Our study evaluated the effectiveness of using eight pathways in combination for a complete to transition from fossil fuels to renewable energy by 2050. These pathways included renewable energy development; improving energy efficiency; increasing energy conservation; carbon taxes; more equitable balancing of human wellbeing and per capita energy use; cap and trade systems; carbon capture, utilization, and storage; and nuclear power development. We used the annual ‘British Petroleum statistical review of world energy 2021’ report as our primary database. Globally, fossil fuels, renewable (primarily hydro, wind and solar), nuclear energy accounted for 83%, 12.6%, and 6.3% of the total energy consumption in 2020. To achieve zero fossil fuel use by 2050, we found that renewable energy production will need to be increased by up to 6-fold or 8-fold if energy demand is held constant at, or increased 50% from, the 2020 energy demand level. Constraining 2050 world energy demand to a 25% increase over the 2020 level, improves the probability of achieving independence from fossil fuels. Improvements in energy efficiency need to accelerate beyond the current rate of ~1.5% per year. Aggressive application of energy conservation policies involving land use and taxation could potentially reduce world energy use by 10% or more by 2050. Our meta-analysis shows that the minimum level of per capita energy consumption that would allow 8 billion people to have a ‘Decent Living Standard’ is on average ~70 GJ per capita per year, which is 93% of the 2020 global average. Developed countries in temperate climates with high vehicle-dependency needed ~120 GJ per capita year−1, whereas equatorial countries with low vehicle-dependency needed 30 GJ per capita year−1. Our meta-analyses indicated replacement of fossil fuels with renewable energy by 2050 may be possible but will require aggressive application of all eight pathways, major lifestyle changes in developed countries, and close cooperation among all countries.

Predation by jaguars (Panthera onca) and pumas (Puma concolor) is often a source of conflict with cattle ranching in northeastern Sonora, Mexico. Because jaguars are endangered in Mexico, such conflicts have biological, social, and economic consequences. We documented the extent of predation by jaguars and pumas on cattle in 1999-2004 in northeastern Sonora, where the northernmost breeding population of jaguars exists in North America. Jaguars and pumas killed only calves , 12 mo old, and calves constituted 58% of prey biomass consumed by jaguars and 9% by pumas. Annual cause-specific mortality rates of confirmed jaguar predation (# 0.018), confirmed and suspected jaguar predation (# 0.018), and all confirmed and suspected large felid predation (# 0.018) were low and cattle calf survival was high (0.89-0.98 annually). If calves reported as missing but for which no evidence of mortality could be found were classed as large felid predation, annual cause-specific rates increased to 0.006-0.038. Collectively, confirmed jaguar and puma predation accounted for , 14% (57/408) of total cattle losses, with jaguars responsible for 14% of all calf losses; this could increase to a maximum of 36% (146/408) if missing calves were included in the totals. While jaguar and puma predation may have an impact on some small cattle operations, it is generally minor compared to losses from other causes in northeastern Sonora. Moreover, 91% of all confirmed calf kills were associated with three individual jaguars in our study. Targeting problem cats rather than broad-scale predator control may therefore be a viable alternative to address chronic predation problems. Because most (83%) instances of jaguar predation occurred during the dry season along thick riparian habitats, modified cattle husbandry operations, such as establishment of permanent water sources in uplands and away from dense vegetative cover, could ameliorate many cases of predation by jaguars on cattle. Resumen La predación por jaguares y pumas es a menudo fuente de conflicto con ganaderos en el Noreste de Sonora, México. Debido a que los jaguares están en peligro de extinción en México tales conflictos tienen repercusiones biológicas, sociales y económicas. Documentamos el grado de depredación en ganado por jaguares y pumas de 1999 al 2004 en el noroeste de Sonora, donde existe la población reproductiva de jaguares localizada más al norte en la región de Norte Ame´rica. Los jaguares y pumas matan becerros de menos de 12 meses de edad, y los becerros constituyen el 57% de la biomasa de las presas consumidas por jaguares y 9% por pumas. La mortalidad anual por causas especificas debida a la depredación confirmada (# 0.018), por los jaguares y la asumida (# 0.018), y así como toda la confirmada y asumida de los felinos (# 0.018), fue baja y la sobrevivencia de los becerros fue alta (0.89-0.98 anualmente). Si los becerros se reportaban como perdidos pero no se encontró evidencia de la mortalidad se clasificaron como depredación anual de de los felinos, así, la tasa de la ca...

The accuracy of microhiitological techniques for analysis of herbivore diets was evaluated with cattle, sheep, and Angora goats fed grass, forb, and shrub mixtures of known botanical compositions. Two observers performed microhistological analyses on undigested diets as offered and on feces collected. Similarity indices and chi-square tests were used to determine if differences existed among actual diets, estimated diets, and fecal samples. Botanical compositions of diets fed to all 3 anhnal species generally were accurately estimated by fecal analyses. In some other studies, shrubs in ruminant diets have been inaccurately estimated by the microhistological technique. However, in our study, shrubs were accurately estimated with no differences between actual and observed compositions. We attribute this to the fact that shrub materials used in our study had a high proportion of current growth relative to woody materials. Woody plant parts had lower proportions of identifiable epldermal material than leaves and young stems. In grass-forb diets, forbs sometimes were overestimated and differentiation among grasses was difficult. However, In most cases, observers could precisely estimate diets of the 3 herbivore species.

Mexico's wildlife has been impacted by human land use changes and socioeconomic and political factors since before the Spanish conquest in 1521. Presently, it has been estimated that more than 60% of the land area has been severely degraded. Mexico ranks in the top 3 countries in biodiversity, is a plant and faunal dispersal corridor, and is a crucial element in the conservation and management of North American wildlife. Wildlife management prerogatives and regulatory powers reside in the federal government with states relegated a minimum role. The continuous shifting of federal agencies responsible for wildlife management with the concomitant lack of adequate federal funding has not permitted the establishment of a robust wildlife program. In addition, wildlife conservation has been further impacted by a failure to establish landowner incentives, power struggles over user rights, resistance to change, and lack of trust and experience in protecting and managing Mexico's wildlife. We believe future strategies for wildlife programs must take into account Mexico's highly diversified mosaic of ecosystems, cultures, socioeconomic levels, and land tenure and political systems. The private sector, along with communal properties, in cooperation with federal and municipal governments, nongovernmental organizations, corporations, and international agencies may have the greatest potential of sustainable management of Mexico's wildlife. The present federal wildlife management strategy is an initial positive effort because it promotes participatory wildlife conservation by key stakeholders. We identify the aspects of this strategy that we believe will be needed to establish a sustainable program to manage Mexico's wildlife.

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