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Migration, from rural to urban settings is a common phenomenon in Latin America, due to social, economic, political, and other factors. Young people in search of economic and educational opportunities, financial, and social stability, have been migrating to larger urban centers, thus crafting important shifts in rural labor, generational transfer, and domestic economies. Through a systematic literature review of scientific literature, and documents from public institutions and international organizations, published between 2012 and 2022, this article addresses rural-urban migration of youth in Colombia and Guatemala's cattle sector, particularly identifying (i) driving factors, (ii) their impacts on cattle farming, and (iii) public policies implemented to counteract prejudicial effects. Results show that unemployment, lack of educational opportunities, and insecurity are the main reasons for youth migration to cities or abroad, with Mexico, the United States, and Spain being the most common destinations. Additionally, impacts on the cattle sector include shortage of labor and a perfectible generational transfer, hindering the modernization of the industry and investments in climate change adaptation and mitigation strategies. Despite various implemented public policies, the results are partial, and the issue of accelerated youth migration remains relevant. Consequently, without more effective measures adopted by national governments, the cattle sector will lag behind its regional and international competitors, deterring the achievement of the Sustainable Development Goals. As the main contribution of the study, the analysis of migration is highlighted based on its effects on a specific economic sector and not focused on its causes, as evidenced in a wide range of literature.

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Diet shift is an opportunity to mitigate the impacts of food systems, which are responsible for about a third of greenhouse gas (GHG) emissions globally and exert various environmental pressures on ecosystems. This study evaluates the mitigation potential of both global and local environmental impacts through dietary changes within the Brazilian context. Furthermore, the study aims to identify the potential benefits and trade-offs that may arise from these dietary transitions, thus providing a comprehensive analysis of the overall environmental implications. To this end, a life cycle assessment (LCA) was performed to evaluate the environmental impacts of a conventional diet in Brazil and seven alternatives, namely adjusted-EAT-Lancet, pescatarian, vegetarian, entomophagic (insect-based food), mycoprotein (microbial-based food), and synthetic (cell-based food) diets. Results indicate a substantial mitigation potential for GHG emissions (4-9 kg CO2e/cap/day) (39 % to 86 %) and land use (4-9 m2/cap/day) (38 % to 82 %) through a diet shift from a conventional diet to any of the seven alternative diets. However, certain trade-offs exist. A diet shift demonstrates no mitigation potential of soil acidification, and opportunities to reduce water eutrophication (0.02-0.2 g Pe/cap/day) (2 % to 24 %) and water consumption (0.2-0.5 m3/cap/day) (7 % to 14 %) were only found by completely substituting animal products for insect-based food, microbial-based food, and cell-based food. This study highlights the considerable potential of dietary changes to mitigate global environmental impacts associated with food systems. By revealing opportunities and challenges, this study supports science-based decision-making and guides efforts toward sustainable and environmentally friendly food consumption patterns.

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A critical question is whether agroecology can promote climate change mitigation and adaptation outcomes without compromising food security. We assessed the outcomes of smallholder agricultural systems and practices in low- and middle-income countries (LMICs) against 35 mitigation, adaptation, and yield indicators by reviewing 50 articles with 77 cases of agroecological treatments relative to a baseline of conventional practices. Crop yields were higher for 63% of cases reporting yields. Crop diversity, income diversity, net income, reduced income variability, nutrient regulation, and reduced pest infestation, indicators of adaptative capacity, were associated with 70% or more of cases. Limited information on climate change mitigation, such as greenhouse gas emissions and carbon sequestration impacts, was available. Overall, the evidence indicates that use of organic nutrient sources, diversifying systems with legumes and integrated pest management lead to climate change adaptation in multiple contexts. Landscape mosaics, biological control (e.g., enhancement of beneficial organisms) and field sanitation measures do not yet have sufficient evidence based on this review. Widespread adoption of agroecological practices and system transformations shows promise to contribute to climate change services and food security in LMICs. Gaps in adaptation and mitigation strategies and areas for policy and research interventions are finally discussed.

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Second-growth forests (SGF) are critical components for limiting biodiversity loss and climate change mitigation. However, these forests were established after anthropic disturbances such as land use for planting, and in highly human-modified landscapes. These interventions can decrease the ability of biological communities to recover naturally, and it is necessary to understand how multiple drivers, from local scale to landscape scale influence the diversity and carbon stock of these forests in natural regeneration. For this, we used data from 37 SGF growing on areas previously used for eucalyptus plantations in the Brazilian Atlantic Forest, after the last cut cycle. For each SGF, the forest tree species diversity was calculated based on the Hills number, and we also calculated the above-ground carbon stock. Then, we evaluated the influence of multiple environmental factors on these indexes: soil properties, past-management intensity, patch configuration, and landscape composition. Little influence of soil properties was found, only soil fertility negatively influenced above-ground carbon stock. However, past-management intensity negatively influenced tree species diversity and carbon stock. The isolation of other forests and tree species propagules source distance (>500 ha) also negatively influenced the diversity of species. This is probably due to the favoring of tree pioneer species in highly human-modified landscapes because they are more tolerant of environmental changes, less dependent on animal dispersal, and have low carbon stock capacity. Thus, areas with higher past-management intensity and more isolated areas are less effective for passive restoration and may require intervention to recover tree diversity and carbon stock in the Atlantic Forest. The approach, which had not yet been applied in the Atlantic Forest, brought similar results to that found in other forests, and serves as a theoretical basis for choosing priority areas for passive restoration in the biome.

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While the Global North is historically responsible for the majority of greenhouse gas emissions in the atmosphere, Newly Industrializing Countries (NICs) are expected to overtake developed country emissions in the coming years. At the same time, NICs are climbing the ladder of the global economy, increasing their competitiveness on the global stage and catching up with technological competencies of developed economies. Against this background, this paper explores innovation and collaboration in Climate Change Mitigation Technologies (CCMTs) in NICs. The research question is whether the propensity to innovate and diffuse CCMTs is impacted by technological collaboration with two highly developed countries, Germany and The United States. The sample of NICs includes the BRICS (Brazil, Russia, India, China, South Africa) plus Israel, Mexico, and Turkey, in a panel from 1995 to 2015. The empirical results suggest that collaboration with both Germany and the U.S. is highly significant for domestic CCMT innovation in NICs. These findings are important because, stepping beyond the literature on the merits and drawbacks of global climate governance tools such as the Clean Development Mechanism (CDM) and related UNFCCC processes, they show that collaboration for climate and environmental technologies could become a key tool to significantly improve the chances to stay in line with the Paris Climate Agreement. Finally, the policy advice for NICs and developing countries is to, above all else, focus on incubating strong technological innovation systems, including strengthening domestic Intellectual Property Rights (IPR), as well as to enhance technological collaboration with developed countries.

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Methane (CH4) emissions from enteric fermentation in cattle are an important source of greenhouse gases, accounting for about 40% of all agricultural emissions. Diet quality plays a fundamental role in determining the magnitude of CH4 emissions. Specifically, the inclusion of feeds with high digestibility and nutritional value have been reported to be a viable option for reducing CH4 emissions and, simultaneously, increase animal productivity. The present study aimed to evaluate the effect of the nutritional composition and voluntary intake of diets based on tropical forages upon CH4 emissions from zebu steers. Five treatments (diets) were evaluated: Cay1: Urochloa hybrid cv. Cayman (harvested after 65 days of regrowth: low quality); Cay2: cv. Cayman harvested after 45 days of regrowth; CayLl: cv. Cayman + Leucaena leucocephala; CayLd: cv. Cayman + Leucaena diversifolia; Hay: Dichantium aristatum hay as a comparator of common naturalized pasture. For each diet representing different levels of intensification (naturalized pasture, improved pasture, and silvopastoral systems), CH4 emissions were measured using the polytunnel technique with four zebu steers housed in individual chambers. The CH4 accumulated was monitored using an infrared multigas analyzer, and the voluntary forage intake of each animal was calculated. Dry matter intake (DMI, % of body weight) ranged between 0.77 and 2.94 among diets offered. Emissions of CH4 per kg of DMI were significantly higher (P < 0.0001) in Cay1 (60.4 g), compared to other treatments. Diets that included Leucaena forage legumes had generally higher crude protein contents and higher DMI. Cay1 and Hay which had low protein content and digestibility had a higher CH4 emission intensity (per unit live weight gain) compared to Cay2, CayLl and CayLd. Our results suggest that grass consumed after a regrowth period of 45 days results in lower CH4 emissions intensities compared to those observed following a regrowth period of 65 days. Diets with Leucaena inclusion showed advantages in nutrient intake that are reflected in greater live weight gains of cattle. Consequently, the intensity of the emissions generated in the legume-based systems were lower suggesting that they are a good option for achieving the emission reduction goals of sustainable tropical cattle production.

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The Paris Agreement and the United Nations Framework Convention on Climate Change outline mitigation goals by sector. However, this framing is likely to create climate justice issues as it does not explicitly address the contributions of individuals. High emissions from luxury activities like commercial air travel are addressed with voluntary and behavioral change approaches for mitigation while the global rural communities who are dependent on forestry-based livelihoods face carbon credit schemes as well as federal and international conservation interventions despite having a lower per capita carbon footprint. To illustrate this point, the emissions of the average air traveler and several international flights are compared to the average forest user in relation to land use change emissions. In many cases, a single round-trip international flight emits more CO2 per person than the yearly national average of India, Mexico, and Tanzania; all countries with important forestry sectors and indigenous people that depend on forestry-based livelihoods. The disproportionate regulatory burden of forest users in the developing world contrasts their relative contribution to climate change and the unregulated individual behaviors of the global elite. It is time for mandatory offset charges on airline tickets and regulatory framing of mitigation by per capita contributions instead of sector-based approaches.

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Resumen Los sistemas agroforestales diversos concilian la producción de alimentos, la conservación de la biodiversidad y la provisión de servicios ecosistémicos como el secuestro de carbono atmosférico. Sin embargo, el papel de la riqueza florística sobre la producción de carbono en la biomasa de estos sistemas no está claro. Este estudio evaluó el efecto de la riqueza de especies y la estructura de la vegetación sobre el carbono en la biomasa de diferentes sistemas agroforestales, en la Amazonía Sur de Bolivia. Para eso, fueron estudiados 25 sistemas agroforestales y 4 bosques secundarios, en los departamentos de Santa Cruz y Beni. En cada sistema se instalaron parcelas circulares de 1 963 m2, donde la vegetación (árboles, arbustos y herbáceas) y necromasa (hojarasca, ramas y árboles muertos) fueron muestreados. Se utilizó funciones lineales y logarítmicas para evaluar el efecto de la riqueza y estructura de la vegetación sobre el carbono; y la partición de la varianza para examinar el efecto puro y compartido de las variables riqueza y estructura. Las regresiones mostraron una relación positiva fuerte de la riqueza de especies sobre el carbono de la biomasa (r2 = 0.74; P < 0.001). En la partición de la varianza, el 85.7 % de la variabilidad del carbono fue explicada por la riqueza, estructura y variación de la estructura. De forma aislada, la riqueza explicó el 12.7 %, la estructura el 8.8 % y la variación de la estructura el 4.8 %. Estos resultados confirman que el carbono en la biomasa sobre el suelo aumenta con la riqueza de especies y la variación estructural de la vegetación. Por lo tanto, sistemas agroforestales más biodiversos y estratificados son más eficientes en el uso de los recursos y pueden contribuir con la mitigación del cambio climático.(AU)

Abstract Diverse agroforestry systems conciliate food production, biodiversity conservation, and the provision of ecosystem services as atmospheric carbon sequestration. However, the role of floristic richness in the production of biomass in these systems is not clear. This study evaluated the effect of species richness and vegetation structure on aboveground biomass carbon in different agroforestry systems in the Southern Amazon of Bolivia. For that, 25 agroforestry systems and 4 secondary forests were studied in the departments of Santa Cruz and Beni. In each system, a 1 963 m2 circular plot was installed, where the vegetation (trees, shrubs and herbaceous) and necromass (leaf litter, branches and dead trees) were sampled. Linear and logarithmic functions were used to evaluate the effect of vegetation richness and structure on carbon, and the variance partition was used to examine the pure and shared effect of the richness and vegetation structure variables on carbon. Regressions showed a positive strong relationship between species richness and carbon (r2 = 0.74; P < 0.001). The partition of carbon variance showed that richness, structure and variation of the structure explained 85.7 %. Alone the richness explained 12.7 %, the structure 8.8 % and the variation of the structure 4.8 %. These results confirm that carbon in the aboveground biomass increases with species richness and structural variation of the vegetation. Therefore, more biodiverse and stratified agroforestry systems are more efficient in the use of resources and can contribute to climate change mitigation.(AU)

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Urban environments in Latin America must begin decarbonizing their activities to avoid increasing greenhouse gases (GHGs) emissions rates due to their reliance on fossil fuel-based energy to support economic growth. In this context, cities in Latin America have high potential to convert sunlight into energy. Hence, the main objective of this study was to determine the potential of electricity self-sufficiency production and mitigation of GHG emissions in three medium-sized cities in Peru through the revalorization of underutilized rooftop areas in urban environments. Each city represented a distinct natural area of Peru: Pacific coast, Andean region and Amazon basin. More specifically, photovoltaic solar systems were the technology selected for implementation in these rooftop areas. Data on incident solar energy, temperature and energy consumption were collected. Thereafter, ArcGis10.3 was used to quantify the total usable area in the cities. A series of correction factors, including tilt, orientation or roof profiles were applied to attain an accurate value of usable area. Finally, Life Cycle Assessment was the methodology chosen to calculate the reduction of environmental impacts as compared to the current context of using electricity from the regional grids. Results showed that the cities assessed have the potential to obtain their entire current electricity demand for residential, commercial and public lighting purposes, augmenting energy security and resilience to intermittent natural disasters, with the support of decentralized storage systems. This approach would also translate into substantial reductions in terms of GHG emissions. Annual reductions in GHG emissions ranged from 112ton CO2eq in the city of Ayacucho to over 523kton CO2eq in Pucallpa, showing that cities in the Amazon basin would be the ones that benefit the most in terms of climate change mitigation.

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This study examines a pathway for building urban climate change mitigation policies by presenting a multi-dimensional and transdisciplinary approach in which technical, economic, environmental, social, and political dimensions interact. Now, more than ever, the gap between science and policymaking needs to be bridged; this will enable judicious choices to be made in regarding energy and climate change mitigation strategies, leading to positive social impacts, in particular for the populations at-risk at the local level. Through a case study in Juarez, Chihuahua, Mexico, we propose a multidimensional and transdisciplinary approach with the role of scientist as policy advisers to improve the role of science in decision-making on mitigation policies at the local level in Mexico.

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Agroforestry systems have substantial potential to conserve native biodiversity and provide ecosystem services. In particular, agroforestry systems have the potential to conserve native tree diversity and sequester carbon for climate change mitigation. However, little research has been conducted on the temporal stability of species diversity and aboveground carbon stocks in these systems or the relation between species diversity and aboveground carbon sequestration. We measured changes in shade-tree diversity and shade-tree carbon stocks in 14 plots of a 35-ha coffee cooperative over 9 years and analyzed relations between species diversity and carbon sequestration. Carbon sequestration was positively correlated with initial species richness of shade trees. Species diversity of shade trees did not change significantly over the study period, but carbon stocks increased due to tree growth. Our results show a potential for carbon sequestration and long-term biodiversity conservation in smallholder coffee agroforestry systems and illustrate the opportunity for synergies between biodiversity conservation and climate change mitigation.

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