URBAG researchers actively participated in the European Geosciences Union (EGU) General Assembly 2025, held in Vienna, Austria, from April 27th to May 2nd, 2025. This year’s event gathered a record-breaking 20,984 registered participants, with 18,646 attending in person from 120 countries, making it one of the largest geoscience conferences in the world.
Three URBAG-related contributions were presented during the week-long event by Qing Luo, Ricard Segura-Barrero and Svetlana Khromova:
Qing Luo presented online her work in the session “Urban Air Quality and Greenhouse Gases”, Ricard Segura presented his poster on site in the session “Understanding feedbacks between greenhouse gas exchange processes and climate variability using in situ observations, remote sensing, and machine learning”, and Svetlana Khromova presented her work in the session “Nature-based Solutions for climate change adaptation: From Concept to Action”.
Presentation by Qing Luo et al.
Cities are hot spots on greenhouse gas (GHG) emissions, yet green infrastructure (GI) such as green spaces and parks provides potential solution for reducing urban carbon footprints through photosynthetic uptake and carbon sequestration. Studies have shown that the offset of urban vegetation uptake on local anthropogenic CO2 emissions varies between 2% and 100%, underscoring the complexity associated with this solution. Quantifying CO2 capture by GI is challenging due to the interplay of photosynthetic uptake and respiration, seasonal variability, the heterogeneous distribution of GI, urban climate, and soil conditions. While biosphere models have been used to quantify carbon exchange processes, they are often employed at the ecosystem level and at coarse spatial resolutions(10-100km), making them insufficient for capturing biospheric signals at the urban scale(10m-1km). Therefore, high-resolution quantification of biogenic CO2 fluxes is essential for understanding their role on urban GHG budget.
This study estimates biogenic CO2 fluxes for 2023 in the Metropolitan Area of Barcelona (AMB) at a 10 m resolution using the Vegetation Photosynthesis and Respiration Model (VPRM). Our approach integrates vegetation indices derived from Sentinel-2, a detailed vegetation land cover dataset constructed by merging local land cover and tree maps, and meteorological inputs (temperature and shortwave radiation) from the Weather Research and Forecasting (WRF) model coupled with an urban canopy scheme that better represents atmosphere exchanges inside the urban canyons. A sensitivity analysis is conducted comparing different VPRM configurations including flux parameterization, input satellite-derived vegetation indices and modifications to land cover map. To constrain the modelled biogenic CO2 emissions and determine their uncertainties, the estimated biogenic fluxes are evaluated with atmospheric CO2 mixing ratios observations from the AMB GHG monitoring network using an atmospheric transport model (WRF-Chem) in a passive tracer approach. This research presents an improved method to estimate the urban biogenic CO2 fluxes and provides guidance for improving and creating more robust ways of accounting for the contribution of urban green to aid policy and urban planners in the design and implementation of GI.
If you are interested in reading the abstract, please follow this link.
Presentation by Ricard Segura-Barrero et al.
ETerrestrial ecosystems play a crucial role in mitigating climate change by reducing greenhouse gas (GHG) emissions and sequestering significant amounts of atmospheric carbon dioxide (CO2). Wetlands, particularly coastal wetlands, are highly efficient carbon sinks but can also be large sources of methane (CH4). Natural and agricultural wetlands, such as rice paddies, contribute to 37 % of global CH4 emissions. Monitoring wetland-atmosphere carbon exchange is essential to evaluate the effectiveness of natural climate solutions (NCS), such as wetlands restoration and sustainable agricultural practices, in reducing GHG emissions and increasing soil carbon storage. Traditional methods for quantifying GHG emissions from wetlands include chamber flux measurements and eddy-covariance flux towers. These techniques provide valuable insights into carbon dynamics at the plot and ecosystem scale levels but fail to capture carbon fluxes at a regional scale, where policy decisions are often made. Recently, atmospheric composition observations have been used at regional scales and over urban areas to constrain the spatial and temporal distribution of GHG fluxes derived from land surface models. Applying similar methodologies to wetland regions, provided sufficient atmospheric observations are available, could enhance understanding of atmospheric carbon dynamics in these areas. The Ebre River Delta, a mixed natural-agricultural wetland system of international importance in terms of sustaining economic activities and biodiversity, offers a unique opportunity to investigate carbon sequestration and GHG emissions. This potential is enhanced by the availability of atmospheric GHG observations from in situ site tower and vehicle transects conducted across the regions.
Here, we integrate advanced modelling techniques and observational data to refine our understanding of GHG fluxes in the Ebre Delta. Biogenic GHG emissions over the Delta are estimated using a high-resolution Vegetation Photosynthesis and Respiration Model (VPRM) adapted for wetland ecosystems for CO2, and the Kaplan model embedded in the Weather Research and Forecasting (WRF) Greenhouse Gas (WRF-GHG) model to estimate CH4 emissions. A sensitivity analysis is performed to compare VPRM CO2 emissions from different model configurations, entailing a default and a wetland-adapted model versions, and two sources of input satellite-vegetation indices, MODIS and Sentinel-2, with contrasting spatial resolutions. Then, modelled atmospheric CO2 and CH4 mixing ratios with WRF-GHG during growing season are compared with in situ observations from the site tower and vehicle transects to assess their accuracy. The framework developed in this study will provide the basis for investigating sequestration and emission hotspots over a mosaic of wetland land-uses and evaluate the region’s potential for climate change mitigation and adaptation.
[pdf-embedder url="https://webs.uab.cat/atmosphere/wp-content/uploads/sites/692/2025/05/poster0410_RS-1.pdf%22]
If you are interested in reading the abstract, please follow this link.
Presentation by Svetlana Khromova et al.
In response to the growing challenges posed by climate change and rapid urbanization, this research investigates the intricate dynamics of stormwater-related urban hazards. It emphasizes the risks and needs arising from environmental injustice, high-intensity rainstorm events, limited combined sewer system capacities, and the prevalence of impervious surfaces. A cross-comparative analysis is conducted in three coastal cities—Barcelona, Boston, and Rotterdam—each with distinct climates and policy frameworks, but facing shared challenges in urban stormwater management. The study advocates for tailored Nature-Based Solutions (NBS) to address these issues while incorporating diverse perspectives to comprehensively evaluate their effectiveness.
The study underscores the urgency of integrating detailed risk assessments with strategic NBS planning to bridge the gap between current urban water management practices and the evolving needs for environmental resilience and societal well-being. A comprehensive framework is established for assessing climate-change-induced hydrological risks, implementing NBS, collecting evidence, and providing actionable guidance to decision-makers.
Adopting a Social-Ecological-Technological Systems (SETS) framework, the research explores the interactions among these interdisciplinary domains. First, it employs a novel methodology that integrates SETS vulnerability, hazard, and exposure factors into a spatially explicit risk score, offering nuanced insights into the impacts of water-related hazards on urban communities (IPCC, 2012; IPCC, 2022). Second, it develops baseline and themed NBS scenarios alongside site potential maps, presenting a systematic and replicable methodology for identifying suitable NBS implementation areas within urban environments. These scenarios account for SETS constraints, categorizing areas from fully feasible to infeasible. Third, the study evaluates the mitigation potential of NBS in reducing vulnerability while enhancing co-benefits, such as thermal comfort, recreation, water storage, habitat provision, and improved water quality.
The findings highlight the multifunctionality of NBS in complementing traditional grey infrastructure while strengthening urban resilience. By integrating natural elements, NBS delivers a wide range of ecosystem services that benefit urban populations. This study emphasizes the critical importance of flexible, forward-thinking, and equitable planning to adapt to climate change.
If you are interested in reading the abstract, please follow this link.