Climate Change Mitigation Goals Research Articles

The climate change mitigation potential of annual grasslands under future climates.

Composted manure and green waste amendments have been shown to increase net carbon (C) sequestration in rangeland soils and have been proposed as a means to help lower atmospheric CO2 concentrations. However, the effect of climate change on soil organic C (SOC) stocks and greenhouse gas emissions in rangelands is not well understood, and the viability of climate change mitigation strategies under future conditions is even less certain. We used a process-based biogeochemical model (DayCent) at a daily time step to explore the long-term effects of potential future climate changes on C and greenhouse gas dynamics in annual grassland ecosystems. We then used the model to explore how the same ecosystems might respond to climate change following compost amendments to soils and determined the long-term viability of net SOC sequestration under changing climates. We simulated net primary productivity (NPP), SOC, and greenhouse gas fluxes across seven California annual grasslands with and without compost amendments. We drove the DayCent simulations with field data and with site-specific daily climate data from two Earth system models (CanESM2 and HadGEM-ES) and two representative concentration pathways (RCP4.5 and RCP8.5) through 2100. NPP and SOC stocks in unamended and amended ecosystems were surprisingly insensitive to projected climate changes. A one-time amendment of compost to rangeland acted as a slow-release organic fertilizer and increased NPP by up to 390-814 kg C ha-1 year-1 across sites. The amendment effect on NPP was not sensitive to Earth system model or emissions scenario and endured through the end of the century. Net SOC sequestration amounted to 1.96 ± 0.02 Mg C ha-1 relative to unamended soils at the maximum amendment effect. Averaged across sites and scenarios, SOC sequestration peaked 22 ± 1 years after amendment and declined but remained positive throughout the century. Though compost stimulated nitrous oxide (N2 O) emissions, the cumulative net emissions (in CO2 equivalents) due to compost were far less than the amount of SOC sequestered. Compost amendments resulted in a net climate benefit of 69.6 ± 0.5 Tg CO2 e 20 ± 1 years after amendment if applied to similar ecosystems across the state, amounting to 39% of California's rangeland. These results suggest that the biogeochemical benefits of a single amendment of compost to rangelands in California are insensitive to climate change and could contribute to decadal-scale climate change mitigation goals alongside emissions reductions.

Decarbonisation of industrial clusters: A place-based research agenda

Decarbonisation of industrial clusters is crucial for climate change mitigation and net zero policy goals, involving the deployment of technologies including hydrogen and carbon capture, utilisation and storage. Industrial clusters co-locate large-scale facilities for electricity generation and distribution, oil refineries and the manufacturing and distribution of products including fertilisers, glass, plastics and aerosols. Given the geographical, co-located rationale of industrial clusters, this perspective argues that adopting a place-based approach is fundamental to the success of industrial decarbonisation. The place-based approach offers two significant advantages. First, it provides conceptual and methodological tools to guide industrial decarbonisation in ways that are grounded in the social sciences. Second, it can assist with joining up diverse policy goals - mitigating climate change, enabling economic prosperity and reducing regional inequalities. Three conceptual pillars of this approach are identified - ontology, place-making and sense of place. An illustrative case study draws on this approach to critically assess the emergence of the concept of ‘SuperPlaces’ in UK policy discourse. The article concludes by proposing a research agenda that can inform policy making and practice in ways that go beyond a superficial or ephemeral appropriation of place. In doing so, this agenda can enable emissions reduction in ways that are considered fair and acceptable by local communities.

Nature-Based Solutions in Coastal and Estuarine Areas of Europe

Momentum for sustainable and climate resilience solutions for coastal protection are growing globally given the pressing need to prevent further loss of biodiversity and ecosystems while meeting the climate change adaptation and mitigation goals. Nature-Based Solutions (NbS) represent an opportunity to align environmental and resilience goals, at a time of strained budgets in a global context and when short-term needs may run counter to long-term goals. In Europe, NbS fit the mandates of major EU environmental and climate change policies by restoring biodiversity and enhancing climate-resilience and carbon sequestration. Previous studies have compiled scientific evidence about hydro-meteorological hazards for the use of NbS. However, their implementation at scale is still lacking. As the knowledge and experience with NbS for adaptation to natural hazards and climate change increases, it becomes more important to draw lessons learned and insights for replicating and scaling up NbS, especially in coastal areas where their implementation is still limited compared to other environments. This study analyzed NbS case studies across European coastal and estuarine areas to draw key lessons, understand better the current status of implementation, and identify key challenges and gaps. From a total of 59 NbS case studies associated with flooding, erosion and biodiversity loss, results show an increase in NbS implementation since 1990s, but most rapidly between 2005 and 2015. Most of the case studies are hybrid solutions employing wetlands, predominantly located in the United Kingdom (UK) and the Netherlands. Funding of NbS is largely from public sources, and rarely come from a single or a private source. Three-quarters of the case studies reported monitoring activities, but more than half did not disclose quantitative results related to effectiveness against flooding and/or erosion. The need to improve coastal defenses was indicated as the main motivation for NbS implementation over traditional structures, while sustainability was the most mentioned additional reason. Although a variety of co-benefits and lessons learned was identified, clearer descriptions and enhanced details of such information are required. There is a need for tools and strategies to expand knowledge sharing of lessons learned to enable further replication of successful cases in other areas.

Climate change mitigation of drop-in biofuels for deep-sea shipping under a prospective life-cycle assessment

The shipping sector is seeking options to reduce its emissions of greenhouse gases (GHGs) and achieve ambitious climate change mitigation goals. Unlike short-sea shipping that can rely on electrification of coastal vessels, drop-in biofuels are among the most promising options for deep-sea shipping decarbonization. However, environmental sustainability analyses of marine biofuels are limited, and usually do not include the influence of future changes in the background energy system nor the climatic effects of near-term climate forcers (NTCFs). In our study, we assess the climate change mitigation potential of various marine biofuels produced from forest residues in Norway (a country with ambitious plans for emission reduction from shipping) using a prospective life-cycle assessment (LCA) where the projected trends in the energy and transport sectors are integrated with improvements in the biofuel value chain for the next decades (2030–2050). Relative to fossil-based alternatives, climate mitigation potentials of biofuels range from 65% to 85% with short-term (GWP20) and to 78%–87% with long-term (GTP100) climate impacts. The inclusion of NTCFs reduces the mitigation benefits of biofuels in the short term, while it slightly increases them in the long term. The explicit modeling of technology and socio-economic changes under future policy scenarios indicates a reduction in the climate impacts of biofuels by up to 54% in 2050 when compared to the current situation. The amount of residues potentially available in Norway is sufficient to meet the present demand for liquid fuels in deep-sea shipping, thus providing yearly climate mitigation of 0.9–1.1 million tons of CO2-eq (equal to 6–7% of today's climate impacts from the entire transport sector in the country). Our analysis shows the large climate change mitigation potential of drop-in biofuels, and it provides new quantitative estimates that can help guiding a sustainability shift in the deep-sea shipping sector.

Shifting Trade-offs: Finding the Sustainable Nexus of Hydropower and Environmental Flows in the San Joaquin River Watershed, California

Environmental flow management in watersheds with multi-objective reservoirs is often presented as an additional constraint to an already strained and over-allocated stream system. Nevertheless, environmental flow legislation and regulatory policies are increasingly being developed and implemented globally. In California, USA, recent legislative and regulatory policies place environmental flows at the forefront of the state’s water management objectives; however, the increased reliance on hydropower to support climate change mitigation goals may complicate efforts on both issues. This study modelled alternative environmental flow strategies in the major tributaries to the San Joaquin River in California. Strategies included detailed water management rules for hydropower production, flood control, and water deliveries, and three methodological approaches to environmental flow releases: minimum instream flows (“baseline”) year-round, 40% of full natural flow (FNF) during the spring runoff season and minimum releases the remainder of the year, and functional flows year-round. Results show that environmental flow strategies affect downstream flow releases in each of the San Joaquin’s four sub-basins differently depending on infrastructure capacity, water management objectives, and hydrologic year types. While hydropower production was comparable or declined in the Stanislaus, Tuolumne, and Merced basins, functional flow and 40% FNF strategies increased hydropower production in the Upper San Joaquin basin by 11%. Uncontrolled spill of high flow events decreased when high flow releases were based on hydrologic cues rather than exclusively on flood storage capacity. Water deliveries were reduced in all years regardless of environmental flow strategy. The 40% FNF and functional flow strategies both increased water released to the river relative to baseline, but in different ways. The functional flow strategy allocated water in a holistic approach that enhanced ecological functions in all years, but particularly in moderate and wet years. In contrast, the 40% FNF strategy provided increased flows relative to baseline and some ecological benefit in dry years, but less ecological benefit in other years. This study shows that alternative environmental flow strategies will have different and important trade-offs for integrated water management, and may mutually benefit seemingly conflicting objectives.

Clean Transport Network in Nigerian Environment: Climatic Issues and Way Forward

There is dire need for adequate planning and digital innovations for developing clean transport networks in African urban communities for better climatic condition and sustainable green environment. This paper examines climatic actions and sustainability perspectives of clean transport network development in Nigeria. Methodology adopted included reconnaissance survey of transport facilities, literature survey, checking of available data and government policy on clean transport network in Nigeria. Other information was also obtained from interview of selected engineers and energy experts in transportation sectors. Finding revealed that there is need to improve on financial capacities and future investments in digital advancements for integrated solutions in infrastructural development, resilient communities and transportation facilities for environmental health and clean transport network. The transportation industry is crucial to meet climate change mitigation goals and the Sustainable Development Goals (SDGs). Because of the expanding demand for transportation from various economic sectors such as industry, energy, health, home, and commercial and other aspects, the demand for transportation is in increasing trend. All issues related to road construction, Public Private Partnerships, traffic management and contract adjudication in transport sector must be carefully resolved. The paper concluded that there is urgent need to strengthen the development of clean transport network in Nigerian environment especially on climate action and sustainability perspectives. The impact of sustainable applications of mobility cannot be over emphasized. Adequate engineering and sustainable green initiatives should be deployed for economic growth and clean transport network in Nigeria.

Premature Deaths in Africa Due To Particulate Matter Under High and Low Warming Scenarios.

Sustainable development and climate change mitigation can provide enormous public health benefits via improved air quality, especially in polluted areas. We use the latest state‐of‐the‐art composition‐climate model simulations to contrast human exposure to fine particulate matter in Africa under a “baseline” scenario with high material consumption, population growth, and warming to that projected under a sustainability scenario with lower consumption, population growth, and warming. Evaluating the mortality impacts of these exposures, we find that under the low warming scenario annual premature deaths due to PM2.5 are reduced by roughly 515,000 by 2050 relative to the high warming scenario (100,000, 175,000, 55,000, 140,000, and 45,000 in Northern, West, Central, East, and Southern Africa, respectively). This reduction rises to ∼800,000 by the 2090s, though by that time much of the difference is attributable to the projected differences in population. By contrast, during the first half of the century benefits are driven predominantly by emissions changes. Depending on the region, we find large intermodel spreads of ∼25%–50% in projected future exposures owing to different physics across the ensemble of 6 global models. The spread of projected deaths attributable to exposure to fine particulate matter, including uncertainty in the exposure‐response function, are reduced in every region to ∼20%–35% by the non‐linear exposure‐response function. Differences between the scenarios have an even narrower spread of ∼5%–25% and are highly statistically significant in all regions for all models. These results provide valuable information for policy‐makers to consider when working toward climate change mitigation and sustainable development goals.

Community forestry in Cameroon: opportunity or constraint for REDD+?

PurposeThis study aims to identify opportunities and constraints of community forestry in the context of forest decentralization in Cameroon and what can be capitalized on for sound REDD+ design and implementation.Design/methodology/approachA qualitative approach to data collection was used through content analysis of 1994 forestry law, reports and publications related to decentralized forest management, community forestry and REDD+ in Cameroon. Principles that govern community forest and REDD+ were highlighted and opportunities and constraints of community forestry for REDD+ projects were discussed.FindingsCommunity forestry was developed principally to protect forests in order to support the subsistence and income-generating extractive activities of forest-dependent communities. Community forestry governance arrangements were not designed with the objective of achieving verifiable emissions reductions or carbon stock values. Hence, existing community forestry institutions may not address all the specific demands of REDD+ programs. However, existing community institutions and practices can be strengthened or modified to align better with climate change mitigation goals and to achieve REDD+ objectives in community forestry sites. On the other hand, REDD+ was developed principally to mitigate climate change by reducing emissions from deforestation and forest degradation principally within developing countries where the livelihoods of forest-dependent people are a central component of all forest management policies. However, despite fundamental differences between community forestry and REDD+, there is substantial synergy between their objectives, and the dual forest conservation and livelihood development focus of both programs means that policies that strengthen and support existing community forestry institutions and sites will advance REDD+ objectives. As such, REDD+ will likely to be more successful if it builds on lessons learned from community forestry.Originality/valueThis paper demonstrates how REDD+ is more likely to succeed if it builds on the lessons learned from community forestry over the past 20-plus years in Cameroon. It also discusses how REDD+ can benefit from community forestry and how some of the many challenges related to community forestry can be directly addressed by the REDD+ mechanism. Further, this paper also argues how the congruence between community forestry and REDD+ can effectively facilitate the direct use of community forestry as a tool to achieve REDD+ goals.

Filter Cake Removal during the Cementing and Completion Stages in CO2 Storage Wells: Current Developments, Challenges, and Prospects

Carbon capture and storage (CCS) technology has become one of the most cost‐effective and promising ways to achieve global climate change mitigation goals. The CO2 storage capacity in depleted oil and gas reservoirs is currently the safest and most economical option. The long‐term sealing of the cement–formation interface in CO2 storage wells (CSW) is essential to avoid CO2 leakage. The filter cake easily affects the interfacial sealing ability, which is a thin impermeable layer formed by drilling fluid residue or solid particles remaining on the borehole wall due to permeable formation. Filter cake removal is essential for favorable cementation and production efficiency. This study highlights the current developments and the main challenges for oil‐ and water‐based mud filter cake removal during the cementing and completion process. Moreover, research ideas and recommendations for various types of filter cake removal are proposed to provide a reference for future work. This information helps deepen understanding with respect to the different filter cake removal options available in the CCS industry and provides a knowledge base that can facilitate the improvement of the cementing quality and production efficiency of existing systems to combat battle CSW safety and production efficiency problems.

Modeling and Evaluation of Market Incentives for Battery Electric Vehicles

Electric mobility has great potential to help achieve global climate change mitigation goals. Within the domain of electric vehicles (EVs), battery electric vehicles (BEVs) have the largest advantage over conventional internal combustion engine technology. However, their penetration depends on many factors. Several studies have investigated the different policy incentives supporting the EV market, but less analytical research has been conducted to evaluate the different incentives. This study investigates the wide range of incentives that were adopted across 15 countries between 2010 and 2018, and their effectiveness in the market amidst other factors, using a generalized linear model. The results of the statistical analysis identified the availability of local BEV production facility, income, accessibility to fast charging infrastructure, and value-added tax exemptions as positive and statistically significant factors to the market share of BEVs across the years, while positive significant correlations were not identified for the other factors and incentives investigated. This emphasizes the impact of economic performance, technological certainty, and the presence of charging infrastructure with fast charging solutions in BEV adoption decision making, and could be an indication to policymakers of the limited impact of other factors when considered over a length of time.

Quantifying the effectiveness and health co-benefits of climate change mitigation actions across sectors: a protocol for an umbrella review

Background: Effective and rapid actions are required to achieve global goals for climate change mitigation, and there is an opportunity to ensure that the actions taken are also positive for human health. However, little is known about the relative magnitude of the health co-benefits that can be achieved from mitigation actions, so robust and comprehensive syntheses of the evidence on the nature and effects of relevant actions are required. This paper presents a protocol for an interdisciplinary and cross-sectoral umbrella review of systematic reviews, synthesising modelled and empirical evidence on such actions. Methods: Nine bibliographic databases will be searched, capturing literature across a wide range of disciplines and sectors. Unique records retrieved by the searches will be screened by two independent reviewers. The quality of all the included systematic reviews will be assessed using A MeaSurement Tool to Assess Systematic Reviews (AMSTAR) 2 critical appraisal tool. Data will be extracted on methodological and thematic characteristics of the reviews, nature of the actions, and their effects on greenhouse gas emission reduction, health, and its determinants, as well as any other reported effects and interactions across different actions. Results: Narrative and quantitative synthesis methods will be used to create a typology of relevant actions, map pathways to their impacts on health, compare the magnitude of health and greenhouse gas (GHG) emission reduction impacts by selected characteristics of the actions and the nature of the evidence, as well as to identify gaps in evidence syntheses. Conclusion: This review will identify the most effective actions for global climate change mitigation and health based on the best available scientific evidence. This protocol has been registered in PROSPERO, Reg No.: CRD42021239292.

Energy transition in the UKCS – Modelling the effects of carbon emission charges on upstream petroleum operations

The UK has ambitious decarbonisation, climate change mitigation and energy transition goals. The upstream petroleum sector in the UK shares in these goals, as evidenced by its North Sea Transition Deal and as set out in its sector ‘Roadmap 2035’ for emissions reduction. Participation in an emissions trading scheme as a mechanism for achieving these goals is a key strategy identified in the sector roadmap. Currently, only qualifying installations in the UK Continental Shelf (UKCS) are charged for their emissions. Notwithstanding, prudent non-qualifying operators are also now incorporating these charges in their financial models for asset valuation purposes. This paper uses a recently updated database of 21 new UKCS fields to examine the effects of carbon emission charges on upstream petroleum operations in the province. We find that emission charges increase operating expenditures, which results (1) an acceleration of the timing of the economic limit of fields, leading to significantly lower petroleum production and carbon emissions; and (2) a reduction in the economic value of petroleum fields hence diminishing the competitiveness of the UKCS. These outcomes advance the energy transition cause of the UK. However, they give rise to major implications for the UK, including energy security, jobs, risk of exposure to a carbon leakage situation, and so on. We advocate a ‘just transition’ approach to energy transition, where petroleum production in the UKCS progresses but with a carbon footprint that is reduced and consistent with an economic optimum.

Challenges in the Governance of Community-Managed Forests in Ethiopia: Review

A large proportion of the rural population in Ethiopia depends on community-managed forests for food security and livelihoods. However, the government and development partners have paid little attention to the governance challenges which limit the contributions of community-managed forests to food security and livelihoods. Also lacking is a synthesis of evidence relating to the requirements for improved governance to support the efforts of decision makers and practitioners. This paper attempts to review and synthesize the available evidence with the aim of identifying the requirements to achieve improved governance in community-managed forests. The results revealed that failure to devise benefit-sharing mechanisms which consider the heterogeneity of rural communities was prevalent. Interference of local authorities and elite capture in decision-making processes of forest and landscape restoration also compromised the willingness of rural communities to engage in collective action. Requirements such as the identification of the needs of specific categories of communities and enabling of the negotiation of diverse interests in the design and implementation of interventions could improve the governance of community-managed forests. Developing management plans and business model scenarios which balance the ecological and socio-economic goals at a local level in collaboration with rural communities is important to improve the governance of community-managed forests. There is also a need to revisit the practice of evaluating the performance of community-managed forests almost exclusively based on the goals of climate change adaptation and mitigation and biodiversity conservation.

Steam and Pressure Management for the Conversion of Steelworks Arising Gases to H2 with CO2 Capture by Stepwise Technology

Steel production is a main source of CO2 emissions globally. These emissions must be drastically reduced to meet climate change mitigation goals. STEPWISE is a Sorption Enhanced Reactive Process (SERP) technology that converts steel works arising gases to H2 with simultaneous CO2 capture. The main energy requirements of the process are the high- and low-pressure steam quantities that are needed to rinse and regenerate the adsorbent. In this simulation study, the separation performance of STEPWISE is evaluated over a range of steam and feed pressure inputs by searching those design points where CO2 recovery and purity percentages are equalized. This method is used to facilitate the comparison of different operating regimes. Results highlight the importance of the rinse to purge ratio (R/P) as a design variable. A higher R/P ratio is demonstrated to maintain CO2 recovery and purity of ~95.5%, while total steam consumption and feed carbon loading are reduced by 27% and 20%, respectively. This is achieved without changing other parameters, like cycle time. Additionally, it is demonstrated that the CO2 capture performance can be maintained for varying feed pressure values by tuning the feed carbon loading. Future studies are recommended to focus on the expected role of the feed gas steam content on these findings.

Deforestation scenarios show the importance of secondary forest for meeting Panama\u2019s carbon goals

ContextTropical forest loss has a major impact on climate change. Secondary forest growth has potential to mitigate these impacts, but uncertainty regarding future land use, remote sensing limitations, and carbon model accuracy have inhibited understanding the range of potential future carbon dynamics.ObjectivesWe evaluated the effects of four scenarios on carbon stocks and sequestration in a mixed-use landscape based on Recent Trends (RT), Accelerated Deforestation (AD), Grow Only (GO), and Grow Everything (GE) scenarios.MethodsWorking in central Panama, we coupled a 1-ha resolution LiDAR derived carbon map with a locally derived secondary forest carbon accumulation model. We used Dinamica EGO 4.0.5 to spatially simulate forest loss across the landscape based on recent deforestation rates. We used local studies of belowground, woody debris, and liana carbon to estimate ecosystem scale carbon fluxes.ResultsAccounting for 58.6 percent of the forest in 2020, secondary forests (< 50 years) accrue 88.9 percent of carbon in the GO scenario by 2050. RT and AD scenarios lost 36,707 and 177,035 ha of forest respectively by 2030, a carbon gain of 7.7 million Mg C (RT) and loss of 2.9 million Mg C (AD). Growing forest on all available land (GE) could achieve 56 percent of Panama’s land-based carbon sequestration goal by 2050.ConclusionsOur estimates of potential carbon storage demonstrate the important contribution of secondary forests to land-based carbon sequestration in central Panama. Protecting these forests will contribute significantly to meeting Panama’s climate change mitigation goals and enhance water security.

CLIMATE CRISIS AS A CATALYST TO ADVANCE INDIGENOUS RIGHTS

Climate change is the most grievous threat of the 21st century and disproportionately affects politically marginalised communities such as Indigenous peoples. As custodians of approximately 80% of the planet’s biodiversity, Indigenous cultures have practised sustainable management of ecosystems and resources over millennia providing vital pathways for humanity to better mitigate accelerating climate change impacts. This article argues that a rights-based approach is an important legal avenue to help better protect and advance Indigenous peoples’ rights and the biodiversity in their regions. The challenge is to develop a framework that incorporates Indigenous rights into international human rights law while obtaining judicial buy-in by domestic legal systems and nations. Drawing from international legal instruments to better protect and bolster Indigenous rights, and using Aotearoa New Zealand as a case study, this paper identifies how rights of Indigenous communities can be enhanced while serving the global goals of climate change mitigation and adaptation.

Spatio-temporal unevenness in local land system regime shifts caused by land deals in Lao PDR

Extensive land-use “regime shifts” have been observed as rapid transitions from natural land cover or subsistence-oriented land use to intensified and/or expanded commodity production. However, it is often unclear whether these land-use changes are part of broader land system regime shifts in which pre-existing production systems and livelihood strategies are fundamentally transformed along with observable land-use changes rather than simply displaced or eliminated. This is a critical social-environment question given that regime shifts are often a desired and intended outcome of national rural development and market-liberalization policies but must also be attentive to environmental conservation and/or climate change mitigation goals. We investigated whether nationally extensive land-use changes implemented through large-scale land deals in Lao People’s Democratic Republic resulted in full, partial, or no village- and landscape-level regime shifts in and around land deals. Overall, land deals triggered a wide variety of full, partial, and no regime shift outcomes. Land deals with both domestic and foreign investors produced positive and negative outcomes, although foreign land deals for the production of rubber led to significantly higher rates of indirect land-use change in impacted villages than domestic and/or non-rubber land deals. Also, financial compensation alone was insufficient to improve community well-being because it could be reinvested to perpetuate previous land uses without the desired transformation in livelihoods and rural development. Land deals that exhibited greater social embeddedness (i.e., provided adequate compensation complemented by job-creation and improved access to infrastructure and/or services) were more likely to lead to positive regime shifts. Our findings demonstrate that any land system regime shift will produce both winners and losers, and thus it becomes necessary to critically analyze the localized distribution of social and environmental costs and benefits within broader-scale land-use regime shifts.

Towards decarbonisation targets by changing setpoint temperature to avoid building overcooling and implementing district cooling in (sub)tropical high-density cities – A case study of Hong Kong

Climate warming, rapid economic development, and urbanisation in (sub)tropical regions lead to increasing electricity demand for building air-conditioning that could jeopardise the efforts of decarbonisation required to meet the climate change mitigation goals. This study investigates two strategies to reduce building energy consumption due to air-conditioning: 1) the bottom-up adoption of an Adaptive Thermal Comfort (ATC)-based cooling setpoint temperature and 2) the top-down implementation of efficient District Cooling Systems (DCS). The subtropical high-density city of Hong Kong is chosen for case study since detailed data on the city's current and realistic future urban form and function are available. Numerical simulations representing the feedback between urban climate and building energy consumption are conducted by employing a mesoscale atmospheric model coupled to an urban climate and building energy model for a scenario of future (mid-21st century) Hong Kong. A prolonged high temperature event representative of future extreme conditions is simulated, during which the ATC and DCS strategies reduce building cooling energy consumption by 9.7% and 5.9%, respectively. The ATC has almost no effect on the local meteorological conditions, whereas the DCS reduces daytime sensible heat flux by up to 600 W/m2 and near-surface air temperature by almost 1 °C in the districts where it is adopted. The DCS thus also contributes to lowering outdoor heat stress in these areas. The cost-free ATC strategy is easily applicable in residential buildings worldwide and can break the vicious cycle in overcooled buildings, where occupants are acclimatised to lower indoor temperature and thus require more air-conditioning than necessary. Apart from reducing energy consumption and near-surface air temperature, the DCS brings additional benefits in building space utilisation and rooftop design. Future policy orientations should therefore encourage a societal change towards the ATC lifestyle and incorporate DCS in the planning of new development areas.

Quantifying the asymmetric spillovers in sustainable investments

Owing to the growing importance of socially responsible investments in the wake of climate change mitigation goals, we estimate the asymmetric time- and frequency-spillovers between global sustainable investments. Additionally, we examine the influence of global risk factors such as US and UK economic policy uncertainties, stock market volatility, US treasury market volatility and infectious diseases related market volatility on the short- and long-run connectedness in these investments. To this end, we use daily returns and volatilities of 14 country-level Dow Jones Sustainability Indices from January 2005 to March 2021. By employing the asymmetric versions of Diebold & Yilmaz (2012, 2014) and Barunik & Krehlik (2018) time–frequency connectedness, our study addresses both good and bad contagion among sustainable investments that is unexplored in the recent literature. The results reveal significant time–frequency asymmetries in return spillovers across different regions in the short- and long-run. Germany, France, Netherlands, and the UK are the primary shock transmitters. We find more intra-regional connectedness among the Asian countries as opposed to inter-regional connectedness. Negative returns propagate more intensely than positive ones, and this contagion is considerably boosted during crises, including the COVID19. The VIX and COVID19 remain influential in the long run. The impact of MOVE is positive in the short-run while negative in the long-run, which shows an overreaction of connectedness to the US treasury market volatility in the short-run. Economic policy uncertainties in the US and the UK increase spillovers more intensely in the short-run. These results are robust to using volatility spillovers, the choice of rolling window and various forecast horizons. Our findings are distinctly important for socially responsible investors as we point out international portfolio diversification opportunities among sustainable investments. Understanding the dynamics of connectedness in sustainable investments can potentially boost financing in this market through portfolio choices and contribute to the climate change mitigation agenda of the United Nations.

Climate and air pollution implications of potential energy infrastructure and policy measures in India

India is a rapidly developing economy with interrelated air quality, sustainable development, and climate change mitigation goals. There are unique challenges to achieving each of these goals as well as potential tradeoffs among them. This study examines the implications of possible future energy, climate, and air pollution control policies and measures in India through 2050. We take a scenario approach using the GCAM global energy-climate-land model combined with the Hector simple climate model and the TM5-FASST air quality source-receptor model to examine energy, climate and air quality outcomes. Reducing use of traditional biomass in buildings can reduce primary carbonaceous particulate emissions well below 2015 levels. However, policies that are more ambitious than current plans would likely be required to reduce SO2 and NOx emissions well below 2015 levels. Among single policy cases considered, pricing of greenhouse gas (GHG) emissions and expansion of natural gas infrastructure have the largest impacts on overall energy system changes relative to the reference scenario. Ambitious air pollution control and GHG policies lead to the largest reductions in air pollution concentrations and radiative forcing, respectively. However, ambitious air pollution control and GHG policies differ in the extent to which they support or impede other policy objectives. Forcing increases due to reduced aerosols from ambitious air pollution policies can be mitigated, at least in part, by applying air pollution control and GHG policies together.