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Thermophilization is the directional change in species community composition towards greater relative abundances of species associated with warmer environments. This process is well-documented in temperate and Neotropical plant communities, but it is uncertain whether this phenomenon occurs elsewhere in the tropics. Here we extend the search for thermophilization to equatorial Africa, where lower tree diversity compared to other tropical forest regions and different biogeographic history could affect community responses to climate change. Using re-census data from 17 forest plots in three mountain regions of Africa, we find a consistent pattern of thermophilization in tree communities. Mean rates of thermophilization were +0.0086 °C·y−1 in the Kigezi Highlands (Uganda), +0.0032 °C·y−1 in the Virunga Mountains (Rwanda-Uganda-Democratic Republic of the Congo) and +0.0023 °C·y−1 in the Udzungwa Mountains (Tanzania). Distinct from other forests, both recruitment and mortality were important drivers of thermophilzation in the African plots. The forests studied currently act as a carbon sink, but the consequences of further thermophilization are unclear. Thermophilization is a change in species community composition towards greater abundances of species associated with warmer environments. This study provides evidence of thermophilization in understudied Afromontane forests, but with drivers that are distinct from other forest types. [ABSTRACT FROM AUTHOR]

Many bacterial pathogens, including the human exclusive pathogen Salmonella Typhi, express capsular polysaccharides as a crucial virulence factor. Here, through S. Typhi whole genome sequence analyses and functional studies, we found a list of single point mutations that make S. Typhi hypervirulent. We discovered a single point mutation in the Vi biosynthesis enzymes that control Vi polymerization or acetylation is enough to result in different capsule variants of S. Typhi. All variant strains are pathogenic, but the hyper Vi capsule variants are particularly hypervirulent, as demonstrated by the high morbidity and mortality rates observed in infected mice. The hypo Vi capsule variants have primarily been identified in Africa, whereas the hyper Vi capsule variants are distributed worldwide. Collectively, these studies increase awareness about the existence of different capsule variants of S. Typhi, establish a solid foundation for numerous future studies on S. Typhi capsule variants, and offer valuable insights into strategies to combat capsulated bacteria. Here, Lee and Song describe missense mutations in the viaB locus in clinical isolates of Salmonella Typhi that result in hypo- and hyper-virulent phenotypes due to changes in the capsule. [ABSTRACT FROM AUTHOR]

Off-grid photovoltaic systems have been proposed as a panacea for economies with poor electricity access, offering a lower-cost "leapfrog" over grid infrastructure used in higher-income economies. Previous research examining pathways to electricity access may understate the role of off-grid photovoltaics as it has not considered reliability and carbon pricing impacts. We perform high-resolution geospatial analysis on universal household electricity access in Sub-Saharan Africa that includes these aspects via least-cost pathways at different electricity demand levels. Under our "Tier 3" demand reference scenario, 24% of our study's 470 million people obtaining electricity access by 2030 do so via off-grid photovoltaics. Including a unit cost for unmet demand of 0.50 US dollars ($)/kWh, to penalise poor system reliability increases this share to 41%. Applying a carbon price (around $80/tonne CO2-eq) increases it to 38%. Our results indicate considerable diversity in the level of policy intervention needed between countries and suggest several regions where lower levels of policy intervention may be effective. This study investigates the role of off-grid solar in achieving SDG7 in Africa, focusing on understanding the impact of carbon pricing and supply reliability. It uses high-resolution spatial analysis and demand modelling to explore policy interventions for universal electricity access. [ABSTRACT FROM AUTHOR]

The global population is aging at the same time as heat exposures are increasing due to climate change. Age structure, and its biological and socio-economic drivers, determine populations' vulnerability to high temperatures. Here we combine age-stratified demographic projections with downscaled temperature projections to mid-century and find that chronic exposure to heat doubles across all warming scenarios. Moreover, >23% of the global population aged 69+ will inhabit climates whose 95th percentile of daily maximum temperature exceeds the critical threshold of 37.5 °C, compared with 14% today, exposing an additional 177–246 million older adults to dangerous acute heat. Effects are most severe in Asia and Africa, which also have the lowest adaptive capacity. Our results facilitate regional heat risk assessments and inform public health decision-making. By 2050 > 23% of the global population aged 69 + will live in climates with acute heat exposure– the 95th percentile of the distribution of maximum daily temperatures–greater than the critical threshold of 37.5C, compared with 14% in 2020, an increase of 177–246 million older adults exposed to dangerous acute heat. [ABSTRACT FROM AUTHOR]

Vaccines and clean water shortages continue to give rise to cholera outbreaks in Africa. Coordinated efforts to increase vaccine distribution and improve physical infrastructure are needed while considering future outbreaks and water demands due to conflicts and climate events. [ABSTRACT FROM AUTHOR]

Africa produces around 60% of the rice the continent consumes, relying heavily on rice imports to fulfill the rest of the domestic demand. Over the past 10 years, the rice-agricultural area increased nearly 40%, while average yield remained stagnant. Here we used a process-based crop simulation modelling approach combined with local weather, soil, and management datasets to evaluate the potential to increase rice production on existing cropland area in Africa and assess cropland expansion and rice imports by year 2050 for different scenarios of yield intensification. We find that Africa can avoid further increases in rice imports, and even reduce them, through a combination of cropland expansion following the historical trend together with closure of the current exploitable yield gap by half or more. Without substantial increase in rice yields, meeting future rice demand will require larger rice imports and/or land conversion than now. Here the authors demonstrate that cropland expansion following the historical trend together with closing the current exploitable yield gap by half or more across Africa reduces the continent's reliance on land conversions and imports by 2050. [ABSTRACT FROM AUTHOR]