The concept of planetary boundaries and Earth System Boundaries serves as a potent framework for understanding various environmental limits. Breaches at any single or combination of levels can result in significant environmental and societal impacts. Rapid urbanisation is often cited as a key contributor to the disruption of planetary boundaries; however, scholarly explorations of multi-modal impact assessment are scarce. Policies that alienate urbanisation or treat it as an isolated phenomenon are not wise. Integrated roadmaps involving all the stakeholders at the societal and governmental levels are the need of the hour. This study qualitatively analyzes the importance of urban wetlands in mitigating the transgression of planetary boundaries, synthesizing existing literature, secondary data, and expert insights. East Kolkata Wetlands (EKW), an urban Ramsar site, is used as a case study to illustrate these dynamics. The interrelations between the quality of life of the migrating population in the metropolitan city of Kolkata, undergoing aggressive urbanisation and the overall health of the EKW underscore the criticality of strategic socio-economic management of population dynamics for efficient protection and restoration of environmental resources. A SWOT analysis was performed, taking into consideration the intricacies of carbon, nutrient and pollutant cycling in EKW for their potential role in the maintenance and protection of biodiversity. A ten-point inclusive strategy is proposed for affirmative actions to protect urban wetlands and utilise them as a key tool in mitigating the disruption of planetary boundaries due to rapid urbanisation. Adequate funding and monitored expenditure management need to be mandated by policy to attain the sustainability of the urban wetlands.

Mangrove ecosystems play a pivotal role in global carbon storage, biodiversity maintenance, and coastal resilience, yet research remains fragmented, often isolating these functions rather than examining their interconnections. Critical gaps persist regarding spatial variability in carbon stocks, the functional role of biodiversity, and the long-term resilience benefits of mangroves under climate change and anthropogenic pressures. This systematic review synthesizes global evidence from 2000 to 2024, integrating carbon dynamics, biodiversity functions, and resilience attributes of mangrove ecosystems. Unlike previous reviews, this study adopts a distinctive mixed-methods framework that integrates quantitative scientometric analysis with qualitative synthesis of carbon sequestration parameters, biodiversity indicators, and vulnerability evaluations. Literature was sourced primarily from Scopus using targeted search strings ("mangrove," "carbon sequestration," "biodiversity," "coastal resilience"), with screening guided by the PRISMA framework. From over 2300 initial records, 1356 peer-reviewed articles were analyzed using Biblioshiny (R package) and VOSviewer to map research trends, collaboration networks, and thematic clusters, revealing an exponential growth in publications post-2015. Results indicate that mangroves sequester carbon at a mean rate of 174 g C m-2 yr-1 (range: 95-235 g C m-2 yr-1), with total carbon stocks reaching up to 1745 Mg C ha-1, surpassing many terrestrial forests. The Pacific and Southeast Asian regions exhibit the highest carbon densities. Mangrove biodiversity, supporting over 2000 species, underpins essential ecological functions including nutrient cycling, soil accretion, and carbon retention. Additionally, mangroves provide coastal protection for more than 150 million people by stabilizing shorelines and reducing erosion. Restoration could recover an estimated 390 million metric tons of CO₂ equivalent, underscoring its potential for climate mitigation. However, accelerating habitat loss, human pressures, and insufficient policy enforcement threaten their sustainability. This synthesis emphasizes the urgent need for integrated, cross-disciplinary conservation frameworks that unite carbon, biodiversity, and resilience perspectives to enhance climate adaptation and inform evidence-based policy.

Abstract Coastal estuaries are hotspots of biogeochemical cycling, biodiversity, and sediment processing, yet the drivers of carbon cycle processes remain poorly constrained. Here, we elucidate the influence of hydrological connectivity on carbon biogeochemistry in the Indian Sundarban over successive monsoon seasons by comparing hydrologically connected channels with perennial freshwater flow to channels isolated from feeding rivers. Results demonstrate dissolved organic carbon (DOC) and particulate organic carbon (POC) varied significantly with both season and connectivity. Dissolved organic carbon peaked pre‐monsoon and POC during the monsoon, with higher concentrations in hydrologically connected sites. Dissolved inorganic carbon (DIC) declined during the monsoon season but showed no connectivity effect. Elevated DOC relative to conservative mixing was attributed to freshwater runoff or groundwater input. Isotope data (δ 13 C) indicated POC respiration dominated during pre‐ and post‐monsoon, while DOC flocculation during the monsoon controlled POC dynamics, particularly in connected sites. Carbonate dissolution primarily regulated pre‐monsoon DIC, while organic matter degradation dominated in the monsoon and post‐monsoon periods. CO 2 efflux, measured across all sites, was consistently a source to the atmosphere and two to four times higher in connected channels, with higher turbulence driving maximum fluxes. Our findings demonstrate that hydrological connectivity fundamentally structures estuarine carbon cycling, lowering organic carbon concentrations and enhancing CO 2 fluxes. Shifts in global coastal delta sediment dynamics, in association with anthropogenic river management, therefore, have the potential to significantly alter delta carbon dynamics on a global scale.

Blue carbon ecosystems (BCEs) store a significant amount of organic carbon (OC) in their soils, including OC sequestered by other ecosystems and transported into these ecosystems, referred to as allochthonous OC. This study reviews the state-of-the-art knowledge on the abundance and sources (including still unexplored ones) of allochthonous particulate organic carbon (POC) and reviews the ways allochthonous POC is managed under the current blue carbon policy frameworks for carbon benefits accounting in blue carbon restoration and conservation projects. Based on a review of 102 studies, we find that 56 ± 25% of the soil organic carbon (SOC) deposits in BCEs are allochthonous POC, most commonly identified as originating from terrestrial ecosystems, seston and macroalgae. Whether allochthonous POC should be included in blue carbon accounting is a matter of debate among the scientific community, due to the risks of overestimating carbon benefits and double-counting. Consequently, it is often excluded from voluntary carbon markets, but its inclusion can be justified given the role of BCEs in stabilising OC that may otherwise be remineralised. Based on existing knowledge, a deeper understanding of the stability and behaviour of different types of allochthonous POC under varying environmental conditions is needed to assess whether and to what extent these fractions can be counted toward carbon benefits.

This study aims to provide a comprehensive assessment of vulnerability and risk to populations and critical infrastructure along the Andaman coast of Thailand, an area highly susceptible to coastal hazards. We combined the Integrated Valuation of Ecosystem Services and Trade-Offs (InVEST) Coastal Vulnerability Model (CVM) and the Digital Shoreline Assessment System (DSAS), further utilising an Artificial Neural Network (ANN) to integrate and analyse diverse variables. The analysis considered shoreline change rates, erosion-accretion dynamics, regional sea-level rise projections, flooding and inundation patterns, tsunami surge probabilities, cyclone trajectories, and socioeconomic factors, including population density and the distribution of critical infrastructure. InVEST CVM incorporated indices such as wave exposure, geomorphology, and natural habitats, while DSAS provided long-term shoreline change data. Vulnerability was quantified by integrating model outputs into the ANN, accounting for exposure, hazard, sensitivity, and adaptive capacity. Risk was calculated by combining vulnerability with the spatial distribution of population and infrastructure. Results reveal that approximately 35% of the coastline is classified as highly vulnerable (particularly the outward-facing shores in Phang Nga, Ranong, Krabi, and Satun), with erosion rates exceeding-9.8 m per year in certain zones. In contrast, the highest risk is concentrated in densely populated areas, particularly Phuket, having risk scores above 0.8 (on a scale of 0 to 1). Less-populated but highly vulnerable regions could become high-risk zones in the future due to development. The study underscores the importance of early, targeted interventions and integrated planning to strengthen the resilience of Thailand's Andaman coastline amid growing climate-related hazards.

The outbreak of the COVID-19 pandemic wreaked havoc across the globe. Like many nations, India imposed lockdowns to restrict virus transmission. The present study focused on the air quality changes in Mumbai during three pandemic surges, 1st (25 March-14 April 2020), 2nd (22 April-1 May 2021), and 3rd (10 January-19 January 2022). This study also considered the effect of meteorology on air pollution levels. The pollutants, PM2.5, PM10, CO, NH3, SO2, NO2, O3, and air quality index (AQI) data acquired from Central Pollution Control Board (CPCB), India, were analyzed in this study. The concentrations of NH3, SO2, NO2, and O3 always remained below the standards of CPCB. CO is the only pollutant that was consistently higher than the prescribed standard. PM2.5 & PM10 (principal pollutants) were below the standard during 1st wave. The recent two waves showed mixed results. PM2.5, PM10, CO, NH3, SO2, NO2 and AQI increased by 56%, 45%, 40%, 52%, 60%, 44%, and 38%, respectively, in 2nd wave compared to 1st wave. Likewise, 89%, 15%, 43%, 5%, 84%, 44% and 49% rise was observed for PM2.5, PM10, CO, SO2, NO2, O3 and AQI, respectively, except for NH3, in 3rd wave compared to 2nd wave. This study recorded a remarkable improvement in pollutant concentrations for 1st and 3rd wave lockdowns in comparison to the same periods of the non-pandemic year (2019), except for SO2 in the 1st wave. The 2nd wave noted mixed results. All the pollutants were positively correlated, having high to moderate significant relationships. The degree of strictness in imposing lockdowns and seasonal meteorological variability regulated the pollution levels. Policymakers, planners, and decision-makers must find a new tactic to refresh the city's air pollution level by implementing occasional short-term lockdowns. Such practices would assist us in achieving a few sustainable development goals by 2030.

Particulate matter (PM2.5) has long been recognized as a lethal air pollutant. Multifarious anthropogenic activities, especially in the urbanized belts, lead to this pollution, and the humans and other life forms thriving in these regions suffer the worst. In this regard, the present study collated the PM2.5 data for seven years (2017–2023) across 760 cities, encompassing three neighbouring countries, China, India, and Pakistan, that comprise more than 38

The present study reports on a transient diatom bloom of Palmerina hardmaniana (Greville) Hasle 1996 encountered accidentally in May 2018 in the world's largest mangrove forest of Sundarbans, India. This bloom was the sixth record of diatom blooms from Indian coastal waters and the fourth from Sundarbans waters. The diatom cell count ranged from 2.571 x 10(4) to 6.857 x 10(4) cells L-1 during the bloom. The zooplankton taxa count decreased from 39 during the pre-bloom to 30 during bloom and 31 during the post-bloom phase. However, no significant (p < 0.05) change in zooplankton species richness was observed between the three different phases. The consistent occurrence of copepod Bestiolina simlis across sampling points indicated a high tolerance to environmental parameters. The zooplankton population also did not respond vehemently to bloomforming P. hardmaniana in this creek environment. These observations warrant further studies to examine the effect of blooms on the overall marine ecological food chain of creek ecosystems.

Blue carbon cycling in mangrove ecosystems is proving to be more complex than previously thought. The objective of this study was the application of structural equation modelling (SEM) to capture such complex and varying data types and provide a holistic understanding of mangrove blue carbon cycling using data from the Indian Sundarban as a test case. We found that SEM was effective at integrating multiple data types and characterizing the processes and variables that regulate the nature and magnitude of CO2 fluxes within a mangrove ecosystem, including atmosphere-hydrosphere, atmosphere-pedosphere, and net ecosystem exchange. Overall, this study finds that atmospheric, water, and soil temperatures were the main and common drivers of CO2 effluxes towards the atmosphere from the entire ecosystem, waterbodies, and soils of mangrove ecosystems, respectively. We conclude that SEM is useful for combining data from different sources, gaining an overarching view of the complex biogeochemical cycling of the blue carbon ecosystems.

Constant monitoring of the mangroves is important for understanding their health species assemblage and undertaking policies to rehabilitate or restore them. In this study, an attempt was made to classify and detect health and carbon stock in mangroves through a Remote Sensing perspective. The AVIRIS-NG dataset with high spectral (5 nm) and spatial (5 m) resolution proved to be capable of identifying different species of the same mangrove genus along with other morphological features. Using Spectral Angle Mapper (SAM) classification technique, 75% accuracy has been achieved over 12 separate classes. The health of the Lothian Island mangroves was evaluated by using eight different vegetation indices, namely ACI, ARI, MARI, ARVI, CAI, CARI, Chl-red-edge, and REPI. The vegetation indices were normalized and then used as input in a Multi-Criteria Decision Support System (MCDSS) model. The MCDSS model output health map clearly identifies the degraded and healthy mangroves on Lothian Island. The Lothian Island mangroves were found to be degraded in most of the region, which should be of major concern. Above Ground Biomass (AGB), which is another indicator of health, was calculated using Field measured data and AVIRIS-NG hyperspectral data. The highest, lowest, and mean biomass recorded in field transact is 507.19 and 7.39 and 126.43 tonnes, respectively. These three parameters, namely species assemblage of mangroves, their health, and AGB combined can provide much insight into the ecosystem health of Lothian Island. (c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

The study characterized the temporal and spatial variability in greenhouse gas (GHG) fluxes (CO2, CH4, and N2O) between December 2020 and November 2021 and their regulating drivers in the subtropical wetland of the Indian Himalayan foothill. Five distinct habitats (M1—sloppy surface at swamp forest, M2—plain surface at swamp forest, M3—swamp surface with small grasses, M4—marshy land with dense macrophytes, and M5—marshy land with sparse macrophytes) were studied. We conducted in situ measurements of GHG fluxes, microclimate (AT, ST, and SMC(v/v)), and soil properties (pH, EC, N, P, K, and SOC) in triplicates in all the habitat types. Across the habitats, CO2, CH4, and N2O fluxes ranged from 125 to 536 mg m−2 h−1, 0.32 to 28.4 mg m−2 h−1, and 0.16 to 3.14 mg m−2 h−1, respectively. The habitats (M3 and M5) exhibited higher GHG fluxes than the others. The CH4 flux followed the summer > autumn > spring > winter hierarchy. However, CO2 and N2O fluxes followed the summer > spring > autumn > winter. CO2 fluxes were primarily governed by ST and SOC. However, CH4 and N2O fluxes were mainly regulated by ST and SMC(v/v) across the habitats. In the case of N2O fluxes, soil P and EC also played a crucial role across the habitats. AT was a universal driver controlling all GHG fluxes across the habitats. The results emphasize that long-term GHG flux monitoring in sub-tropical Himalayan Wetlands has become imperative to accurately predict the near-future GHG fluxes and their changing nature with the ongoing climate change.

This study characterized India's Kolkata and Howrah Municipal Corporations' air quality during three prominent waves of the coronavirus pandemic (25 March–14 April 2020; 15 May–30 May 2021; and 1 January–15 January 2022). The primary aim was to examine the role of these COVID-19 pandemic-induced lockdowns and their stringency and meteorological factors in governing the pollutant concentrations, namely, CO, NH3, NO2, O3, PM10, PM2.5, SO2, and monitored by ten automated air pollution monitoring stations (AAMS) of the Central Pollution Control Board (CPCB). A total of 20 days of pollutant data from ten AAMS across four years were analyzed in this study. CO was above the CPCB standard, while PM2.5 and PM10 varied during all three waves. PM2.5, PM10, NO2, SO2, and O3 levels were − 44

The Sundarban is the world’s largest contiguous mangrove forest and stores around 26.62 Tg of blue carbon. The present study reviewed the factors causing a decline in its blue carbon content and poses a challenge in enhancing the carbon stock of this region. This review emphasized that recurrent tropical cyclones, soil erosion, freshwater scarcity, reduced sediment load into the delta, nutrient deficiency, salt-stress-induced changes in species composition, mangrove clearing, and anthropogenic pollution are the fundamental drivers which can potentially reduce the total blue carbon stock of this region. The southern end of the Ganges–Brahmaputra–Meghna Delta that shelters this forest has stopped its natural progradation due to inadequate sediment flow from the upper reaches. Growing population pressure from the north of the Sundarban Biosphere Reserve and severe erosion in the southern end accentuated by regional sea-level rise has left minimal options to enhance the blue carbon stock by extending the forest premises. This study collated the scholarly observations of the past decades from this region, indicating a carbon sequestration potential deterioration. By collecting the existing knowledge base, this review indicated the aspects that require immediate attention to stop this ecosystem’s draining of the valuable carbon sequestered and, at the same time, enhance the carbon stock, if possible. This review provided some key recommendations that can help sustain the blue carbon stock of the Indian Sundarban. This review stressed that characterizing the spatial variability of blue carbon with more sampling points, catering to the damaged trees after tropical cyclones, estuarine rejuvenation in the upper reaches, maintaining species diversity through afforestation programs, arresting coastal erosion through increasing sediment flow, and combating marine pollution have become urgent needs of the hour. The observations synthesized in this study can be helpful for academics, policy managers, and decision makers willing to uphold the sustainability of the blue carbon stock of this crucial ecosystem.

River deltas globally are highly exposed and vulnerable to natural hazards and are often over-exploited landforms. The Global Delta Risk Index (GDRI) was developed to assess multi-hazard risk in river deltas and support decision-making in risk reduction interventions in delta regions. Disasters have significant impacts on the progress towards the Sustainable Development Goals (SDGs). However, despite the strong interlinkage between disaster risk reduction and sustainable development, global frameworks are still developed in isolation and actions to address them are delegated to different institutions. Greater alignment between frameworks would both simplify monitoring progress towards disaster risk reduction and sustainable development and increase capacity to address data gaps in relation to indicator-based assessments for both processes. This research aims at aligning the GDRI indicators with the SDGs and the Sendai Framework for Disaster and Risk Reduction (SFDRR). While the GDRI has a modular indicator library, the most relevant indicators for this research were selected through a delta-specific impact chain designed in consultation with experts, communities and stakeholders in three delta regions: the Red River and Mekong deltas in Vietnam and the Ganges–Brahmaputra–Meghna (GBM) delta in Bangladesh and India. We analyse how effectively the 143 indicators for the GDRI match (or not) the SDG and SFDRR global frameworks. We demonstrate the interconnections of the different drivers of risk to better inform risk management and in turn support delta-level interventions towards improved sustainability and resilience of these Asian mega-deltas.

Abstract Sub-tropic Himalayan wetlands play a critical role in regional greenhouse gas (GHG) fluxes and budgets, consequently influencing climate change. Nevertheless, the magnitude, trends, and drivers regulating GHGs fluxes in the sub-tropic wetlands of the Indian Himalayan foothill remain uncertain. Herein, we characterized temporal and spatial GHGs fluxes (CO2, CH4, and N2O) between December 2020 and November 2021 to identify patterns and regulating drivers in the subtropical wetland of the Indian Himalayan foothill. The wetland was divided into five habitats (M1-sloppy surface at swamp forest; M2-plain surface at swamp forest; M3-swamp surface with small grasses; M4-marshy land with dense macrophytes and M5-marshy land with sparse macrophytes) for in-situ measurement of GHGs fluxes (CO2, CH4, and N2O), microclimate (air and soil temperature, soil moisture), soil properties (pH, EC, N, P, K, and SOC). Across the habitats, CO2, CH4, and N2O fluxes ranged between 125.15 to 536.00 mg m− 2 h− 1, 0.32 to 28.35 mg m− 2 h− 1 and 0.16 to 3.14 mg m− 2 h− 1, respectively. The habitats (M3 and M5) exhibited higher GHGs fluxes (CO2, CH4, and N2O) than counterpart habitats. The highest CO2 fluxes were reported in summer, followed by Spring, Autumn, and Winter. However, higher CH4 and N2O flux in summer, followed by Autumn, Spring, and Winter. The soil temperature and SOC were reported as crucial drivers regulating CO2 fluxes than soil moisture. However, soil temperature and moisture equally regulated CH4 and N2O fluxes across the habitats. N2O fluxes were regulated by soil phosphorus and EC across the habitats. The air temperature was a universal driver controlling all GHGs fluxes across the habitats. We urged that long-term GHG fluxes monitoring and identifying drivers across spatiotemporal scales are required to accurately predict GHGs fluxes and budget to understand the warming potential of GHGs in Indian Himalayan wetlands.

The seasonal and interannual variation in the partial pressure of carbon dioxide in water [pCO 2 (water)] and air-water CO 2 exchange in the Mahanadi estuary situated on the east coast of India was studied between March 2013 and March 2021. The principal aim of the study was to analyze the spatiotemporal variability and future trend of pCO 2 and air-water CO 2 fluxes along with the related carbonate chemistry parameters like water temperature, pH, salinity, nutrients, and total alkalinity, over 9 years. The seasonal CO 2 flux over nine years was also calculated using five worldwide accepted equations. The seasonal map of pCO 2 (water) followed a general trend of being high in monsoon (2628 ± 3484 μatm) associated with high river inflow and low during pre-monsoon (445.6 ± 270.0 μatm). High pCO 2 in water compared to the atmosphere (average 407.6–409.4 μatm) was observed in the estuary throughout the sampling period. The CO 2 efflux computed using different gas transfer velocity formulas was also consistent with pCO 2 water acquiring the peak during monsoon in the Mahanadi estuary (6033 ± 9478 μmol m −2 h −1 ) and trough during pre-monsoon (21.66± 187.2 μmol m −2 h −1 ). The estuary acted as a net source of CO 2 throughout the study period, with significant seasonality in the flux magnitudes. However, CO 2 sequestration via photosynthesis by phytoplankton resulted in lower emission rates toward the atmosphere in summer. This study uses the autoregressive integrated moving average (ARIMA) model to forecast pCO 2 (water) for the future. Using measured and predicted values, our work demonstrated that pCO 2 (water) has an upward trend in the Mahanadi estuary. Our results demonstrate that long-term observations from estuaries should be prioritized to upscale the global carbon budget.

&lt;p&gt;The Indian Sundarban has witnessed consecutive major cyclones (Cyclone Bulbul, Super Cyclone Amphan and Cyclone Yaas) in the 18 months between November 2019 and May 2021. Following Cyclone Yaas, the region also faced an extreme rainfall event. These extreme events have been compounded by the Covid-19 pandemic. This consecutive (and compound) hazard occurrence caused differential impacts based on varying levels of exposures and adaptive capacity of individuals. Examining the adaptive capacity of individuals within the context of consecutive hazards presents an opportunity to understand the ways in which adaptive capacity is drawn upon in disaster preparedness, response, and recovery actions, and how consecutive hazards with reduced return time affect the capacity of adaptive capacity to regenerate, with implications for risk levels. Since climate change is predicted to increase the intensity and frequency of cyclones, understanding where, when and with whom adaptive capacity needs to be supported is essential to reduce disaster risk in the Indian Sundarban delta.&amp;#160;In-depth interviews were conducted with six men and six women of different socio-economic backgrounds from two community development blocks with different levels of exposure to cyclones (Sagar and Gosaba). Using the Local Adaptive Capacity Framework, this study reveals that adaptive capacities differ by gender and socio-economic background.&amp;#160; These different adaptive capacities were manifest in differential natures of preparedness, response, and recovery as undertaken by the respondents &amp;#8211; and thus different levels of impact from cyclone and indirect Covid exposure. The increasing frequency and intensity of cyclones reduced the amount of time for adaptive capacity to replenish itself, hence there is an aggregated erosion of adaptive capacity, meaning that people are less able to absorb the impacts of cyclones that occur in quick succession relative to those that occur with a greater lag time. This study also includes co-produced adaptation measures which the respondents and the authors felt were needed for effective disaster risk reduction. These include structural interventions like raised concrete housing and resilient embankments, ecosystem-based adaptations like mangrove plantation and restoration especially in mudflats of fringe areas, livelihood-based adaptations like cultivation of saline-resistant crops, community based interventions like operation of community kitchens in the aftermath of disasters, importance of evacuation for all residents, and judicious relief distribution, and institutional adaptation including fair compensation. These findings add empirical weight to the concept of adaptation pathways, and highlight how the adaptation options available at any point in time are at least in part contingent on past circumstances. They also highlight the intersectional nature of adaptive capacity, which is important to inform policy and practice that equitably supports capacity to adapt.&amp;#160;&lt;/p&gt;