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Overcoming the Carbon Trap in the Global South
Item type: Journal Article
Bretschger, Lucas; Komarov, Evgenij; Leuthard, Matthias (2026)
We construct an overlapping generations model for the Global South in which the choice between dirty and clean technology hinges on the economy’s capital stock, susceptible to climate-induced depreciation. The process of capital accumulation contributes to environmental emissions, yet its intensity can be mitigated through a shift to cleaner production. The tipping point of technological transition is endogenously determined, leading to a diverse range of potential long-term outcomes shaped by capital endowment, pollution intensity, climate vulnerability, and clean factor productivity. Our analysis reveals the possibility of the economy converging into a “carbon trap”, characterized by a sustained equilibrium marked by elevated pollution and diminished income, despite the feasibility of pursuing green growth. Additionally, we present optimal policy measures and simulations that highlight the temporal disparities between the socially optimal timing for transitioning to green technology and the timing dictated by market forces. Finally, to account for the high upfront costs of starting clean production, we extend the model by including a non-convexity in the production structure of the clean technology.
Beyond annual dose: Assessing lifetime cancer risk from dietary radiocesium exposure and public risk-perception gaps in Japan
Item type: Journal Article
Liu, Yuxin; Zhuang, Qian; Dong, Shipeng; et al. (2026)
Radiocesium in food poses an ongoing challenge in environmental health risk assessment. Annual dose compliance (1 mSv/year) is essential for radiological protection but may not reflect cumulative lifetime cancer risk (LCR) under chronic exposure or corresponding public risk perceptions. We developed an integrated radiological risk assessment framework to evaluate dietary radiocesium-related health risks and determine whether these estimates align with public risk perceptions. We estimated prefecture-level LCR and risk-perception gaps through multilevel regression and poststratification using a nationwide survey in Japan, together with food-monitoring data on radiocesium concentrations. The annual dietary radiation dose was well below the 1 mSv/year benchmark, while modeled mortality and morbidity LCRs remained above 10-5, ranging from 1.84 × 10-5 to 1.37 × 10-4 and from 2.70 × 10-5 to 2.02 × 10-4, respectively. The high-risk prefectures, particularly in Tohoku identified in spatial analyses, warrant prioritized monitoring. Agricultural products were the dominant exposure pathway, accounting for approximately 55.0–64.5% of the estimated LCR. Estimated risk tended to exceed perceived risk in northern Japan, indicating a need for proactive risk control, whereas perceived risk tended to exceed estimated risk in central Japan, suggesting a greater need for targeted communication. Our framework supports region-specific monitoring and communication by considering the LCR alongside annual dose metrics.
Admixtures for low-carbon cements
Item type: Journal Article
Dengler, Joachim; Gädt, Torben; Moghul, Sirajuddin; et al. (2026)
Low-carbon cements with reduced clinker factors increasingly rely on high-specific-surface-area supplementary cementitious materials (SCMs), notably calcined clays and emerging recycled fines. These binders often exhibit increased water demand, faster workability loss, and reduced early strength relative to ordinary Portland cement (OPC) and blended cements with fly ash or slag, thereby challenging the robustness of conventional admixture formulations. This review synthesizes current mechanistic understanding of how superplasticizers and hydration-controlling admixtures govern hydration kinetics and fresh-state performance in composite cements, with an emphasis on calcined-clay systems. For polycarboxylate ether (PCE) superplasticizers, we discuss structure–activity concepts in terms of adsorption, evolving surface area during early ettringite formation, and the effects on C₃S dissolution and C-S-H/CH nucleation. For accelerators and strength-enhancing admixtures, we evaluate calcium salts, alkanolamines, and C-S-H seeding, highlighting their impact on the hydration of SCM-rich binders. For retarders, we compare dissolution-, nucleation-, and growth-controlled mechanisms and explain how the presence of SCMs alters them. Finally, we connect the hydration processes of low-carbon cements to rheology through surface coverage, time-dependent specific surface area, particle packing, and the percolation threshold, and identify key knowledge gaps for predictive admixture design in low-carbon concretes.
Historic residential segregation impacts biodiversity data availability disparately across the tree of life
Item type: Journal Article
Ellis-Soto, Diego; Chapman, Melissa (2026)
Historical residential segregation policies have left a lasting impact on urban environments, greenspaces, and wildlife communities, creating socioeconomic heterogeneity and altering biota. However, the extent to which these policies continue to impact urban biodiversity remains unclear, especially across taxonomic groups and spatial scales. We explore how sampling and biodiversity metrics (sampling density, estimated completeness of sampling, and expected species richness) across taxonomic groups vary across historically redlined neighborhoods and relative to broader urban areas. To explore these patterns, we leverage nearly 60 million observations of amphibia, aves, fungi, insecta, mammalia, plantae, and reptilia collected between 2000 and 2020 within 145 Metropolitan Statistical Areas in the United States. We estimate significant differences in sampling density across redlined neighborhoods for all taxonomic groups, with the lowest values found in areas previously redlined. Estimated completeness of biodiversity inventory was low (average ~42% across all taxa) and varied significantly by Home Owners' Loan Corporation (HOLC) grade for birds, mammals, and plants. Expected richness varied significantly by HOLC grade only for birds. Our findings highlight how differences in biodiversity sampling may not translate to differences in expected species richness patterns and suggest that applying insights obtained from certain taxonomic groups and extrapolating to multiple others may not be appropriate. Urban wildlife communities are not well-documented despite the explosion of digital information, and what is documented is known to be biased along gradients of housing segregation and multiple urban scales. These findings add evidence to suggest long-lasting effects of legacies of segregation on the natural world.
Limiting warming by CO₂ and methane mitigation in an expanded scenario space
Item type: Journal Article
Weber, Konstantin; Knutti, Reto; Brun, Lena; et al. (2026)
Anthropogenic methane (CH4) currently contributes more than 0.6 ∘C to global warming, and CH4 mitigation is a powerful option to limit near-term warming. Assessments of greenhouse gas (GHG) mitigation rely on Integrated Assessment Model scenarios with typically non-linear emission trajectories (due to economic optimization) and similar mitigation ambition for CO2 and CH4. However, climate targets are often linear and focused primarily on CO2. Here, we present a complementary scenario generation approach to systematically map peak warming resulting from two political choices: the net zero emissions year for CO2 or GHG after linear reductions, and the simultaneous change in CH4 emissions. We show that without CH4 mitigation, peak warming exceeds 1.7 ∘C (50% likelihood), and the likelihood of keeping warming below 2 ∘C drops below 50% with net zero CO2 emissions after 2050. Irrespective of CH4 mitigation stringency, limiting warming to 1.5 ∘C is no longer plausible. An additional sustained linear 10% reduction in CH4 emissions (~ 35 MtCH4/year) until 2050 increases the 2 ∘C-compatible remaining carbon budget by ~ 165 GtCO2. These results emphasize the benefit of near-term CH4 mitigation.