Stockholm Environment Institute

Global environmental change and sustainability science increasingly recognize the need to address the consequences of changes taking place in the structure and function of the biosphere. These changes raise questions such as: Who and what are vulnerable to the multiple environmental changes underway, and where? Research demonstrates that vulnerability is registered not by exposure to hazards (perturbations and stresses) alone but also resides in the sensitivity and resilience of the system experiencing such hazards. This recognition requires revisions and enlargements in the basic design of vulnerability assessments, including the capacity to treat coupled human-environment systems and those linkages within and without the systems that affect their vulnerability. A vulnerability framework for the assessment of coupled human-environment systems is presented.

Abstract The Water Evaluation and Planning Version 21 (WEAP21) Integrated Water Resource Management (IWRM) model seamlessly integrates water supplies generated through watershed-scale hydrologic processes with a water management model driven by water demands and environmental requirements and is governed by the natural watershed and physical network of reservoirs, canals, and diversions. This version (WEAP21) extends the previous WEAP model by introducing the concept of demand priorities and supply preferences, which are used in a linear programming heuristic to solve the water allocation problem as an alternative to multi-criteria weighting or rule-based logic approaches. WEAP21 introduces a transparent set of model objects and procedures that can be used to analyze a full range of issues faced by water planners through a scenario-based approach. These issues include climate variability and change, watershed condition, anticipated demands, ecosystem needs, the regulatory environment, operational objectives, and available infrastructure.

Despite three decades of political efforts and a wealth of research on the causes and catastrophic impacts of climate change, global carbon dioxide emissions have continued to rise and are 60% higher today than they were in 1990. Exploring this rise through nine thematic lenses—covering issues of climate governance, the fossil fuel industry, geopolitics, economics, mitigation modeling, energy systems, inequity, lifestyles, and social imaginaries—draws out multifaceted reasons for our collective failure to bend the global emissions curve. However, a common thread that emerges across the reviewed literature is the central role of power, manifest in many forms, from a dogmatic political-economic hegemony and influential vested interests to narrow techno-economic mindsets and ideologies of control. Synthesizing the various impediments to mitigation reveals how delivering on the commitments enshrined in the Paris Agreement now requires an urgent and unprecedented transformation away from today's carbon- and energy-intensive development paradigm.

This article provides an overview of how generalised multi-regional input–output models can be used for carbon footprint applications. We focus on the relevance and suitability of such evidence to inform decision making. Such an overview is currently missing. Drawing on UK results, we cover carbon footprint applications in seven areas: national emissions inventories and trade, emission drivers, economic sectors, supply chains, organisations, household consumption and lifestyles as well as sub-national emission inventories. The article highlights the multiple uses of generalised multi-regional input–output models for carbon footprinting and concludes by highlighting important avenues for future research.

Abstract The mitigation scenarios database of the Intergovernmental Panel on Climate Change’s Sixth Assessment Report is an important resource for informing policymaking on energy transitions. However, there is a large variety of models, scenario designs, and resulting outputs. Here we analyse the scenarios consistent with limiting warming to 2 °C or below regarding the speed, trajectory, and feasibility of different fossil fuel reduction pathways. In scenarios limiting warming to 1.5 °C with no or limited overshoot, global coal, oil, and natural gas supply (intended for all uses) decline on average by 95%, 62%, and 42%, respectively, from 2020 to 2050, but the long-term role of gas is highly variable. Higher-gas pathways are enabled by higher carbon capture and storage (CCS) and carbon dioxide removal (CDR), but are likely associated with inadequate model representation of regional CO 2 storage capacity and technology adoption, diffusion, and path-dependencies. If CDR is constrained by limits derived from expert consensus, the respective modelled coal, oil, and gas reductions become 99%, 70%, and 84%. Our findings suggest the need to adopt unambiguous near- and long-term reduction benchmarks in coal, oil, and gas production and use alongside other climate mitigation targets.

The integrated assessment models (IAMs) that economists use to analyze the expected costs and benefits of climate policies frequently suggest that the “optimal” policy is to go slowly and to do relatively little in the near term to reduce greenhouse gas emissions. We trace this finding to the contestable assumptions and limitations of IAMs. For example, they typically discount future impacts from climate change at relatively high rates. This practice may be appropriate for short-term financial decisions but its extension to intergenerational environmental issues rests on several empirically and philosophically controversial hypotheses. IAMs also assign monetary values to the benefits of climate mitigation on the basis of incomplete information and sometimes speculative judgments concerning the monetary worth of human lives and ecosystems, while downplaying scientific uncertainty about the extent of expected damages. In addition, IAMs may exaggerate mitigation costs by failing to reflect the socially determined, path-dependent nature of technical change and ignoring the potential savings from reduced energy utilization and other opportunities for innovation. A better approach to climate policy, drawing on recent research on the economics of uncertainty, would reframe the problem as buying insurance against catastrophic, low-probability events. Policy decisions should be based on a judgment concerning the maximum tolerable increase in temperature and/or carbon dioxide levels given the state of scientific understanding. The appropriate role for economists would then be to determine the least-cost global strategy to achieve that target. While this remains a demanding and complex problem, it is far more tractable and epistemically defensible than the cost-benefit comparisons attempted by most IAMs.

An extensive literature documents relations between reservoir storage capacity and water supply yield and the properties of instream flow needed to support downstream aquatic ecosystems. However, the literature that evaluates the impact of reservoir operating rules on instream flow properties is limited to a few site‐specific studies, and as a result, few general conclusions can be drawn to date. This study adapts the existing generalized water evaluation and planning model (WEAP) to enable general explorations of relations between reservoir storage, instream flow, and water supply yield for a wide class of reservoirs and operating rules. Generalized relationships among these variables document the types of instream flow policies that when combined with drought management strategies, are likely to provide compromise solutions to the ecological and human negotiations for water for different sized reservoir systems. The concept of a seasonal ecodeficit/ecosurplus is introduced for evaluating the impact of reservoir regulation on ecological flow regimes.

The technical debt metaphor is widely used to encapsulate numerous software quality problems. The metaphor is attractive to practitioners as it communicates to both technical and nontechnical audiences that if quality problems are not addressed, things may get worse. However, it is unclear whether there are practices that move this metaphor beyond a mere communication mechanism. Existing studies of technical debt have largely focused on code metrics and small surveys of developers. In this paper, we report on our survey of 1,831 participants, primarily software engineers and architects working in long-lived, software-intensive projects from three large organizations, and follow-up interviews of seven software engineers. We analyzed our data using both nonparametric statistics and qualitative text analysis. We found that architectural decisions are the most important source of technical debt. Furthermore, while respondents believe the metaphor is itself important for communication, existing tools are not currently helpful in managing the details. We use our results to motivate a technical debt timeline to focus management and tooling approaches.

Septic systems serve approximately 25% of U.S. households and may be an important source of estrogenic and other organic wastewater contaminants (OWC) to groundwater. We monitored several estrogenic OWC, including nonylphenol (NP), nonylphenol mono- and diethoxycarboxylates (NP1EC and NP2EC), the steroid hormones 17beta-estradiol (E2), estrone (E1) and their glucuronide and sulfate conjugates, and other OWC such as methylene blue active substances (MBAS), caffeine and its degradation product paraxanthine, and two fluorescent whitening agents in a residential septic system and in downgradient groundwater. E1 and E2 were present predominantly as free estrogens in groundwater, and near-source groundwater concentrations of all OWC were highest in the suboxic to anoxic portion of the wastewater plume, where concentrations of most OWC were similar to those observed in the septic tank on the same day. NP and NP2EC were up to 6- to 30-fold higher, and caffeine and paraxanthine were each 60-fold lower than septic tank concentrations, suggesting net production and removal, respectively, of these constituents. At the most shallow, oxic depth, concentrations of all OWC except for NP2EC were substantially lower than in the tank and in deeper wells. Yet boron, specific conductance, and the sum of nitrate-and ammonia-nitrogen were highest at this shallow depth, suggesting preferential losses of OWC along the more oxic flow lines. As far as 6.0 m downgradient, concentrations of many OWC were within a factor of 2 of near-source concentrations. The results suggest that there is the potential for migration of these OWC, which are unregulated and not routinely monitored, in groundwater.

The term ‘carbon lock-in’ refers to the tendency for certain carbon-intensive technological systems to persist over time, ‘locking out’ lower-carbon alternatives, and owing to a combination of linked technical, economic, and institutional factors. These technologies may be costly to build, but relatively inexpensive to operate and, over time, they reinforce political, market, and social factors that make it difficult to move away from, or ‘unlock’ them. As a result, by investing in assets prone to lock-in, planners and investors restrict future flexibility and increase the costs of achieving agreed climate protection goals. Here, we develop a straight-forward approach to assess the speed, strength, and scale of carbon lock-in for major energy-consuming assets in the power, buildings, industry, and transport sectors. We pilot the approach at the global level, finding that carbon lock-in is greatest, globally, for coal power plants, gas power plants, and oil-based vehicles. The approach can be readily applied at the national or regional scale, and may be of particular relevance to policymakers interested in enhancing flexibility in their jurisdictions for deeper emissions cuts in the future, and therefore in limiting the future costs associated with ‘stranded assets’.

Abstract Potential conflicts arising from competing demands of complex water resource systems require a holistic approach to address the tradeoff landscape inherent in freshwater ecosystem service evaluation. The Water Evaluation and Planning model version 21 (WEAP21) is a comprehensive integrated water resource management (IWRM) model that can aid in the evaluation of ecosystem services by integrating natural watershed processes with socio-economic elements that include the infrastructure and institutions that govern the allocation of available freshwater supplies. The bio-physical and socioeconomic components of Battle Creek and Cow Creek, two tributaries of the Sacramento River of Northern California, USA, were used to illustrate how a new hydrologic sub-module in WEAP21 can be used in conjunction with an imbedded water allocation algorithm to simulate the hydrologic response of the watersheds and aid in evaluating freshwater ecosystem service tradeoffs under alternative scenarios. Keywords: integrated watershed managementecosystem servicessalmon restorationirrigationhydropower

Good climate policy requires the best possible understanding of how climatic change will impact on human lives and livelihoods in both industrialized and developing counties. Our review of recent contributions to the climate-economics literature assesses 30 existing integrated assessment models in four key areas: the connection between model structure and the type of results produced; uncertainty in climate outcomes and projection of future damages; equity across time and space; and abatement costs and the endogeneity of technological change. Differences in treatment of these issues are substantial and directly affect model results and their implied policy prescriptions. Much can be learned about climate economics and modelling technique from the best practices in these areas; there is unfortunately no existing model that incorporates the best practices on all or most of the questions we examine.

Equity issues have long been debated within international climate politics, focused on fairly distributing reductions in territorial emissions and fossil fuel consumption. There is a growing recognition among scholars and policymakers that curbing fossil fuel supply (as well as demand) can be a valuable part of the climate policy toolbox; this raises the question of where and how the tool should be applied. This paper explores how to equitably manage the social dimensions of a rapid transition away from fossil fuel extraction. Fossil fuel extraction leads to benefits for some people (such as extraction workers) and harms for others (such as pollution-affected communities). A transition must respect and uphold the rights of both groups, while also staying within climate limits, as climate impacts will fall most heavily on the world’s poor. This paper begins by reviewing how extraction affects economies and communities and the different transitional challenges they face. Based on that review, it then examines three common equity approaches – economic efficiency, meeting development needs, and effort-sharing. Drawing lessons from the strengths and weaknesses of these approaches, the paper proposes five principles as a basis for equitably curbing fossil fuel extraction within climate limits:(1) Phase out global extraction at pace consistent with limiting warming to 1.5°C;(2) Enable a just transition for workers and communities;(3) Curb extraction consistent with environmental justice;(4) Reduce extraction fastest where doing so will have the least social costs;(5) Share transition costs fairly, according to ability to bear those costs.Key policy insights:Fossil fuel extraction is unlikely to be a viable path to development because the Paris Agreement goals require most fossil fuel use to be ended within a generation;Extraction should be phased out fastest in diversified, wealthier economies that can better absorb the transitional impacts;Governments of extracting countries should enact ambitious industrial policy to diversify their economies, alongside economic and employment policies to enable a just transition;The costs of a just transition should be borne by those most able to bear it: poorer countries can reasonably demand financial support.

The Paris Agreement establishes provisions for using international carbon market mechanisms to achieve climate mitigation contributions. Environmental integrity is a key principle for using such mechanisms under the Agreement. This paper systematically identifies and categorizes issues and options to achieve environmental integrity, including how it could be defined, what influences it, and what approaches could mitigate environmental integrity risks. Here, environmental integrity is assumed to be ensured if the engagement in international transfers of carbon market units leads to the same or lower aggregated global emissions. Four factors are identified that influence environmental integrity: the accounting for international transfers; the quality of units generated, i.e. whether the mechanism ensures that the issuance or transfer of units leads to emission reductions in the transferring country; the ambition and scope of the mitigation target of the transferring country; and incentives or disincentives for future mitigation action, such as possible disincentives for transferring countries to define future mitigation targets less ambitiously or more narrowly in order to sell more units. It is recommended that policy-makers combine several approaches to address the significant risks to environmental integrity.Key policy insights Robust accounting is a key prerequisite for ensuring environmental integrity. The diversity of nationally determined contributions is an important challenge, in particular for avoiding double counting and for ensuring that the accounting for international transfers is representative for the mitigation efforts by Parties over time.Unit quality can, in theory, be ensured through appropriate design of carbon market mechanisms; in practice, existing mechanisms face considerable challenges in ensuring unit quality. Unit quality could be promoted through guidance under Paris Agreement Article 6, and reporting and review under Article 13.The ambition and scope of mitigation targets is key for the incentive for transferring countries to ensure unit quality because countries with ambitious and economy-wide targets would have to compensate for any transfer of units that lack quality. Encouraging countries to adopt ambitious and economy-wide NDC targets would therefore facilitate achieving environmental integrity.Restricting transfers in instances of high environmental integrity risk – through eligibility criteria or limits – could complement these approaches.

Self-adaptive systems tend to be reactive and myopic, adapting in response to changes without anticipating what the subsequent adaptation needs will be. Adapting reactively can result in inefficiencies due to the system performing a suboptimal sequence of adaptations. Furthermore, when adaptations have latency, and take some time to produce their effect, they have to be started with sufficient lead time so that they complete by the time their effect is needed. Proactive latency-aware adaptation addresses these issues by making adaptation decisions with a look-ahead horizon and taking adaptation latency into account. In this paper we present an approach for proactive latency-aware adaptation under uncertainty that uses probabilistic model checking for adaptation decisions. The key idea is to use a formal model of the adaptive system in which the adaptation decision is left underspecified through nondeterminism, and have the model checker resolve the nondeterministic choices so that the accumulated utility over the horizon is maximized. The adaptation decision is optimal over the horizon, and takes into account the inherent uncertainty of the environment predictions needed for looking ahead. Our results show that the decision based on a look-ahead horizon, and the factoring of both tactic latency and environment uncertainty, considerably improve the effectiveness of adaptation decisions.

Communities in many parts of the world, especially in developing countries, face obstacles in supplying continuous water to household consumers. Authorities often cite water scarcity as the cause, but we demonstrate that environmental constraints constitute only one aspect of a multi-dimensional problem. By asking what causes intermittent domestic water supply, this literature review (129 articles) identifies 47 conditions of intermittent systems and the causal-consequential pathways between them that can reinforce intermittency. These pathways span several disciplines including engineering, government administration and anthropology, and when viewed together they (1) emphasize the human drivers of intermittency; (2) suggest generalized interventions; and (3) reveal a gap in the literature in terms of meaningful categorizations of the reliability of intermittent supplies. Based on the reliability of consumers’ water access, we propose three categories of intermittency—predictable, irregular, and unreliable—to facilitate comparisons between case studies and transfers of solutions.

Traditional biomass remains the dominant contributor to the energy supply of a large number of developing countries, where it serves the household energy needs of over a third of humanity in traditional cookstoves or open fires. Efforts to reduce the enormous human health, socioeconomic, and environmental impacts by shifting to cleaner cookstoves and cleaner biomass-derived fuels have had some success, but much more needs to be done, possibly including the expanded use of fossil-derived fuels. Concurrently, biomass is rapidly expanding as a commercial energy source, especially for transport fuels. Bioenergy can positively contribute to climate goals and rural livelihoods; however, if not implemented carefully, it could exacerbate degradation of land, water bodies, and ecosystems; reduce food security; and increase greenhouse gas (GHG) emissions. For large-scale commercial biofuels to contribute to sustainable development will require agriculturally sustainable methods and markets that provide enhanced livelihood opportunities and equitable terms of trade. The challenge lies in translating the opportunity into reality.

Abstract: Using the latest available General Circulation Model (GCM) results we present an assessment of climate change impacts on California hydrology and water resources. The approach considers the output of two GCMs, the PCM and the HadCM3, run under two different greenhouse gas (GHG) emission scenarios: the high emission A1fi and the low emission B1. The GCM output was statistically downscaled and used in the Variable Infiltration Capacity (VIC) macroscale distributed hydrologic model to derive inflows to major reservoirs in the California Central Valley. Historical inflows used as inputs to the water resources model CalSim II were modified to represent the climate change perturbed conditions for water supply deliveries, reliability, reservoir storage and changes to variables of environmental concern. Our results show greater negative impacts to California hydrology and water resources than previous assessments of climate change impacts in the region. These impacts, which translate into smaller streamflows, lower reservoir storage and decreased water supply deliveries and reliability, will be especially pronounced later in the 21st Century and south of the San Francisco bay Delta. The importance of considering how climate change impacts vary for different temporal, spatial, and institutional conditions in addition to the average impacts is also demonstrated.

Importance: Limited literature has characterized patterns of mental illnesses and barriers in seeking mental health care among police officers. Objectives: To assess the prevalence of mental illness (diagnosis) and symptoms of mental illness, evaluate the characteristics of officers interested in seeking mental health care, and characterize perceptions of mental health care use. Design, Setting, and Participants: This survey study was conducted among officers at a large police department in Dallas-Fort Worth, Texas. Focus group sessions were conducted from April 1, 2019, to November 30, 2019, and the survey was conducted from January 1 to February 27, 2020. A total of 446 sworn, employed patrol officers who were present during the recruitment briefing were eligible to participate in surveys and focus groups. Main Outcomes and Measures: Officers reported lifetime or current diagnosis of depression, anxiety, and posttraumatic stress disorder, as well as current mental health symptoms (using validated screeners of depression, anxiety, posttraumatic stress disorder, and suicidal ideation or self-harm) and mental health care use in the past 12 months. Focus group data were collected to contextualize mental health care use. Logistic regression analyses were used for quantitative data, and focus groups were iteratively coded by 4 coders using inductive and deductive thematic identification. Results: Of the 446 officers invited to participate, 434 (97%) completed the survey (mean [SD] age, 37 [10] years; 354 [82%] male; 217 White [50%]). Of these officers, 19 (17%) had sought mental health care services in the past 12 months. A total of 54 officers (12%) reported a lifetime mental health diagnosis, and 114 (26%) had positive screening results for current mental illness symptoms. Among officers with positive screening results, the odds of interest in using mental health services was significantly higher for officers with suicidal ideation or self-harm than for those who did not (adjusted odds ratio, 7.66; 95% CI, 1.70-34.48). Five focus groups were conducted with 18 officers and found 4 primary barriers in accessing mental health services: (1) inability to identify when they are experiencing a mental illness, (2) concerns about confidentiality, (3) belief that psychologists cannot relate to their occupation, and (4) stigma that officers who seek mental health services are not fit for duty. Conclusions and Relevance: The study found that although few officers were seeking treatment, they were interested in seeking help, particularly those with suicidal ideation or self-harm. Additional interventions appear to be needed to systematically identify and refer officers to health care services while mitigating their concerns, such as fear of confidentiality breach.

Abstract Urban air pollution is high on global health and sustainability agendas, but information is limited on associated city-level disease burdens. We estimated fine particulate matter (PM 2.5 ) mortality in the 250 most populous cities worldwide using PM 2.5 concentrations, population, disease rates, and concentration-response relationships from the Global Burden of Disease 2016 Study. Only 8% of these cities had population-weighted mean concentrations below the World Health Organization guideline for annual average PM 2.5 . City-level PM 2.5 -attributable mortality rates ranged from 13–125 deaths per 100,000 people. PM 2.5 mortality rates and carbon dioxide (CO 2 ) emission rates were weakly positively correlated, with regional influences apparent from clustering of cities within each region. Across 82 cities globally, PM 2.5 concentrations and mortality rates were negatively associated with city gross domestic product (GDP) per capita, but we found no relationship between GDP per capita and CO 2 emissions rates. While results provide only a cross-sectional snapshot of cities worldwide, they point to opportunities for cities to realize climate, air quality, and health co-benefits through low-carbon development. Future work should examine drivers of the relationships (e.g. development stage, fuel mix for electricity generation and transportation, sector-specific PM 2.5 and CO 2 emissions) uncovered here and explore uncertainties to test the robustness of our conclusions.