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Abstract This article reviews the current status of research on urban green and blue infrastructure (GBI) in developing countries. We critically analyzed a total of 283 papers addressing urban GBI in selected developing countries in Africa, Asia, Latin America and the Caribbean (LAC), published between 2015 and 2019. The review aimed to a) analyze publication trends and typologies of urban GBI; b) identify innovative problem-solving measures using urban GBI, and c) understand priorities, differences and similarities in the deployment of urban GBI between the regions. The article identifies a growing interest in the urban GBI concept in the Global South, with a focus on local sustainable development. Urban GBI aims to address issues of urban greenery, land use policies, food security and poverty alleviation. There is a large variation in the number of articles across regions, with Asia, and particularly China, as the subject having a much larger number of publications when compared to LAC and Africa. We found that the focus of research topics varied between regions, reflecting regional development needs, so that urban agriculture research predominated in Africa, and green spaces and parks in Asia and LAC. GBI is still not implemented as a low-impact development or innovative strategy, except in China, where researchers have examined several cases of systemic GBI use for addressing urban issues. More recently, studies began exploring the linkages between nature and cities in light of global environmental issues such as biodiversity loss and climate change. We conclude with recommendations to further examine empirical evidence of urban GBI deployment and its outcomes in the Global South, that could contribute toward conceptualizing natural resource management in a multi-scalar, multi-dimensional, and multidisciplinary framework.

A pilot-scale UASB-Settler-Digester (USD) system was utilized to treat raw municipal wastewater collected from a sewer system at 10 °C. During the reactor operation, UASB sludge was continuously transferred from the UASB to a settler; concentrated sludge in the settler was then transferred to a digester operated at 35 °C. The results showed that the settler with a hydraulic retention time (HRT) of 3 h increased UASB sludge chemical oxygen demand (COD) concentration from 14.5 ± 2.5 g/L to 29.9 ± 4.1 g/L. With an HRT of 6 h, the USD system achieved a mean COD removal of 49.2%; and 23.9% influent COD was converted to methane. The specific methanogenic activities at 35 °C of the UASB and the digester sludge were 0.26 and 0.24 g CH4 COD/(g VSS d), respectively, and the stability values were 0.21 and 0.16 g CH4 COD/g COD, respectively. The stability of the settled sludge was similar to that of the recirculated UASB sludge. Compared to a UASB-digester system, the system with an added settler achieved similar COD removal and methane production, but reduced sludge recirculation rate (from 16% to 8% of the influent flow rate), which led to a 50% heating energy saving in the digester of the UASB-digester.

Biodiversity conservation policies focus on securing the survival of species and habitats according to their current distribution. This basic premise may be inappropriate for halting biodiversity decline under the dynamic changes caused by climate change. This study explores a dynamic spatial conservation prioritization problem where climate change gradually changes the future habitat suitability of a site' current species. This has implications for survival probability, as well as for species that potentially immigrate to the site. The problem is explored using a set of heuristics for both of two policy objectives focusing on (1) the protection on current (native) species, and (2) all species, including immigrating species. The trade-offs between the protection of native species versus all species is illustrated. The study shows that the development of prediction models of future species distributions as the basis of decision rules can be crucial for ensuring the effectiveness of conservation plans. Finally, it is discussed how more adaptive strategies, that allow for the redirection of resources from protected sites to privately-owned sites, may increase the effectiveness of the conservation networks. Climate change induced shifts in the suitability of habitats for species may increase the value of such adaptive strategies, the benefit decreasing with increasing migration probabilities and species distribution dynamics. © 2011 Elsevier Ltd.

Earth's wilderness areas are reservoirs of genetic information and carbon storage systems, and are vital to reducing extinction risks. Retaining the conservation value of these areas is fundamental to achieving global biodiversity conservation goals; however, climate and land-use risk can undermine their ability to provide these functions. The extent to which wilderness areas are likely to be impacted by these drivers has not previously been quantified. Using climate and land-use change during baseline (1971-2005) and future (2016-2050) periods, we estimate that these stressors within wilderness areas will increase by ca. 60% and 39%, respectively, under a scenario of high emission and land-use change (SSP5-RCP8.5). Nearly half (49%) of all wilderness areas could experience substantial climate change by 2050 under this scenario, potentially limiting their capacity to shelter biodiversity. Notable climate (>5 km year-1) and land-use (>0.25 km year-1) changes are expected to occur more rapidly in the unprotected wilderness, including the edges of the Amazonian wilderness, Northern Russia, and Central Africa, which support unique assemblages of species and are critical for the preservation of biodiversity. However, an alternative scenario of sustainable development (SSP1-RCP2.6) would attenuate the projected climate velocity and land-use instability by 54% and 6%, respectively. Mitigating greenhouse gas emissions and preserving the remaining intact natural ecosystems can help fortify these bastions of biodiversity.

Abstract The unprecedented surge in urbanization and population growth rates is generating multiple impacts, affecting food, energy and water (FEW hereafter) demands. Moreover, the adverse effects are extending to climate, as well as to human and ecosystem health. Coordinated efforts are often deemed critical to minimize the trade-offs while maximizing the synergies in the use and the effective analysis of the interlinkages among food, energy, and water within urban ecosystems. Data are collected and transformed into useful information through different indicators, which are often applied to guide several policies in the urban domain. However, their different nature now asks for a critical reanalysis to collate them into different groups, understanding their guiding principles and identifying possible gaps for further policy- and design-oriented studies. This paper reviews the state-of-the-art on existing urban FEW nexus indicators. Indicators were found to belong to four main distinct groups, measuring resource fluxes (52%); quantifying environmental impacts (13%), and efficiency aspects (29%). Results highlight a need to develop new indicators, considering the inclusion of all involved factors within new integrated metrics. However, prior to developing an overall sustainability indicator system is presented, it would be vital to incorporate as many flows as possible to represent the entire urban systems.

Pollutant emissions from residential heating systems represent a main concern in terms of outdoor air quality. Differently from other pollutants, sub-micron particle emission from heating systems has not yet been exhaustively characterized by the scientific literature, with limited data available, in particular, for gas-fueled boilers. In the present paper, an experimental campaign to measure the sub-micron particle number concentrations and distributions at the stack of different automatically-fed small-scale heating systems (conventional and condensing boilers fueled by natural gas and liquid petroleum gas, and pellet stoves) was performed. Based on the measured concentrations, corresponding emission rates and emission factors were also estimated. The results of the experimental campaign revealed that the highest concentrations were measured for pellet stoves (median value >107 part. m-3), whereas conventional (about 1 × 106 part. m-3) and condensing boilers (<106 part. m-3) presented much lower concentrations. No effect of the fuel (natural gas, liquid petroleum gas) on the total concentration measured at the stack of boilers was recognized, whereas a smaller distribution mode (at 10 nm) was measured for gas-fired boilers. Because of the particle concentration values, the highest particle emission rates and factors were the pellet stove ones (median values of 2.1 × 1015 part. h-1 and 8.4 × 1013 part. kWh-1, respectively), whereas emission rates for conventional and condensing boilers were about 5 × 1013 part. h-1 and 2 × 1013 part. h-1, respectively. The estimated emission factors were also adopted to perform a simplified evaluation of the relative contributions of the investigated automatically-fed small-scale heating systems in terms of particle number on a national scale (Italy): we obtained that the pellet stove contribution is the main one as it accounts for 87% of total emissions of particle number for heating purpose.

A model shows that REDD (reducing emissions from deforestation and degradation) can be extended to biodiversity conservation.

International conservation organisations have identified priority areas for biodiversity conservation. These global-scale prioritisations affect the distribution of funds for conservation interventions. As each organisation has a different focus, each prioritisation scheme is determined by different decision criteria and the resultant priority areas vary considerably. However, little is known about how the priority areas will respond to the impacts of climate change. In this paper, we examined the robustness of eight global-scale prioritisations to climate change under various climate predictions from seven global circulation models. We developed a novel metric of the climate stability for 803 ecoregions based on a recently introduced method to estimate the overlap of climate envelopes. The relationships between the decision criteria and the robustness of the global prioritisation schemes were statistically examined. We found that decision criteria related to level of endemism and landscape fragmentation were strongly correlated with areas predicted to be robust to a changing climate. Hence, policies that prioritise intact areas due to the likely cost efficiency, and assumptions related to the potential to mitigate the impacts of climate change, require further examination. Our findings will help determine where additional management is required to enable biodiversity to adapt to the impacts of climate change.