Sergio Alvarez

The environmental implications of linear infrastructure —such as roads, railways, and pipelines— require robust tools for assessing impacts and benefits. This study presents a systematic review of tools and methods used in high-impact publications between 2021 and 2024, focusing on case studies that evaluate environmental performance across the entire infrastructure project life cycle: planning, design, construction, operation, maintenance, and end-of-life. The review analyzes 102 peer-reviewed articles and strategic documents. Tools are classified by type (e.g., solutions, services, corporate frameworks), life cycle coverage, goal definition, system boundaries, data quality, and assessment methodology. Results show a fragmented but evolving landscape. Impact assessments are heavily concentrated in construction (69%) and operation phases (78%), while maintenance (53%) and end-of-life stages (37%) remain underrepresented. Spatial modeling, ecological indicators, and Life Cycle Assessment (LCA) are among the most frequently applied approaches (45%, 32% and 27%, respectively). However, structured evaluation of environmental benefits is rare: 70% of studies include no assessment of ecological gains, and none incorporate economic valuation. Comparative evidence indicates that many of these limitations —particularly methodological fragmentation, weak life cycle coverage, and the lack of integration between spatial and technical approaches— have persisted for more than a decade, despite sustained attention in the literature.

1. Cities’ growing centrality in the path toward climate neutrality is inseparable from their expanding share of global greenhouse gas (GHG) emissions (Hoornweg et al., 2011; IPCC, 2023; Wiedmann e...

Carbon dioxide (CO₂) enrichment using fuel combustion is widely applied in greenhouse production. However, its implications for air quality and occupational safety under real operating conditions remain insufficiently characterized. This study evaluates a propane-based CO₂ enrichment system in an advanced greenhouse. The analysis integrates CO₂ dynamics, combustion-derived pollutants, and occupational exposure. High-resolution monitoring at 5 min intervals was conducted in an enriched module and a control module over a five-month period. Two operational modes were assessed: continuous and diurnal-only enrichment. The system maintained CO₂ concentrations within agronomic targets. Mean values reached 1200 ppm and 940 ppm for continuous and diurnal operation, respectively. However, significant CO₂ losses were observed due to ventilation. The maximum enrichment efficiency, expressed as the Combustion Efficiency Index (CEI), was 2.67 × 10⁻³. Combustion-related pollutants (CO, NO, NO₂, SO₂, and O₃) showed transient peaks during burner activation. However, concentrations remained below occupational exposure limits when evaluated using time-weighted averages. The incomplete combustion ratio (ICR) remained stable at approximately 1.9 × 10⁻³. This indicates predominantly complete combustion. These results provide field-based evidence on the performance and safety of propane-based CO₂ enrichment systems. They also highlight the importance of continuous monitoring and improved CO₂ retention strategies in semi-confined greenhouse environments.

The maritime shipping sector, responsible for transporting 90% of global trade and contributing 2-3% of anthropogenic greenhouse gas emissions, faces intensifying pressure for transparent carbon accountability as regulatory frameworks like the EU's Carbon Border Adjustment. In spite of this urgency to report transparently, systematic assessment of disclosure quality within the sector remains limited. This study conducts the first comprehensive evaluation of carbon footprint transparency among the world's 16 leading container shipping companies, representing over 75% of global capacity, using an adapted Carbon Integrity Index methodology. Results reveal substantial heterogeneity in disclosure quality, with CIX scores ranging from 1.2 to 8.6 (mean: 5.72), and no meaningful correlation between operational scale and transparency performance. Half of the analyzed companies demonstrate systematic gaps between operational emissions disclosure (Scopes 1 and 2) and value chain emissions (Scope 3), with very marked deficits reaching 0.77 points of 1. Most critically, zero companies provide uncertainty quantification, creating false precision that prevents stakeholders from assessing data reliability. Theoretical analysis through legitimacy, agency, and institutional theory lenses suggests companies prioritize administratively convenient operational disclosures while avoiding complex value chain transparency. These findings illustrate the limits of voluntary reporting mechanisms, in an evolving landscape characterized by more stringent demands for carbon accounting information. This study establishes a critical baseline for the sector's transparency transition and identifies governance capacity rather than technical constraints as the primary determinant of disclosure quality.

The rise in greenhouse gases underscores the urgency of carbon dioxide removal (CDR) as a complement to emission reductions. Enhanced rock weathering (ERW) holds promise by coupling geochemical carbon sequestration with agronomic benefits, although integrative experimental evidence remains limited. This study evaluated two amendments (recycled concrete in wheat, C₃, and basalt in maize, C₄) under ambient and elevated CO₂ conditions (~1000 ppm). Conducted in a greenhouse over 21 weeks using loam soils, the experiment evaluated four treatments comprising three different particle-size ranges (2 enhanced biomass, particularly vegetative biomass in wheat (+42.6%) and root biomass in maize (+55%), without significantly increasing yield. In wheat, particle size was decisive: intermediate fractions (2–6 mm) yielded the best results. In maize, basalt effects were less consistent. Concrete amendments increased soil pH and carbonate content, especially with coarse particles and elevated CO₂, whereas basalt-induced responses were slower and more variable. These findings confirm the potential of ERW as a dual climate–agronomic strategy while highlighting the need for long-term, field-scale validation.

The methodology used to attribute greenhouse gas (GHG) emissions to nations profoundly influences perceived climate action burdens, raising critical questions about equity in global climate governance. This study systematically evaluates current production-based accounting (PBA) by comparing it with three alternative frameworks: consumption-based accounting (CBA), historical cumulative-based accounting (HBA), and per capita-based accounting (PCBA). We conducted a comprehensive SWOT analysis using multi-stream evidence synthesis, analyzing 23 major emitting countries representing over 80% of global emissions. Data sources included UNFCCC documents, historical emission datasets, consumption-based emission data, and World Bank population estimates. Results reveal dramatic redistributions of national positioning across frameworks, with countries experiencing extreme ranking volatility—India dropped 19 places from 4th under PBA to 23rd under PCBA, while Saudi Arabia rose from 11th to 1st. Our analysis demonstrates that while accounting frameworks provide factual measurements of different emissions dimensions, their selection for policy purposes constitutes a normative choice with distributional consequences. We explicitly map each framework to the responsibility principles it operationalizes, revealing that current over-reliance on PBA creates systematic blind spots in the policy context and climate governance.

The use of Cross-Laminated Timber (CLT) panels in buildings offers earthquake resistance with a low carbon footprint. However, significant seismic displacements can cause damage, raising concerns about the long-term embodied carbon balance obtained, particularly if significant interventions are required to restore the original functionality. This study embraces a systematic review of innovations considered for massive timber structures in seismic zones, focusing on embodied carbon emission reduction. The analysis undertaken is based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) using the Scopus and Web of Science database references published from 2010 to 2025. A total of 53 documents meeting the search criteria were identified and assessed, considering their degree of technological maturity (TRLs). The results highlight efforts toward innovation in the performance of connections and lateral stabilization to minimize damage and enhance reparability, revealing the need to link new practices and technologies to the structural and environmental results of the solution, particularly in terms of efficiency in the use of materials about their possible repair and reuse at different stages of the life cycle. The availability of innovations aimed at carbon footprint reduction, and which present a high degree of technological maturity is reviewed and the potential of these solutions is evidenced in places where seismic vulnerability greatly influences the design; combining performance with the aim of achieving a carbon-neutral economy.

Corporate carbon emissions reporting is central to climate accountability, yet significant gaps remain in transparency, completeness, and methodological rigor. This study introduces the Carbon Integrity Index (CIX), a structured framework for assessing disclosure quality through ten indicators covering Scopes 1, 2, and 3. Unlike existing standards focused on reporting requirements, the CIX evaluates how well emissions are reported, addressing methodological transparency, scope coverage, and treatment of uncertainty. Applied to 2022 sustainability reports from companies listed in Spain’s IBEX 35 index, the framework reveals an average score of 5.7/10, with 69% of firms achieving passing results. While Scope 2 reporting was generally robust (mean: 0.82), Scope 3 disclosures—often representing the majority of emissions—and uncertainty assessments were systematically weak (mean: 0.08). Findings provide empirical support for legitimacy and institutional theory, showing how formal compliance can mask performative compliance that limits meaningful accountability. Sectoral differences suggest that institutional pressures and operational complexity shape divergent transparency pathways, raising concerns that universal standards may entrench reporting disparities. The CIX offers regulators, investors, and companies a practical tool for distinguishing symbolic from substantive disclosure, enabling more informed decision-making and strengthening the role of reporting in driving the transition to net-zero business models.