Turbulence-driven nutrient supply has the potential to shape bottom sea ice microbial communities, affecting the balance of O2 uptake and release which defines the net community production (NCP) of the ice. This study contrasts sea ice NCP at two sites with comparatively high and low under-ice turbulent conditions. These locations were sampled over a 4-week spring bloom period in the Dease Strait region of the Kitikmeot Sea near the community of Cambridge Bay and the Canadian High Arctic Research Station (CHARS). We found that strong under-ice tidal currents promoted nutrient replenishment into the bottom ice, often supporting increased sea ice algal growth and a net autotrophic (i.e., net release of O2) signal of NCP throughout the study period. However, the stronger currents also accelerated bottom-ice melt and led to periodic reductions in ice algal chlorophyll a and times of net heterotrophy (net uptake of O2). In contrast, the location of lower turbulence and more stable currents presented more limited chlorophyll a accumulation and a persistent heterotrophic signal of NCP, potentially driven by a greater proportion of heterotrophic bacterial activity within the ice. These observations of contrasting NCP demonstrate the spatio-temporal complexity of bottom-ice algal blooms in the Arctic and challenge the use of a singular autotrophic bloom phenology to describe their seasonal growth. Rather, we show that the phenology of bottom-ice algal bloom development and the balance between autotrophic and heterotrophic activity vary with the sub-ice turbulent regime.
This article interrogates how intermediaries enact various visions of sustainable futures within the contingencies of entrenched regime structures in the present, through a cross-case comparison of actors working to advance 3 alternative agricultural production systems in the U.S. Midwest: winter annual oilseeds, the perennial grain Kernza®, and managed grazing systems. Intermediaries (e.g., renewable energy consultants, NGO policy advocates, agri-food supply chain coordinators) have been theorized as important agents of change in sustainability transitions. Here, they are reframed as useful entry points to understanding niche-regime interactions in realizing diverging interpretations of sustainable agri-food systems. Methodologies based in work calendar logging, ego-network mapping, and interviews revealed distinct time allocation patterns and unique network compositions across the 3 cropping systems, providing rich insight into the day-to-day practice of intermediary actors. Results showed that actors were pursuing multiple visions of agri-food sustainability, ranging from minimizing the harms of the incumbent regime while leaving it largely intact, to more transformative approaches based on organizing watershed-based learning hubs to support community-led transitions. Interestingly, some intermediaries worked across multiple crops and cropping systems, but were enacting different versions of sustainability simultaneously in those systems. For the perennial grain Kernza, its networks were overwhelmingly composed of intermediary actors. Broadly, findings suggest that intermediaries can maintain, reform, or transform systems, so tracking their activities can better illuminate whom, what, and where is being sustained in a given agri-food transition.
Climatic changes in the physical environment modulate biogeochemical cycles, biodiversity, and trophic interactions in the Central Arctic Ocean (CAO). Physical processes and sea-ice conditions are highly seasonal in the CAO and dependent on interactions that occur throughout the evolution of the upper ocean–sea ice–lower atmosphere system. Understanding these seasonal interactions is critical to comprehending and predicting the long-term trends as the CAO moves towards ice-free summers and to informing future policy decisions at the core of ongoing discussions concerning the CAO Fisheries agreement, for example, at the Arctic Council and International Council for Exploration of the Sea working group on the CAO. Here, we review current knowledge of the physical environment, biogeochemical cycles, and biodiversity in the waters of the CAO, identify emerging research questions, and introduce the science plan for the first Tara Polaris drift onboard the Tara Polar Station to advance knowledge and address these questions. Despite increased observational programmes in the CAO over the past years, for example, the Nansen and Amundsen Basin Observational System (NABOS) and Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), extensive knowledge gaps remain in relation to ocean stratification, sea ice and lightscape, nitrogen fixation and nutrient fluxes, carbon export and transfer, sympagic-pelagic coupling, aerosol production, contaminant transport and transformation, chronobiology, and fish distribution. Further knowledge on overall CAO biodiversity, ecosystem functionality and interannual variability is also critically needed. We describe a way forward to address these knowledge gaps using ice-tethered and profiling instruments coupled with multi-omics, culturing, and imagery approaches deployed from Tara Polar Station during the first of ten Tara Polaris drifts designed to facilitate detection of interannual variability and change over time.
Near-term climate forcers (NTCFs), including aerosols and chemically reactive gases, influence both climate and air quality. However, the impact of NTCFs on internal climate variability is unclear. This study investigates how reductions in NTCFs affect Arctic Oscillation (AO) in the near future, using the Aerosol and Chemistry Model Intercomparison Project. Reduced NTCFs increase the occurrence of the positive AO in the near-future period. We suggest that reduced NTCFs modulate the atmospheric mean-state toward a more positive AO-like structure by increasing the meridional temperature gradient, thereby shifting the zonal-mean zonal wind poleward. The frequent occurrence of a positive AO further contributes to enhanced surface warming across the Northern Hemisphere in the near future. Therefore, a comprehensive understanding of the diverse impacts of NTCFs on internal climate variability is essential for effectively managing future NTCFs emissions.
Despite notable reductions in precursor emissions, ambient ozone levels continue to increase in many urban areas, including Seoul, South Korea. This study examines the photochemical ozone production process in the Seoul Metropolitan Area using observational data from the Korea-United States Air Quality (KORUS-AQ) airborne campaign. By analyzing hydroxyl radical reactivity linked to nitrogen oxides (NOX) and volatile organic compounds (VOCs) (RNOx/RVOCs), we identify a shift from a NOX-saturated regime during the low-ozone period toward a transitional regime during the high-ozone period. Observed increases in VOC reactivity relative to NOX reactivity correlate with higher ozone production. We use a 0-D box model with observational constraints to generate ozone isopleths under different photochemical conditions. The results indicate that the isopleth varies significantly depending on atmospheric trace gas composition even in the same location with differences in trace gas mixtures, mostly driven by VOCs. RNOx/RVOCs generally correlate well with traditional metrics such as CH2O/NO2 and ozone production efficiency. However, the correlation becomes less reliable as the ozone production regime approaches the transitional regime. Our findings highlight the limitations of static regime classifications and emphasize the importance of dynamic, observation-based indicators for guiding ozone pollution control strategies.
Micronekton communities in the oxygen minimum zone of the eastern Clarion-Clipperton Zone, Pacific Ocean, have been largely undescribed below 300 m depth. Yet, these communities could soon be impacted by deep-sea nodule mining. Deep-sea mining activities pose potential impacts to midwater ecosystems, including sediment plumes and release of dissolved metals that may be depth-specific but carried through the water column by vertically migrating organisms. Gathering baseline data on vertical distributions and migrations is thus essential. Micronekton samples were collected in spring and fall of 2021 from 0-1500 m depth during the day and night, utilizing a 10 m2 mouth-opening Multiple Opening Closing Net and Environmental Sensing System, at both a control site (intended for monitoring against mining impacts) and mining site, in the NORI-D area licensed by Nauru Ocean Resources, Inc. We found high amounts of migrating biomass moving at night from the lower oxycline and core of the oxygen minimum zone into the upper oxycline (1.9 & times; increase for fishes) and into the epipelagic zone (8.0 & times; for fishes, 29.4 & times; for crustacea excluding euphausiids, and 45.6 & times; for euphausiids). We documented the vertical distributions and migration patterns of 52 taxa, finding 22 vertical migrators and 30 non-migrating taxa. Micronekton diel vertical migration patterns and vertical distributions corresponded to spatiotemporal changes in oxygen concentrations (and other potential factors that are not part of this article but reported in a companion study) and many seasonal shifts in distributions at both the broad taxonomic level and species level were observed. We found shifts in populations of different species of the genus Cyclothone that may be due to changes in water masses or currents. Given these results, particularly evidence of significant seasonal shifts, we considered how deep-sea mining discharge plumes may affect the mesopelagic micronekton community in the CCZ.
We address the need for more accurate and effective monitoring of methane emissions from landfills by reviewing traditional and emerging emissions detection, localization, and quantification field-based technologies. This review explores the advantages and limitations of current and emerging technologies and defines each monitoring technology as a system composed of a platform, sensor hardware, and data post-processing. Mathematical models (e.g., Landfill Gas Emissions Model (LandGEM)) are briefly discussed but are not the focus of this review. We note that, among the current technologies used for landfill monitoring, some are widely accepted by regulators but are not necessarily well-proven scientifically to be accurate and reliable methods for monitoring landfill methane emissions. We discuss the accuracy and coverage limitations of widely used and traditional approved methods such as manual walking surface emissions monitoring (SEM) and unmanned aerial vehicle (UAV) SEM. We note that mature technologies, such as mobile tracer correlation and aircraft-based flux measurements, provide reliable estimates of emissions rates but lack leak localization, and mobile vehicle-based measurements provide accurate emission estimates at relatively lower cost. Advanced technologies like aerial imaging and Light Detection and Ranging (LiDAR) offer quantification and localization despite unresolved uncertainties. Emerging technologies, including UAV flux plane and UAV column methods, satellite imaging, and remote point fixed sensors, have strong potential for cost-effective and scalable deployment, though many still require methodological improvements to improve their emission quantification accuracy. Any of the quantification technologies discussed in this review can be used to provide a snapshot of the methane emissions from a landfill. However, it should be remembered that none of the technologies can provide a robust annual inventory from a single measurement. A robust annual inventory requires repeated measurements over time and a combination of complementary technologies to capture all emission sources.
Despite extensive research on the effects of elevation on photosynthetic performance and genome characteristics in alpine plants, little is known about how synanthropic, lowland-origin species respond genetically and physiologically when colonizing high-elevation environments. In particular, the combined responses of genome size variation, ploidy structure, and photosynthetic pigment content along elevational gradients remain poorly understood for polyploid plant complexes exposed to strong anthropogenic pressure. Achillea millefolium is widespread in the Karkonosze Mountains across a wide elevational range, occurring in both natural and synanthropic habitats. We collected samples along a 1,000-m elevational gradient to assess how genome size and chlorophyll content vary with elevation and to explore genetic variation between populations. We conducted single nucleotide polymorphisms analysis using Diversity Arrays Technology Sequencing (DArT-seq) and measured genome size and chlorophyll content from the same individuals. Our results show that both genome size and chlorophyll content decrease with increasing altitude. Crucially, the presence of A. millefolium was closely associated with tourist infrastructure, suggesting that human-mediated corridors facilitate its upward migration. At higher elevations, the dominance of hexaploids suggests that higher ploidy levels may support survival in harsh climates. This study identifies polyploidy and genome downsizing, alongside the plastic modulation of photosynthetic pigment levels, as key mechanisms enabling the persistence and potential adaptation of this synanthropic species in harsh mountain environments. These findings demonstrate how such colonizing populations navigate environmental pressures at high altitudes through integrated genomic and physiological shifts, providing a foundation for understanding how plants may adapt to and thrive in new ecological niches, potentially guiding ecological management in other mountainous regions.
Municipal solid waste (MSW) landfills are major methane sources, yet regulations still rely on U.S. EPA Method 21 Surface Emissions Monitoring (SEM) or similar protocols developed for industrial leak detection and defined by 30-m traverse spacing and a 500 ppmv action threshold. Despite long use, its probability of detection (POD), minimum detection limit (MDL), and emission-reduction potential at MSW landfills have not been quantitatively characterized. We present the first systematic evaluation of Method 21 SEM through 3 components: (1) synthetic Gaussian plume modeling of how spacing, threshold, and atmospheric stability control the 90%-POD MDL; (2) controlled-release SEM campaigns at the Simulation Facilities for Large-scale Emission Experiments (SIMFLEX)-Landfill to derive field-based 90%-POD MDLs for 30-, 15-, and 7.5-m spacing and 500, 200, and 50 ppmv thresholds; and (3) application of these MDLs to emission distributions from 8 Canadian landfills, comparing SEM with unmanned aerial system (UAS) column and tube-based surveys and aerial light detection and ranging (LiDAR), including an illustrative cost-normalized methane detection metric. Modeling and field data show that the regulatory configuration (30 m, 500 ppmv) yields a 90%-POD MDL of 98 kg/h, meaning only the largest plumes trigger action. Using 7.5-m spacing and a 200 ppmv threshold lowers the MDL to 13 kg/h but increases survey effort and false positives. Applied to real emission profiles, the regulatory configuration detects <10% of individual sources on surfaces where SEM can be deployed, because most emit below 98 kg/h. Even with optimized settings, SEM detects a smaller share of total emissions than aerial LiDAR (70%-90%) or UAS methods (20%-54%) and yields lower cost-normalized detection return under the representative procurement assumptions used here. These results demonstrate that incremental modifications to Method 21 are unlikely to bridge SEM's performance gap or provide the sensitivity and cost-normalized detection performance needed for effective landfill methane monitoring.
Micronekton are a vital part of midwater food webs and have the potential to be impacted by deep-sea mining via the release of sediment plumes, including dissolved metals. Micronekton communities in the Clarion-Clipperton Zone (CCZ) region of the eastern Pacific Ocean have been studied very little; baseline community descriptions are needed should mining commence. Micronekton samples were collected from 0 m to 1,500 m during the day and night in spring (March-April) and fall (October-November) of 2021, prior to mining activities, utilizing a 10 m2 Multiple Opening Closing Net and Environmental Sensing System. Trawls were conducted at both a Preservation Reference Zone (intended for monitoring against mining impacts) and a designated mining site (approximately 60 nautical miles or 111 km apart) in the NORI-D license area of the eastern CCZ, licensed to Nauru Ocean Resources Inc. by the International Seabed Authority. We found higher springtime densities and biomasses of fishes, crustaceans, and cephalopods compared to fall samples, principally due to juvenile recruitment. Micronekton community composition and seasonal patterns in biodiversity levels were distinctly different between the sites. Seasonal differences were likely driven by primary productivity and the seasonal dynamics of the North Equatorial Current, North Equatorial Countercurrent, and eddies. Differences in abundances and biomass between sites suggest that the control area may not be representative of the mining site. Due to the oceanographic variability found in NORI-D, and the lack of long-term time-series studies in the CCZ, additional sampling is needed to establish a sufficient baseline from which the potential impacts of deep-sea mining could be separated from natural variation.
Soil physics directly influences environmental health and quality by determining the exchange, movement, and retention of water, gas, and solutes in soils. Despite this key role, soil physical properties in urban environments remain understudied and frequently overlooked in urban planning and sustainable design, leading to missed opportunities for enhancing beneficial urban soil functioning, for example, for stormwater runoff management. Due to the ongoing climate crisis, urban water-soil management is becoming relevant for improving ecosystem services, including resilience to water scarcity, droughts, and flooding. Thus, the potential of urban soil physical studies, for example, mapping, modeling, and in situ characterization, for promoting healthier urban environments is discussed in this review. The focus is set on 3 current challenges in urban soil physical studies: (1) degradation of soil physical functions in the urban context, (2) lack of data on urban soil physical properties, and (3) the lack of a standardized taxonomy for urban soils classification. These challenges obscure the understanding of hydrological ecosystem services and urban soil functioning. Conversely, this review identifies key opportunities to advance the field, including (1) multiscale analysis of urban soils, (2) new technologies for determining soil hydraulic properties, and (3) the development of hydraulic functional soils. These advancements could improve urban soil management and enhance the climate change resilience of cities, contributing to healthier urban environments.
Agroecology must reach more people and more territories to confront the current socioecological polycrisis of which food systems are part and parcel. A central challenge is that agroecological knowledge emerges from particular territorial contexts and may not be easily applicable in others. Therefore, situated scaling approaches that foster local innovation and rhizomatic connections among territories are called for. We approach this challenge through analysis of action research collectives working in Peru, Ecuador, Colombia, Nicaragua, Guatemala, Mexico, and Cuba, under the umbrella of the “Participatory Research in Agroecology in Latin America and the Caribbean” project. We sought to add nuance to our understanding of agroecological scaling by exploring how each collective approached scaling and its drivers, the bottlenecks they confronted, and the solutions they piloted. The collectives’ work responded to several dimensions of agri-food system transformation: agroecological farming, local governance, favorable markets, and biocultural systems. They codesigned solutions adapted to each territory, including peasant experimentation to test agroecological practices, horizontal learning processes, and the articulation of fair markets associated with participatory guarantee systems, peasant identities, and indigenous cultures. Contextualized in this way, agroecology contributes to the defense of peasant and indigenous ways of life while learning from each territorial experience. Networks fostering learning, exchange, and advocacy strengthened these initiatives locally and broadened their reach, allowing for situated scaling. The set of experiences demonstrates the power of intersectoral collaboration for articulating fairer and more sustainable agri-food systems. It also revealed barriers to collaboration, particularly between academia and other sectors, as well as the need for approaches that foment full participation of women and youth. The collectives confronted a broad set of structural constraints for situated scaling that underline the importance of methodological flexibility, as well as solidarity and alliances with other emancipatory movements. Please refer to Supplementary Materials for a full text Spanish version of this article.
Transdisciplinary research is increasingly recognized as essential for addressing complex, real-world challenges. Collaboration across disciplines is fundamental to transdisciplinary inquiry, necessitating deliberate consideration of the methods used to organize gatherings that enable such collaboration. This article explores the convening methodologies of the Ocean Memory Project (OMP), an initiative blending scientific inquiry with artistic expression and other forms of knowledge. OMP’s framework for structured gatherings goes beyond logistical necessity to function as a core transdisciplinary research methodology. OMP convenings have emphasized place-based experiences, the integration of varied knowledge practices, and the establishment of values fostering inclusivity and collaboration. OMP convening activities, including Story Circles, experiential activities, and interacting in innovative virtual environments, cultivated a culture of listening and epistemological humility, and catalyzed new forms of knowledge and creative exploration, as well as contributed to a growing understanding of how convening can support integrative research and creative communities. The convening methods developed and honed by OMP are living concepts, described and brought forward here for adoption and adaptation by other groups with similar interests in collaborative inquiry. Specific recommendations to other transdisciplinary conveners are to foster early integration of perspectives, create safe and inclusive spaces that explicitly welcome all voices, recruit participants as organizers, reverse the relationship between speaker and audience, encourage emotional engagement, and provide opportunities for unstructured time and space.
Primary aerosols play a critical role in polar climate systems, influencing cloud formation, precipitation, radiative balance, and surface energy budgets. This paper provides a comprehensive synthesis of primary aerosol sources, transformation and removal processes, and broader atmospheric impacts in polar regions, emphasizing their links to ocean and sea ice biogeochemistry. These aerosols (including sea salt, primary organic aerosol, and primary biological aerosol particles) originate from marine and cryospheric environments and are emitted through physical processes, such as wave breaking, bubble bursting, and blowing snow. Emission sources include seawater, sea ice, snow, and freshwater from river discharge and glacial runoff. Once airborne, these particles can serve as a chemical reservoir, influencing atmospheric composition and reactivity, and as seeds for cloud droplet and ice crystal formation, influencing cloud microphysics and polar climate. Despite their importance, many of the processes governing primary aerosol emissions and transformations remain poorly constrained. The most pressing knowledge gaps pertain to emission processes, limited spatiotemporal observational coverage, instrumentation constraints, parameterization development, and the integration of interdisciplinary expertise. To improve our understanding of primary aerosol drivers and their response to climate, future research efforts should prioritize strategically coordinated and cross-disciplinary process studies, advancements in measurement technologies and coverage, and close collaboration between modelers and observational scientists to inform and refine model parameterizations. As polar regions continue to undergo profound changes marked by increased precipitation, reduced sea and land ice, freshening oceans, and shifting ecosystem dynamics, characterizing present-day primary aerosol populations is vital. Improved understanding will be essential for anticipating future changes in aerosol-radiation and aerosol-cloud interactions and their implications for polar and global climate systems.
Polar oceans and sea-ice regions are global hot spots for the production of biogenic volatile methylated sulfur (VMS) compounds: dimethyl sulfide (DMS) and methanethiol (MeSH). VMS compounds make important contributions to atmospheric particle formation and cloud property modulation, especially when polar atmospheres are pristine. As a result, the polar biogenic sulfur cycle may induce significant climate feedback in response to ongoing sea ice decline. However, polar VMS production, emission, and atmospheric oxidation processes remain poorly represented in current numerical models, hampering assessments of their radiative impacts and, in turn, implementation of targeted observations necessary for providing predictive understanding of changes in the ocean–sea ice–atmosphere (OIA) system. We synthesize current knowledge of the polar biogenic sulfur cycle and its representation in models. To untangle the existing gaps and provide a roadmap toward predictive understanding, we identify key features of sea ice habitats for biological VMS production, sea ice physical features that enhance or suppress VMS emissions, and atmospheric VMS oxidation at low temperatures that controls the contribution of oxidation products to particle formation or growth. These features are tightly coupled, emphasizing the need for coordinated efforts across disciplines that span the OIA interface, and among observational, experimental, and modeling communities. We recommend 4 priority research areas: (1) model representation of biological VMS production at the sea ice bottom and surface; (2) improved quantification of cloud condensation nuclei (CCN) sensitivity to VMS emissions with updated gas phase and multiphase oxidation chemistry at low temperatures; (3) better spatial and seasonal quantification of MeSH abundance and its biological and chemical controls in sea-ice environments; and (4) assessment of the contribution of episodic extreme VMS emissions during sea ice breakup for the polar CCN budget.
Halogen radicals have long been recognized for their role in depleting ozone in the stratosphere and in polar and pristine maritime boundary layers. Over the past 2 decades, an expanding body of research has highlighted the significant influence of halogen radicals on atmospheric chemistry and air quality degradation in anthropogenically impacted maritime and continental regions. This article reviews recent advances in the study of reactive halogens in polluted environments, with a particular focus on China, covering atmospheric observations, emission sources, chemical transformations, and the effects on atmospheric oxidation processes and the levels of ozone and secondary aerosol. Key recent findings include: (1) the widespread detection of photolabile halogen gases such as ClNO2 and dihalogens across various locations; (2) the substantial impact of halogen radicals, particularly those derived from elevated daytime Cl2, on VOC oxidation, the HOx budget, and the concentrations of ozone and secondary aerosol; (3) significant progress in identifying anthropogenic sources and chemical activation pathways for chlorine and bromine; and (4) the underrepresentation of daytime halogen activation processes in mainstream chemical transport models, leading to a likely underestimation of their atmospheric impacts. Future research efforts should include (1) conducting comprehensive and updated field measurements of halogens in diverse and changing environments and targeting emerging halogen, (2) improving understanding of sources and chemical cycles of halogen species, and (3) enhancing the capability of air quality models in simulating reactive halogen impact in polluted regions.
The role of traditional Indigenous agriculture in preserving native maize in Mexico has been widely researched, as well as its cultural and environmental benefits. Nevertheless, the extensive and interdisciplinary literature on landrace maize production has paid less attention to the role of women’s knowledge in transforming maize into handmade tortillas, work that contributes directly to the conservation of maize agrobiodiversity, food culture, and identity. In rural Mexico, maize provides the basis of local food systems, and the transformation of this grain into handmade tortillas is intricately related to fuelwood use as the primary source of cooking energy. The notion of food sovereignty in rural Mexico must consider energetic needs and address the health and environmental implications of women’s work in maize processing. This review examines the intersection of energy use and women’s role in native maize processing activities and conservation. We explore fuelwood use in handmade tortilla making and draw a parallel between the conservation of landrace maize agro-food systems and energetic justice. Drawing on the experiences of Indigenous women dedicated to making and selling tortillas in Purepecha, Zapotec, and Mixtec communities, we illustrate their role as key articulators of native maize conservation while discussing the environmental and health implications of this livelihood. Ultimately, we argue for the need to seriously consider the tensions between native maize conservation and energy justice as essential for constructing sustainable and sovereign livelihoods in Mexico’s rural communities. Please refer to Supplementary Materials for a full text Spanish version of this article.
Accurate knowledge about urban carbon dioxide (CO2) emissions is essential to support effective climate change mitigation. Yet large discrepancies among emission inventories within cities highlight the need for well-designed atmospheric CO2 sensor networks that can deliver independent CO2 emission estimates. Most cities still lack observation systems capable of meeting this challenge. We conducted Observing System Simulation Experiments (OSSEs) for 2 German cities, Berlin and Munich, to assess how the number, quality, and placement of in situ CO2 sensors affect the ability to quantify city-wide emissions under various error conditions. The experiments included random errors from transport and limited precision of the sensors, as well as systematic biases arising from background concentration errors and limited sensor accuracy. Networks were evaluated by their ability to recover assumed true emissions from incorrect prior assumptions using simulated measurements in a Bayesian inversion framework. The results show that thoroughly investigating network designs using OSSEs prior to physical deployment enables identification of optimal sensor locations that substantially improve emission estimates compared to random placement. Across all tested error cases, we found mid- and high-cost sensors to provide reliable constraints on total city emissions, but mid-cost sensors can introduce biases on sub-urban scales. Sensors with accuracies of 5 ppm or worse produced considerably smaller improvements or even degraded prior emission estimates. Spatially uniform background errors could generally be corrected through an appropriate choice of state vector, whereas spatially varying biases propagated into the inferred emission patterns. These findings were consistent across both cities, suggesting their applicability to similar urban areas. This study thereby provides practical guidance for designing cost-effective urban emission monitoring networks and highlights the importance of assessing diverse error contributions within a network’s planning phase.
Marine Carbon Dioxide Removal (mCDR) approaches are increasingly considered for climate change mitigation as a supplement to rapid emissions reduction. However, it is still unclear if mCDR approaches could be effective, safe, and accountable. A critical requirement for mCDR to work, potentially, is robust monitoring, reporting, and verification (MRV) of greenhouse gas(es) removed through mCDR activities. MRV frameworks and protocols are currently developed in a scattered manner by individual stakeholders, so that the principles they are built upon may or may not appeal to the broader international community that is interested in the ocean commons. International agreement and consolidation on MRV for mCDR seem crucial to legitimize and validate mCDR, considering that the ocean is a globally interconnected fluid and that activities by some may affect many others. Here, we undertake a step toward consolidation of MRV by consulting the international scientific community. We established a global network of scientists organized into 6 "continental" nodes, each of which addressed the same set of MRV-related questions and whose thoughts were equally weighted in the synthesis. Our consultation shows that while there are many converging views on MRV (e.g., the importance of modeling for MRV), there are also differences in the regional MRV priorities (e.g., the importance of regional vs global models). The areas of consensus and divergence identified herein may be instrumental in the design of more widely accepted MRV frameworks, informed equally by scientists from 6 continents.
