for model optimization and uncertainty minimization, and most importantly, an optimized reaction model with quantified uncertainties. In the present work, the remaining kinetic uncertainties of FFCM-1 are examined using a perfectly stirred reactor (PSR) as the relevant model platform for which reliable experiments under the conditions tested are unavailable. The key questions to address include the level of improvement from model optimization in the prediction uncertainties of PSR residence times at extinction and ignition and the rate coefficients of reactions that must be improved in order to reduce the prediction uncertainties. Computational tests are made for H2/CO, CH2O, CH4, CH3OH and C2H4–air mixtures over the pressure range of 10–100 atm and PSR inlet temperatures that would yield residence times comparable to the time scales typical of fuel combustion in practical combustors. The results show that although model optimization reduces the prediction uncertainties of residence time at extinction and ignition, the remaining uncertainties remain rather large. Key reactions for which reduced rate uncertainties would greatly improve the reaction model quality and accuracy have been identified and discussed in detail.

Highly skilled migrants entering the labour market: Experiences and strategies in the contested field of overqualification and skills mismatch

The mobility of highly skilled individuals between EU/EFTA countries is often discussed as either about choice and professional careers or about overqualification and power relations that lead to deskilling. To highlight these issues’ entanglements, this paper draws on in-depth interviews with tertiary-educated Spaniards who migrated to Switzerland for work. Using Bourdieu’s capital approach, we unpack the generic definition of “qualification and skills mismatch”, which is a key issue in young highly skilled migrants’ labour market experiences. In so doing, we reveal the very individual and nuanced meanings of qualification and skills mismatch, including often subtle constraints in the labour market and personal limits imposed by accepting mismatching work arrangements. We thus contribute to the understanding of migration, work experiences, and aspirations in the course of middling transnationalism. Our respondents see mobility both as a phase of freedom with the opportunity to gain experience abroad and one of critical periods and uncertainty in relation to work opportunities. The respondents also perceive themselves as still in transition from higher education to work, and in some cases they see global work experience as a form of capital that can improve their work opportunities in Spain as much as in other countries. We argue that these perceptions help them to cope with periods of uncertainty in the context of work.

A Novel NGO Approach to Facilitate the Adoption of Sustainable Innovations in Low-Income Countries: Lessons from Small-scale Farms in Nicaragua

There are about 500 million small-scale farms in low-income countries on the planet. Farmers have been slow to adopt a threefold set of sustainable agronomic practices known as “conservation agriculture” (CA) that have been shown to double productivity. Our study of a novel CA project in Nicaragua, organized based on principles that counter convention, may point to improved ways of understanding and managing sustainable innovations in low-income countries. In particular, by connecting core ideas from the innovation literature to the literature that explores the role of intermediaries such as NGOs, our case study suggests that the efficacy of NGOs to facilitate the adoption of sustainable innovations by small-scale farmers in these settings may be enhanced if NGOs employ non-centrist approaches in order to address the critical uncertainties associated with such innovations. We discuss how our findings contradict some of long-standing arguments in the literature, and their implications for theory and practice.

Influence of Stochastic Dependence on Small-Disturbance Stability and Ranking Uncertainties

A high level of stochastic dependence (or correlation) exists between different uncertainties (i.e., loads and renewable generation), which is nonlinear and non-Gaussian and it affects power system stability. Accurate modeling of stochastic dependence becomes more important and influential as the penetration of correlated uncertainties (such as renewable generation) increases in the network. The stochastic dependence between uncertainties can be modeled using 1) copula theory and 2) joint probability distributions. These methods have been implemented in this paper and their performances have been compared in assessing the small-disturbance stability of a power system. The value of modeling stochastic dependence with increased renewables has been assessed. Subsequently, the critical uncertainties that most affect the damping of the most critical oscillatory mode have been identified and ranked in terms of their influence using advanced global sensitivity analysis techniques. This has enabled the quantification and identification of the impact of modeling stochastic dependence on the raking of critical uncertainties. The results suggest that multivariate Gaussian copula is the most suitable approach for modeling correlation as it shows consistently low error even at higher levels of renewable energy penetration into the power system.

Decadal differences of the diurnal temperature range in the Aral Sea region at the turn of the century

Changes in the surface air diurnal temperature range (DTR) have been highlighted by the Intergovernmental Panel on Climate Change as critical uncertainties in climate change studies. Due to global and local factors, the regional climate in the Aral Sea region is changing intensively, providing a good case study to give a detailed description of the DTR trend and its spatial variability. Results are based on data from 33 stations at the RIHMI-WDC from 1991 to 2010. The values of DTR in the region range between about 3 °C and 18 °C, with the maxima values being observed in spring and summer. The largest differences between the two decades of the annual mean DTR are observed at the stations closest to the pre-desiccation state of the lake shoreline, especially in the south (0.6 °C dec−1). To the west of the Aral Sea, where the lakeshore has receded less, these differences are also expectedly high considering the decrease in the thermal inertia of the remaining lake (0.4 °C dec−1). To the north-east of the lake, the decadal differences of the annual mean DTR were not significant, but decadal differences of the seasonal DTR were large from February to April (–0.4 °C dec−1) coinciding with the season when the decadal differences of the mean local temperature is of 2 °C dec−1. In the south, where the artificial Sarygamysh Lake expanded during the studied period, the decadal difference of the annual mean DTR is negative. The increase in the mean temperature of all the stations between the two decades is of 0.5 °C dec−1. From August to October, in the southern and the south-eastern parts of the Aral Sea, the increase of the maximum daily temperatures was about 0.1 °C dec−1 larger than the increase of the mean temperatures.

Multidimensional stress test for hydropower investments facing climate, geophysical and financial uncertainty

Abstract Investors, developers, policy makers and engineers are rightly concerned about the potential effects of climate change on the future performance of hydropower investments. Hydroelectricity offers potentially low greenhouse-gas emission, renewable energy and reliable energy storage. However, hydroelectricity developments are large, complicated projects and possibly critically vulnerable to changes in climate and other assumptions related to future uncertainties. This paper presents a general assessment approach for evaluating the resilience of hydroelectricity projects to uncertainty in climate and other risk factors (e.g., financial, natural hazard). The process uses a decision analytic framework based on a decision scaling approach, which combines scenario neutral analysis and vulnerability-specific probability assessment. The technical evaluation process involves identification of project objectives, specification of uncertain factors, multi-dimensional sensitivity analysis, and data mining to identify vulnerability-specific scenarios and vulnerability-specific estimations of risk. The process is demonstrated with an application to a proposed hydropower facility on the Arun River in Nepal. The findings of the case study illustrate an example in which climate change is not the critical future uncertainty, and consequently highlight the importance of considering multiple uncertainties in combination.

A comparison of land use change accounting methods: seeking common grounds for key modeling choices in biofuel assessments

Five currently used methods to account for the global warming (GW) impact of the induced land-use change (LUC) greenhouse gas (GHG) emissions have been applied to four biofuel case studies. Two of the investigated methods attempt to avoid the need of considering a definite occupation –thus amortization– period by considering ongoing LUC trends as a dynamic baseline. This leads to the accounting of a small fraction (0.8%) of the related emissions from the assessed LUC, thus their validity is disputed. The comparison of methods and contrasting case studies illustrated the need of clearly distinguishing between the different time horizons involved in life cycle assessments (LCA) of land-demanding products like biofuels. Absent in ISO standards, and giving rise to several confusions, definitions for the following time horizons have been proposed: technological scope, inventory model, impact characterization, amortization/occupation, plantation lifetime and harvesting frequency. It is suggested that the anticipated technical lifetime of biorefineries using energy crops as feedstock stands as the best proxy for the cut-off criterion of land's occupation period and the inventory modeling period. Top-down LUC models are suggested as a gross reference benchmark to evaluate LUC results from bottom-up models, since the former represent average GHG emissions from deforestation statistics at different spatial resolutions. Reporting LUC emissions per area and implementing a corporate accounting system that ascribes deforestation emissions to responsible companies could avoid the critical uncertainty related to yield estimations.

Metacommunities, metaecosystems and the environmental fate of chemical contaminants

Abstract Although pollution is a major driver of ecosystem change, models predicting the environmental fate of contaminants suffer from critical uncertainties related to oversimplifying the dynamics of the biological compartment. It is increasingly recognized that contaminant processing is an outcome of ecosystem functioning, that ecosystem functioning is contingent on community structure and that community structure is influenced by organismal dispersal. We propose a conceptual organization of the contribution of organismal dispersal to local contaminant fate. Direct dispersal effects occur when the dispersing organism directly couples contaminant stocks in spatially separate ecosystems by transporting contaminants in its biomass. Indirect dispersal effects occur when the dispersing organism indirectly influences contaminant fate via community assembly. This can occur either when the dispersing organism is a contaminant processor or when the dispersing organism alters, via species interactions, the abundance of contaminant biotransporters or processors already established in the ecosystem. The magnitude of direct and indirect dispersal effects is modulated by many factors, including other contaminants. These will influence population growth rates of the dispersing species in the donor ecosystem, or the probability that a dispersing individual reaches the recipient ecosystem. We provide a review of pertinent literature demonstrating that these two mechanisms, and their chemical modulation, are well supported or likely to occur in many natural and human‐modified landscapes. The literature also demonstrates that they can operate in concert with each other. Synthesis and applications. Managed ecosystems thought to be important contaminant and nutrient sinks, such as artificial ponds and constructed wetlands, should be monitored and controlled for in‐and‐out animal movement if contaminant export is found to be relevant. Uncontaminated fishing grounds linked to contaminated sites via movement of dispersing species should be monitored and resident species evaluated for health consumption advisories. Assessing the success of contaminated site remediation can be improved by better matching the spatial extent of site remediation and the home range of monitored species. Finally, interagency research fund programmes should be developed that narrow the current gap between the fields of ecology and ecotoxicology.

Light scattering, aerosols, clouds, climate, Hendrik van de Hulst, and I

It is not often that I have the opportunity to write something that is not a scientific paper, and I am thankful for this opportunity to express my thoughts with regard to pursuits that are greater than those of science. In this van de Hulst essay, to honor Hendrik van de Hulst, I briefly summarize a few points from Hendrik's life that I find especially interesting, including his interests in spiritual (or religious) aspects of life, and his decision to avoid involvement in nucleation problems, a critical and basic uncertainty of current climate models. After that, I present briefly a few episodes from my own experiences as an apprentice of science and life.

Physical feasibility of biochar production and utilization at a farm-scale: A case-study in non-irrigated seed production

Despite many demonstrated benefits that biochars can have on agricultural soils, there are few examples of profitable biochar utilization on commercial farms. Barriers to profitability include successfully pairing waste streams, production facilities, and farms where biochar is utilized. However, farm-scale biochar systems, which utilize agricultural wastes as feedstocks and produce energy and biochar for on-farm use, may have efficiency advantages over regional, industrial biochar production. Two critical uncertainties for the feasibility of on-farm production are 1) whether a biochar can be produced from on-farm feedstocks with appropriate qualities for soil amendment, and 2) whether on-farm feedstocks are sufficiently abundant to meet on-farm demand. Here we evaluate these issues for a farm-scale gasification system in NE Washington State that produces biochar from grass seed screenings and straw. Field trials to evaluate the biochar as a liming alternative found it was highly effective when broadcast at a rate of at least 18 Mg ha−1. Biochar outperformed hydrated lime in the first year of the study and improved yields by a factor of 2.88 across both years. Biochar produced from on-farm feedstocks were sufficient to amend 6.3–11.8% of the production area annually, translating to a return interval of 9–16 years. Potential co-production of electrical power far exceeded on-farm demand for operating a seed cleaning mill. We conclude that an on-farm biochar production system is physically feasible for meeting demands for both power and liming amendments.

Elevated moisture stimulates carbon loss from mineral soils by releasing protected organic matter

Moisture response functions for soil microbial carbon (C) mineralization remain a critical uncertainty for predicting ecosystem-climate feedbacks. Theory and models posit that C mineralization declines under elevated moisture and associated anaerobic conditions, leading to soil C accumulation. Yet, iron (Fe) reduction potentially releases protected C, providing an under-appreciated mechanism for C destabilization under elevated moisture. Here we incubate Mollisols from ecosystems under C3/C4 plant rotations at moisture levels at and above field capacity over 5 months. Increased moisture and anaerobiosis initially suppress soil C mineralization, consistent with theory. However, after 25 days, elevated moisture stimulates cumulative gaseous C-loss as CO2 and CH4 to >150% of the control. Stable C isotopes show that mineralization of older C3-derived C released following Fe reduction dominates C losses. Counter to theory, elevated moisture may significantly accelerate C losses from mineral soils over weeks to months—a critical mechanistic deficiency of current Earth system models.

US liquefied natural gas (LNG) exports: Boom or bust for the global climate?

Abstract Due to surging natural gas production, the United States is now a growing exporter of liquefied natural gas (LNG) to overseas destinations. However, the potential greenhouse gas implications from increased US natural gas remain unclear. Through a hybrid lifecycle energy strategy analysis, we investigate potential greenhouse gas scenarios of US LNG exports to Asia, the largest source of global LNG demand. We find that the climate impacts of US exports to China, Japan, India, and South Korea could vary tremendously. Annual global lifecycle emissions range from −32 to +63 million metric tons CO2e per billion cubic feet (Bcf) per day of exports. Despite this range, emissions are not likely to decrease and may increase significantly due to greater global energy consumption, higher emissions in the US, and methane leakage. However, international climate obligations are a critical uncertainty underlying all emissions estimates. Our results indicate the need for further research into quantifying the climate impacts of LNG exports, and energy exports more generally.

Mapping the Stakeholders: Using Social Network Analysis to Increase the Legitimacy and Transparency of Participatory Scenario Planning

ABSTRACTParticipatory scenario planning (PSP) processes rely on accurate stakeholder identification to develop a key set of critical uncertainties. While many stakeholder analysis methods are able to identify stakeholders and describe their relationships, we found these efforts to have limited use in the fast-moving and in-depth approach of PSP research. We find that social network analysis (SNA) is an efficient, objective, and transparent approach to stakeholder identification in highly contested natural resource management issues. We present a case study of our research on Alaska’s Kenai Peninsula to describe how SNA’s ability to contextualize the relations between actors can benefit participatory research.

The value of information for woodland management: updating a state–transition model

AbstractValue of information (VOI) analyses reveal the expected benefit of reducing uncertainty to a decision maker. Most ecological VOI analyses have focused on population models rarely addressing more complex community models. We performed a VOI analysis for a complex state–transition model of Box‐Ironbark Forest and Woodland management. With three management alternatives (limited harvest/firewood removal (HF), ecological thinning (ET), and no management), managing the system optimally (for 150 yr) with the original information would, on average, increase the amount of forest in a desirable state from 19% to 35% (a 16‐percentage point increase). Resolving all uncertainty would, on average, increase the final percentage to 42% (a 19‐percentage point increase). However, only resolving the uncertainty for a single parameter was worth almost two‐thirds the value of resolving all uncertainty. We found the VOI to depend on the number of management options, increasing as the management flexibility increased. Our analyses show it is more cost‐effective to monitor low‐density regrowth forest than other states and more cost‐effective to experiment with the no‐management alternative than the other management alternatives. Importantly, the most cost‐effective strategies did not include either the most desired forest states or the least understood management strategy, ET. This implies that managers cannot just rely on intuition to tell them where the most VOI will lie, as critical uncertainties in a complex system are sometimes cryptic.