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During past glacial‐interglacial cycles, the boreal summer insolation is the most crucial external forcing for climate change. However, the question of whether summer insolation is a key forcing on temperatures in the boreal tropics remains under debate, hampering our understanding of climate change at low latitudes. To shed further light on this issue, we performed a series of equilibrium simulations with the NorESM‐L model over the past 425 ka. Our simulations show that in the boreal tropical monsoon region, the simulated annual temperature is anti‐phased towards the boreal summer insolation. This antiphase relation is also supported by some available geological data. Additional diagnostic analyses reveal that the tropical warmth throughout the year is more reliant on winter temperatures than on summer temperatures. This stands in contrast to the situation in middle to high latitudes, particularly in the Mediterranean region. Further correlation analysis and spectrum analysis suggest that the annual temperature in boreal tropics is highly linked to local winter insolation. Our results highlight complex hydrothermal configurations in the boreal tropics, suggesting a decoupling of temperature and precipitation. Specifically, variations in annual temperature and precipitation in the boreal tropics are driven by distinct patterns of seasonal insolation. We deduce that the unique hydrothermal configurations in North Africa may have influenced the dispersal of early humans out of Africa. Plain Language Summary: On the orbital timescale, whether the temperature in boreal tropics is driven by boreal summer insolation still remains unclear. In this study, we conduct a comprehensive analysis of simulated results spanning the 425 ka. Our findings indicate that the annual temperature in boreal tropics is anti‐phased to the local summer insolation. Specifically, when local summer insolation is high (low), overall cooling (warming) occurs in the North African and South Asian monsoon regions. Some available paleo‐temperature records from the tropics also provide partial support for our simulation results. The temperature pattern in the boreal tropics is linked to the strong internal feedback in the summer from the unique climate background of the tropics, which results in relatively slight summer cooling at high boreal summer insolation, while the annual temperature is largely dependent on winter temperatures driven by local winter insolation. Our simulations reveal highly complex hydrothermal configurations in the boreal tropics on the orbital timescale, suggesting a decoupling of temperature and precipitation, with the former influenced by winter insolation and the latter forced by summer insolation. Key Points: The temperature in boreal tropical monsoon regions is anti‐phased to the boreal summer insolationThe annual temperature in boreal tropics is more dependent on the winter than summer temperaturesThe key role of local winter insolation in regulating the boreal tropical temperature is closely linked to its unique climatic background [ABSTRACT FROM AUTHOR]

The impact of biomass burning aerosols (BBA) emitted in Central Africa on the tropical African climate is studied using the ocean-atmosphere global climate model CNRM-CM, including prognostic aerosols. The direct BBA forcing, cloud feedbacks (semi-direct effects), effects on surface solar radiation, atmospheric dynamics and precipitation are analysed for the 1990–2014 period. During the June-July-August (JJA) season, the CNRM-CM simulations reveal a BBA semi-direct effect exerted on low-level clouds with an increase in cloud fraction of ∼5–10 % over a large part of the tropical ocean. The positive feedback of BBA radiative effects on low-level clouds is found to be mainly due to the sea surface temperature response (decrease of ~-0.5 K) associated with solar heating at 700 hPa, which increases the lower tropospheric stability. Over land, results also indicates a positive effect of BBA on the low cloud fraction especially for the coastal regions of Gabon and Angola with a potentially enhanced impact in these coupled simulations that integrate the response (cooling) of the SST. In addition to the BBA radiative effect on sea surface temperature, the ocean-atmosphere coupled simulations highlight that the oceanic temperature response is noticeable (about -0.2 to -0.4 K) down to ~80 m depth in the JJA between the African coast and 10°W. In parallel to low-level clouds, reductions of ~5–10 % are obtained for mid-level clouds over central Africa, mainly due to BBA-induced surface cooling and lower tropospheric heating inhibiting convection. In terms of cloud optical properties, the BBA radiative effects induced an increase of the optical depth by about ~2–3 south of the equator over the ocean. The result of the BBA direct effect and feedback on tropical clouds modulates the surface solar radiation over the whole Tropical Africa. The strongest surface dimming is over central Africa (~-30 W m−2), leading to a large reduction of the continental surface temperature (by ~-1 to -2 K), but the solar radiation at the oceanic surface is also affected up to the Brazilian coast. With respect to the hydrological cycle, the CNRM-CM simulations show a negative feedback on precipitation over the West African coast with a decrease of ~-1 to -2 mm per day. This study highlights also a persistent impact of BBA radiative effects on low-level clouds (increase in cloud fraction, liquid water content and optical depth) during the September-October-November (SON) period, mainly explained by a residual cooling of sea surface temperature over most of the tropical ocean. In SON, the feedback on precipitation is mainly simulated over the Gulf of Guinea with a reduction by ~-1 mm per day. As for JJA, the analysis clearly highlights the important role of the slow response of the ocean in SON and confirms the need to use coupled modelling platforms to study the impact of BBA on tropical African climate. [ABSTRACT FROM AUTHOR]

Climate parameters can be refined for use in a heritage context to capture climate‐based deterioration processes occurring on buildings and sites. The Scheffer index, which combines temperature and rainfall components, is commonly used as a metric of wood decay risk. Understanding how the index is likely to change is important for developing effective conservation strategies for timber heritage. However, there has been limited research assessing the agreement between climate model outputs for such heritage‐based metrics. This is especially important where capturing projected rainfall is known to be problematic, such as over regions of Africa. We address the following questions: to what extent is there model agreement over continental Africa for (i) the magnitude of the Scheffer index and (ii) the direction of change of future Scheffer indices. A multi‐model ensemble (MME) approach was used utilizing 13 CMIP6 models under the SPS585 scenario. Results showed that rainfall was important in determining the magnitude of the index. In regions where rainfall systems are not well captured by climate models, such as in eastern Africa, there was a large range in projected Scheffer values. To help with the transferability of the index to regions with a tropical climate, we suggest the addition of a Scheffer threshold for a very‐high risk of deterioration. Projections of future change to the index were found to be predominantly driven by changes in temperature, rather than rainfall. While there was considerable disagreement in the simulated magnitude of the Scheffer index, there was good agreement between models over the direction of change across Equatorial Africa, where the Scheffer index is greatest. Such agreement between models suggests that heritage decision makers can utilize the direction of change projected by models when shaping future conservation plans. [ABSTRACT FROM AUTHOR]

This review examines the published literature on the distribution and species richness of the family Mugilidae around six continents as well as their phylogenetic relationships in a time‐calibrated tree. Three mugilid species‐rich regions were identified globally, namely the Coral Triangle, southern Asia and southern Africa, all of which have between 16 and 18 morphologically recognized species. Two of the species hotspots are tropical, and only southern Africa incorporates temperate waters. The centre of mugilid evolution and then global dispersion appears to be located in the tropical waters of the Indo‐Pacific. Speciation within the family was promoted mainly by plate tectonics, eustatic sea‐level changes, tropical climate and high habitat diversity within this region. The number of these tropical species that radiated out to the coastal waters of Africa and America was clearly less than the number that remained in the central Indo‐Pacific region. Nonetheless, access by tropical mugilid species was greater to Africa than the Americas because of the direct tropical and subtropical coastal connectivity to the former continent. This enabled more tropical mugilids to reach Africa than America, with the latter probably relying on Palaeocene "island hopping" or "rafting" to move eastwards across the Pacific Ocean. In addition, tropical mugilids were able to access warm western and central African coastal waters from the Pacific prior to the closure of the Tethys Sea gap in the eastern Mediterranean and prior to the development of the cool Benguela Current upwelling off the southwest African coast, and from America through at least two transatlantic rafting events. [ABSTRACT FROM AUTHOR]

Solanum incanum L. is a plant that belongs to the Solanaceae family, growing in tropical climates all over the world. Despite the extensive use of the root and fruit sap extract of S. incanum in the agricultural and ethnopharmaceutical industries in Africa, there is minimal scientific documentation regarding its pesticide bioactive phytochemicals and efficacy. The study investigated the photochemical content (phenolics, flavonoids, saponins, terpenoids and alkaloids) of the methanol, ethyl acetate and hexane crude extracts of the root and fruit of S. incanum. The potential radical scavenging, (antioxidant), cytotoxicity, and efficacy activities of all crude extracts were examined using the 1, 1-diphenyl-2picrylhydrazyl (DPPH), propidium iodide (PI) and aphid leaf dip (ALD) assays respectively. The total phenolic, alkaloid, flavonoid, terpenoid and saponin content were highest in the methanol fruit (MFE), (3.49 ± 1.16 mg GAE/100 mg), steroidal fruit (SAE), (0.14±0.06 mg ATP/100 mg, hexane fruit (HFE), 3.62±1.23 mg QCT/100 mg, hexane root (Hroot), (1.19±0.47 mg LIN/100 mg and saponin (3.74±1.17 mg/100 mg). The aqueous extract of the ethyl acetate fruit had the highest antioxidant activity with an IC50 of 35.53±0.53 μg·mL-1 (p < 0.05) The methanol fruit and steroidal alkaloid extracts exhibited potent cytotoxicity against Vero cells demonstrating the highest cell mortality rate of 98% and 70% respectively at 100 μg·mL-1. Melphalan which was used as a positive control had a mortality rate of 75% cell at 100 μg/mL concentration. The methanol fruit extract exhibited the highest efficacy against the cabbage aphids with an LD50 of 13.16±3.78 μg·mL-1 (p < 0.05). The results indicated that the fruit and root of S. incanum have a variety of phytochemicals that may be considered for use as antioxidants and/or pesticides. By exhibiting the most potent cytotoxic activity against Vero cells, S. incanum roots have the greatest potential for the discovery of cytotoxic compounds necessary to develop anticancer drugs. The extracts with high potent efficacy against cabbage aphids need to be investigated further as pesticides to benefit the disadvantaged communities in the Southern African region. [ABSTRACT FROM AUTHOR]

The "One Health" concept considers that human and animal health, and ecosystems are closely related and aims to make a link between ecology and human and veterinary medicine. Due to the explosion in population growth along with the geographic and climatic conditions (equatorial and/or tropical climate), Africa is becoming a major hotspot for various socio-health issues associated with infectious diseases, including arboviruses. The incontestable advantages of a One Health approach in Africa lie in the fight against pathogens, such as arboviruses, and in the preservation of environmental, animal, and human health to ensure that the increasing high needs of this population are met as well as their protection against potential epidemics. The One Health strategy gives us a glimpse of the difficulties and challenges that the African continent faces. The importance of this approach in Africa is to establish guidelines and strategies for effective solutions and changes in behavior and harmful activities. Overall, the establishment of high-quality global health policies in the framework of the global health standards program would provide healthy and sustainable human–animal–environmental interactions for the welfare of all. [ABSTRACT FROM AUTHOR]

Chikungunya virus (CHIKV) is the responsible agent of chikungunya fever, a debilitating arthritic disease in humans. CHIKV is endemic in Africa and Asia, although transmission cycles are considerably different on these continents. Before 2004, CHIKV had received little attention, since it was only known to cause localised outbreaks in a limited region with no fatalities. However, the recent global reemergence of CHIKV has caused serious global health problems and shown its potential to become a significant viral threat in the future. Unexpectedly, the reemergence is more rapid and is geographically more extensive, especially due to increased intensity of global travel systems or failure to contain mosquito populations. Another important factor is the successful adaptation of CHIKV to a new vector, the Aedes albopictus mosquito. Ae. albopictus survives in both temperate and tropical climates, thus facilitating CHIKV expansion to non-endemic regions. The continuous spread and transmission of CHIKV pose challenges for the development of effective vaccines and specific antiviral therapies. In this review, we discuss the biology and origin of CHIKV in Africa as well as its subsequent expansion to other parts of the world. We also review the transmission cycle of CHIKV and its continuing adaptation to its mosquito vectors and vertebrate hosts. More-complete understanding of the continuous evolution of CHIKV may help in predicting the emergence of CHIKV strains with possibly greater transmission efficiency in the future. [ABSTRACT FROM AUTHOR]

At the end of the nineteenth century, British imperial doctors found that the glycerinated lymph they received from British-based pharmaceutical companies became inert, failing to protect colonial populations against smallpox. Colonial doctors and their British suppliers thus took a fresh look at the preservation media used for lymph as they discovered how different kinds of lymph reacted to 'tropical' climates. British lymph distributors like the Society of Apothecaries sought to maintain their economic hold and influence on the colonies, which provided them with significant commercial outlets to sell lymph, through exploring new modes of preserving lymph. Colonial doctors, however, used the issue to argue for the ability to locally produce vaccine, creating a more economical and dependable production line for the colonies. Building on scholarship on imperial climates, public health, and pharmaceutical manufacturing, I argue that together, colonial climates and local preferences forced calf vaccine lymph producers and users in Britain to redefine their ideas about what constituted smallpox vaccination. These issues affected where colonial lymph was produced and who benefited from lymph's economic power and scientific authority across international borders, exposing how the tropical colonial climate shifted how long-standing medical technologies were produced and distributed across international borders. [ABSTRACT FROM AUTHOR]

By that time the patient had fever (38.2°C) and described a local creeping sensation as well as localized lancinating pain around inflammatory nodules. Dear Editor, A 41-year-old Caucasian male patient was hospitalized showing multiple furunkuloid inflamed nodules on his trunk and arms. When it comes to Myiasis, the patients often show single nodules which in an early stage of infestation can easily be misdiagnosed as an inflamed atheroma or as a folliculitis. [Extracted from the article]

Rising interest in large-scale afforestation and reforestation as a strategy for climate change mitigation has recently motivated research efforts aiming at the identification of areas suitable for the plantation of trees. An often-overlooked aspect of agroforestry projects for carbon sequestration is their impact on water resources. It is often unclear to what extent the establishment of forest vegetation would be limited by water availability, whether it would engender competition with other local water uses or induce water scarcity. Here we use global water models to study the hydrologic constraints and impacts of afforestation in tropical biomes. We find that 36% of total suitable and available afforestation areas are in areas where the rain alone can meet just up to the 40% of total plant water requirement. Planting trees will substantially increase water scarcity and possible dispossession (green water grab) especially in dryland regions of Africa and Oceania. Moreover, the combination of tree restoration and irrigation expansion to rainfed agricultural areas is expected to further exacerbate water scarcity, with about half of the global suitable areas for tree restoration experiencing water scarcity at least 7 months per year. Thus, the unavailability of water can overall limit climate change adaptation strategies. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'. [ABSTRACT FROM AUTHOR]

Tropical montane forest ecosystems are pivotal for sustaining biodiversity and essential terrestrial ecosystem services, including the provision of high-quality fresh water. Nonetheless, the impact of montane deforestation and climate change on the capacity of forests to deliver ecosystem services is yet to be fully understood. In this study, we offer observational evidence demonstrating the response of air temperature and cloud base height to deforestation in African montane forests over the last two decades. Our findings reveal that approximately 18% (7.4 ± 0.5 million hectares) of Africa's montane forests were lost between 2003 and 2022. This deforestation has led to a notable increase in maximum air temperature (1.37 ± 0.58 °C) and cloud base height (236 ± 87 metres), surpassing shifts attributed solely to climate change. Our results call for urgent attention to montane deforestation, as it poses serious threats to biodiversity, water supply, and ecosystem services in the tropics., (© 2024. The Author(s).)

Rapid and uncontrolled urbanization in tropical Africa is increasingly leading to unprecedented socio-economical and environmental challenges in cities, particularly urban heat and climate change. The latter calls for a better representation of tropical African cities' properties relevant for urban climate studies. Here, we demonstrate the possibility of collecting urban canopy parameters during a field campaign in the boreal summer months of 2018 for deriving a Local Climate Zone (LCZ) map and for improving the physical representation of climate-relevant urban morphological, thermal and radiative characteristics. The comparison of the resulting field-derived LCZ map with an existing map obtained from the World Urban Data and Access Portal Tool framework shows large differences. In particular, our map results in more vegetated open low-rise classes. In addition, site-specific fieldwork-derived urban characteristics are compared against the LCZ universal parameters. The latter shows that our fieldwork adds important information to the universal parameters by more specifically considering the presence of corrugated metal in the city of Kampala. This material is a typical roofing material found in densely built environments and informal settlements. It leads to lower thermal emissivity but higher thermal conductivity and capacity of buildings. To illustrate the importance of site-specific urban parameters, the newly derived site-specific urban characteristics are used as input fields to an urban parametrization scheme embedded in the regional climate model COSMO-CLM. This implementations decreases the surface temperature bias from 5.34 to 3.97 K. Based on our results, we recommend future research on tropical African cities to focus on a detailed representation of cities, with particular attention to impervious surface fraction and building materials. [ABSTRACT FROM AUTHOR]

Background: Febrile illnesses that persist despite initial treatment are common clinical challenges in (sub)tropical low-resource settings. Our aim is to review infectious etiologies of "prolonged fevers" (persistent febrile illnesses, PFI) and to quantify relative contributions of selected neglected target diseases with limited diagnostic options, often overlooked, causing inadequate antibiotic prescriptions, or requiring prolonged and potentially toxic treatments., Methods: We performed a systematic review of articles addressing the infectious etiologies of PFI in adults and children in sub-/tropical low- and middle-income countries (LMICs) using the PRISMA guidelines. A list of target diseases, including neglected parasites and zoonotic bacteria (e.g., Leishmania and Brucella), were identified by infectious diseases and tropical medicine specialists and prioritized in the search. Malaria and tuberculosis (TB) were not included as target diseases due to well-established epidemiology and diagnostic options. Four co-investigators independently extracted data from the identified articles while assessing for risk of bias., Results: 196 articles from 52 countries were included, 117 from Africa (33 countries), 71 from Asia (16 countries), and 8 from Central and -South America (3 countries). Target diseases were reported as the cause of PFI in almost half of the articles, most frequently rickettsioses (including scrub typhus), relapsing fever borreliosis (RF-borreliosis), brucellosis, enteric fever, leptospirosis, Q fever and leishmaniasis. Among those, RF-borreliosis was by far the most frequently reported disease in Africa, particularly in Eastern Africa. Rickettsioses (including scrub typhus) were often described in both Africa and Asia. Leishmaniasis, toxoplasmosis and amoebiasis were the most frequent parasitic etiologies. Non-target diseases and non-tropical organisms (Streptococcus pneumoniae, Escherichia coli, and non-typhoidal Salmonella spp) were documented in a fifth of articles., Conclusions: Clinicians faced with PFI in sub-/tropical LMICs should consider a wide differential diagnosis including enteric fever and zoonotic bacterial diseases (e.g., rickettsiosis, RF-borreliosis and brucellosis), or parasite infections (e.g., leishmaniasis) depending on geography and syndromes. In the absence of adequate diagnostic capacity, a trial of antibiotics targeting relevant intra-cellular bacteria, such as doxycycline or azithromycin, may be considered., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Musumeci et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

This review examines high-quality research evidence that synthesises the effects of extreme heat on human health in tropical Africa. Web of Science (WoS) was used to identify research articles on the effects extreme heat, humidity, Wet-bulb Globe Temperature (WBGT), apparent temperature, wind, Heat Index, Humidex, Universal Thermal Climate Index (UTCI), heatwave, high temperature and hot climate on human health, human comfort, heat stress, heat rashes, and heat-related morbidity and mortality. A total of 5, 735 articles were initially identified, which were reduced to 100 based on a set of inclusion and exclusion criteria. The review discovered that temperatures up to 60°C have been recorded in the region and that extreme heat has many adverse effects on human health, such as worsening mental health in low-income adults, increasing the likelihood of miscarriage, and adverse effects on well-being and safety, psychological behaviour, efficiency, and social comfort of outdoor workers who spend long hours performing manual labour. Extreme heat raises the risk of death from heat-related disease, necessitating preventative measures such as adaptation methods to mitigate the adverse effects on vulnerable populations during hot weather. This study highlights the social inequalities in heat exposure and adverse health outcomes., (© 2024. The Author(s).)

Background and Aim: Plant disjunctions have fascinated biogeographers and ecologists for a long time. We use tribe Bocageeae (Annonaceae), a predominantly Neotropical plant group distributed across several present-day Neotropical biomes and with an African-American disjunction, to investigate long-distance dispersal mediated by frugivorous animals at both intercontinental and intracontinental scales., Methods: We reconstructed a species-level phylogeny of tribe Bocageeae with a dataset composed of 116 nuclear markers. We sampled 70 % of Bocageeae species, covering their geographical range and representing all eight genera. We estimated divergence times using BEAST, inferred ancestral range distributions and reconstructed ancestral states for fruit traits related to long-distance dispersal in a Bayesian framework., Key Results: The ancestral Bocageeae date to the Early Eocene and were inferred to occur in Africa and proto-Amazonia. Their ancestral fruits were large and dehiscent. The first lineage split gave rise to an exclusively Neotropical clade during the Middle Eocene, in proto-Amazonia. Range exchange between the Amazon and the Atlantic Forest occurred at least once during the Miocene, and from Amazonia to Central America and Mexico during the Early Miocene. Transitions in different sets of fruit morphologies were inferred to be related to dispersal events across South American regions/biomes., Conclusions: In Bocageeae, mammals might have been responsible for long-distance dispersal through the Boreotropics. In the Neotropics, proto-Amazonia is proposed to be the source for dispersal to other tropical American biomes. Long-distance dispersal might have happened via a wide range of dispersal guilds, depending on frugivore radiations, diversity and abundance in particular time periods and places. Hence, inter- and intracontinental dispersal might not rely on a single dispersal syndrome or guild, but more on the availability of frugivorous lineages for seed dispersal., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Deforestation, landscape dynamics, and socioeconomic factors within the tropical Americas, Africa, and Asia may have different impacts on malaria incidence. To evaluate how these drivers affect malaria incidence at the global and regional scale, we collected malaria incidence rates from 2000 to 2019 from 67 tropical countries, along with forest loss, land use change types, and socioeconomic elements. LASSO regression, linear mixed effect modeling, and k-fold cross validation were used to create and evaluate the models. Regionality plays a role in the significance of varying risk factors. The Tropical Americas model had the highest coefficient of determination (marginal R 2 = 0.369), while the Africa model showed the highest predictive accuracy with only a 17.4% error rate. Strong associations between tree cover loss (β = -4037.73, p < 0.001) and percentage forest area (β = 5373.18, p = 0.012) in Africa, and percent of key biodiversity areas under protection (β = 496.71, p < 0.001; β = 1679.20, p < 0.001) in the tropical Americas and Asia with malaria incidence indicates that malaria risk should be considered during conservation policy development, and recommends that individual approaches to policy and investment be considered when implementing malaria interventions on different spatial scales.

This article describes a software suite that can be used for objective evaluation of tropical cyclones (TCs) in gridded climate data. Using cyclone trajectories derived from 6-hourly data, a comprehensive set of metrics is defined to systematically compare and contrast products with one another. In addition to annual TC climatologies, attention is paid to spatial and temporal patterns of storm occurrence and intensity. Assessment can be performed either on the global scale or for regional domains. Simple-to-visualize "scorecards" allow for rapid credibility assessment. We showcase three key findings enabled by this suite. First, we compare the representation of TCs in seven current-generation global reanalyses and conclude that higher-resolution models and those with TC-specific assimilation contain more accurate storm climatologies. Second, using a free-running Earth system model (ESM) we find that full basin refinement is required in variable-resolution configurations to adequately simulate North Atlantic Ocean TC frequency. Upstream refinement over northern Africa offers little benefit in simulating storm occurrence, but spatial genesis patterns are improved. We also show that TCs simulated by ESMs can be highly sensitive to individual parameterizations in climate models, with North Atlantic TC metrics varying greatly depending on the version of the Morrison-Gettelman microphysics package that is used. [ABSTRACT FROM AUTHOR]

[Display omitted] • The total water yield capacity in Africa is projected to decline in the future compared to the current situation. • WYC will reduce most in the areas experiencing the conversion between tropical monsoon and tropical rainforest climates. • The areas producing water yield capacity will be more concentrated in the future. • Water yield was driven by precipitation, temperature, NPP and landscape pattern, which had spatial scale effect. Predicting the water-related services of terrestrial ecosystems in a changing climate is of great significance for managing rich ecosystems in water-scarce areas. Water yield capacity (WYC), which characterizes water resource availability, was thrown into sharp focus of this study. The spatiotemporal trends of WYC and their dynamics by potential climate shifts were evaluated based on calculative WYC and climate zones for historical period (2001–2018) and future scenarios (both 2050 and 2100 under SSP1-2.6 or SSP5-8.5 scenarios). The multiple factors affecting WYC in the recent past were identified as the basis for explaining the future tendency in WYC. All analyses were conducted from the perspective of holistic continental scale and specific basin scale so as to explore the contrast between various scales. The results showed that the total WYC both in whole Africa and the four major basins (the Congo, the Nile, the Niger and the Zambezi) are projected to decrease in 2050 and 2100 compared with that in 2018, under both SSP1-2.6 or SSP5-8.5 scenarios describing future pathways with low or high greenhouse gas emissions, respectively. The areas producing WYC will be more concentrated, suggesting that the proportion of areas contributing to the top 50% of this function across Africa will drop from current 10.5% to 4.94% in 2100 under SSP5-8.5 scenario. As climate zones are likely to shift in the future, the WYC will reduce most in the areas experiencing the conversion between tropical monsoon and tropical rainforest climates. In addition, WYC was driven by precipitation, temperature, net primary productivity (NPP) and landscape pattern (connectivity and diversity), which had spatial scale effect. The results add evidence for unstable availability of water resources provided by terrestrial ecosystems in a multi-scale manner. [ABSTRACT FROM AUTHOR]

Carbon finance projects that protect tropical forests could support both nature conservation and climate change mitigation goals. Global demand for nature-based carbon credits is outpacing their supply, due partly to gaps in knowledge needed to inform and prioritize investment decisions. Here, we show that at current carbon market prices the protection of tropical forests can generate investible carbon amounting to 1.8 (±1.1) GtCO2e yr−1 globally. We further show that financially viable carbon projects could generate return-on-investment amounting to $46.0b y−1 in net present value (Asia-Pacific: $24.6b y−1; Americas: $19.1b y−1; Africa: $2.4b y−1). However, we also find that ~80% (1.24 billion ha) of forest carbon sites would be financially unviable for failing to break even over the project lifetime. From a conservation perspective, unless carbon prices increase in the future, it is imperative to implement other conservation interventions, in addition to carbon finance, to safeguard carbon stocks and biodiversity in vulnerable forests. Investing in forest protection is a way to generate tradable carbon credits to support biodiversity conservation and climate change mitigation. Here the authors assess and map the global supply of tropical forest carbon credits with the goal of informing climate policy and investments. [ABSTRACT FROM AUTHOR]

Tropical Africa is home to an astonishing biodiversity occurring in a variety of ecosystems. Past climatic change and geological events have impacted the evolution and diversification of this biodiversity. During the last two decades, around 90 dated molecular phylogenies of different clades across animals and plants have been published leading to an increased understanding of the diversification and speciation processes generating tropical African biodiversity. In parallel, extended geological and palaeoclimatic records together with detailed numerical simulations have refined our understanding of past geological and climatic changes in Africa. To date, these important advances have not been reviewed within a common framework. Here, we critically review and synthesize African climate, tectonics and terrestrial biodiversity evolution throughout the Cenozoic to the mid‐Pleistocene, drawing on recent advances in Earth and life sciences. We first review six major geo‐climatic periods defining tropical African biodiversity diversification by synthesizing 89 dated molecular phylogeny studies. Two major geo‐climatic factors impacting the diversification of the sub‐Saharan biota are highlighted. First, Africa underwent numerous climatic fluctuations at ancient and more recent timescales, with tectonic, greenhouse gas, and orbital forcing stimulating diversification. Second, increased aridification since the Late Eocene led to important extinction events, but also provided unique diversification opportunities shaping the current tropical African biodiversity landscape. We then review diversification studies of tropical terrestrial animal and plant clades and discuss three major models of speciation: (i) geographic speciation via vicariance (allopatry); (ii) ecological speciation impacted by climate and geological changes, and (iii) genomic speciation via genome duplication. Geographic speciation has been the most widely documented to date and is a common speciation model across tropical Africa. We conclude with four important challenges faced by tropical African biodiversity research: (i) to increase knowledge by gathering basic and fundamental biodiversity information; (ii) to improve modelling of African geophysical evolution throughout the Cenozoic via better constraints and downscaling approaches; (iii) to increase the precision of phylogenetic reconstruction and molecular dating of tropical African clades by using next generation sequencing approaches together with better fossil calibrations; (iv) finally, as done here, to integrate data better from Earth and life sciences by focusing on the interdisciplinary study of the evolution of tropical African biodiversity in a wider geodiversity context. [ABSTRACT FROM AUTHOR]

An analysis of over 1 million old-growth tropical forest trees reveals that ∼2.2% of species comprise 50% of the individuals in Africa, Amazonia, and Southeast Asia, suggesting that the ecological mechanisms underpinning tree community assembly are ubiquitous across the tropics., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations 1-6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories 7 , we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees., (© 2024. The Author(s).)

Household digesters are anaerobic reactors applied mostly in rural areas of developing countries with tropical climate. The Chinese dome digester is the most popular household digester type in Asia and Africa, and has become the basis for contemporary developments in the household digester sector around the world. Household digesters are operated at ambient temperatures and have no internal mixing device, making them simple to operate. In the absence of internal mixing mechanism, the Chinese dome digester is mixed via pressure variation during gas production, gas use and feeding. Since mixing is limited in household digesters, they are operated at low organic loading rates and long hydraulic retention time when compared with forced mixed reactors. This review analyses and presents the various types of domestic biogas plants and operating parameters, with emphasis on mixing. Experimental results of household reactors, forced mixed reactors with different mixing modes and intensities were also reviewed and compared. [ABSTRACT FROM AUTHOR]

Palm diversity in present-day Africa is much less than in other tropical regions such as the Americas and Southeast Asia but comprises several endemic genera, including Sclerosperma. The origin and evolution of this small Arecaceae genus are still enigmatic, and every new fossil discovered helps fill the void in its palaeophytogeographic history. In this article, we report five different pollen morphologies assigned to Sclerosperma from the earliest Late Eocene (early Priabonian) of southeast Kenya, Africa. These pollen grains represent the earliest fossil records of Sclerosperma so far and add a new geographic region and time slot to the palaeophytogeographic history of this genus. The morphological variability observed in the fossil pollen suggests that the diversification within Sclerosperma was already underway by the onset of the Priabonian, c. 37 Ma. Detailed analysis of the distribution of the three extant Sclerosperma species shows that this genus occurs only under Equatorial/Tropical climates with MTCM ≥ 18 °C, such as fully humid Rainforest (Af), Monsoonal (Am), and winter dry Savannah (Aw) climates. Sclerosperma is also conservative when it comes to vegetation biomes and only occurs in three different but closely related biomes, the Tropical & Subtropical Moist Forests Biome, the Tropical & Subtropical Grasslands, Savannahs & Shrublands Biome, and the Mangroves Biome. No current outliners pinpoint to a wider ecological tolerance of this genus in the geological past. This suggests Sclerosperma to be an exceptionally reliable taxon for palaeoclimate estimations and when assigning palaeofloras to major vegetation biomes. • Eocene Sclerosperma pollen grains are the oldest fossils from this enigmatic palm. • Pollen morphotypes suggest intrageneric divergence prior to the Late Eocene. • Fossil records of Sclerosperma suggests they were always endemic to tropical Africa. • Sclerosperma fossils can be used to estimate paleoclimate and past vegetation biomes. [ABSTRACT FROM AUTHOR]

Although originating from a common Gondwanan flora, the diversity and composition of the floras of Africa and South America have greatly diverged since continental breakup of Africa from South America now having much higher plant species richness. However, the phylogenetic diversity of the floras and what this tells us about their evolution remained unexplored. We show that for a given species richness and considering land surface area, topography, and present-day climate, angiosperm phylogenetic diversity in South America is higher than in Africa. This relationship holds regardless of whether all climatically matched areas or only matched areas in tropical climates are considered. Phylogenetic diversity is high relative to species richness in refugial areas in Africa and in northwestern South America, once the gateway for immigration from the north. While species richness is strongly influenced by massive plant radiations in South America, we detect a pervasive influence of historical processes on the phylogenetic diversity of both the South American and African floras.

The role of climate change on mycotoxin profile and activity was reviewed. The unprecedented spread and relocation experienced by some regulated mycotoxins on food and feed items were investigated. Aspergillus species and aflatoxin, originally associated with tropical and subtropical climate characteristics of Sub-Saharan Africa are now comfortable guests in temperate zones. The same applies to Fusarium and Penicilium species, earlier thought to be strictly specific to temperate regions of Europe, now encountered in tropical Africa, with their toxins like zearalenone and trichothecenes, particularly in recent surveillance studies. This review is an update on the unstable trend on a global mycotoxin map with reference to the obvious climatic dynamics, having Africa in view. [ABSTRACT FROM AUTHOR]

Aim: The climate tolerances of many species are broader than those estimated from current native ranges. Indeed, the niches of some Afromontane trees are up to 50% larger after incorporation of fossil data. This expansion could reduce estimates of species' future range loss owing to climate change but also implies strong non‐climatic limitations on species' current ranges. One such limitation is land use, which fossil data suggest influences Afromontane tree distribution, preventing these trees from occupying warmer conditions than they do currently. We aimed to assess the degree to which the broader climatic tolerances revealed by fossil data buffer projected range loss from climate and land use for Afromontane trees. Location: Africa. Time period: Last 21,000 years. Major taxa studied: Afromontane trees. Methods: We used species distribution models informed by both current and fossil distributions to project future ranges under climate and land‐use projections. Results: We found that projected range reductions are only slightly ameliorated by incorporation of fossil distributions, and these improvements diminish further under severe land‐use or climate change scenarios. Taxa that are less impacted by climate are more impacted by intense land use. Depending on the severity of climate and land use, the geographical extent of Afromontane tree species' ranges will contract by 40–85%, and the trees will be completely lost from large portions of Africa. We projected that the surviving species' ranges will become increasingly fragmented. Main conclusions: Maintaining Afromontane ecosystems will require mitigation of both climate and land‐use change and protection of areas to optimize connectivity. Our findings caution that species with climate tolerances broader than their current range might not necessarily fare better under strong changes in climate or land use. [ABSTRACT FROM AUTHOR]

Aim: Rapid global environmental change predicts increasingly seasonal climate in the tropics, causing expansion of seasonally dry habitats and leading to shifts in species distribution and potential extinction. Here, we use a macroevolutionary framework to understand the processes driving palm diversity patterns between moist and seasonally dry tropical habitats. We hypothesize that the discrepancy in species richness between habitats is explained by higher speciation rates in moist habitat and that niche conservatism prevents frequent shifts between habitats. Location: Global. Time period: Last 100 Ma. Major taxa studied: Arecaceae. Methods: We used trait‐dependent diversification models to test whether different habitats affect palm speciation rates. Furthermore, palm assemblages were divided into three regions (Africa, Australasia and Neotropics) to test for niche conservatism and evaluate phylogenetic dissimilarity. Results: We found no relationship between speciation rate and habitat type. We detected phylogenetic signal for habitats at both global and continental scales, indicating that closely related species were more similar than expected by chance. Colonization of seasonally dry habitats occurred c. 60 Ma, yet most clades only diversified after c. 30 Ma. The high phylogenetic dissimilarity between habitat types at both global and continental scales was driven by high lineage turnover, at least for Africa and the Neotropics. Main conclusions: We found a lack of differential speciation rates in setting the seasonally dry and moist palm‐richness discrepancy. However, over evolutionary history most palm lineages fail to colonize seasonally dry habitats owing to a tendency to retain ancestral habitat. Indeed, seasonally dry palm assemblages are the result of the diversification of particular lineages. Likewise, long‐term dry periods appear to induce shifts in taxonomic and functional diversity, and we emphasize that the expansion of dry habitats might also imply a loss of palm clades, hence a reduction in phylogenetic diversity. [ABSTRACT FROM AUTHOR]

Moringa oleifera Lam commonly known as Moringa, a native plant from Africa and Asia, and the most widely cultivated species in Northwestern India, is the sole genus in the family Moringaceae. It comprises 13 species from tropical and subtropical climates, ranging in size from tiny herbs to massive trees. It is grown for its nutritious pods, edible leaves and flowers and can be utilized as food, medicine, cosme tic oil or forage for livestock. Its height ranges from 5 to 10 m. Several studies have demonstrated the beneficial effects in humans. MO has been recognized as containing a great number of bioactive compounds. The most used parts of the plant are the leaves, which are rich in vitamins, carotenoids, polyphenols, phenolic acids, flavonoids, alkaloids, glucosinolates, isothiocyanates, tannins and saponins. The present investigation was carried out to evaluate anti-ulcer activity of various extract of the plant. [ABSTRACT FROM AUTHOR]

Forecasting convective rainfall in the tropics is a major challenge for numerical weather prediction. The use of convection-permitting (CP) forecast models in the tropics has lagged behind the midlatitudes, despite the great potential of such models in this region. In the scientific literature, there is very little evaluation of CP models in the tropics, especially over an extended time period. This paper evaluates the prediction of convective storms for a period of 2 years in the Met Office operational CP model over East Africa and the global operational forecast model. A novel localized form of the fractions skill score is introduced, which shows variation in model skill across the spatial domain. Overall, the CP model and the global model both outperform a 24-h persistence forecast. The CP model shows greater skill than the global model, in particular on subdaily time scales and for storms over land. Forecasts over Lake Victoria are also improved in the CP model, with an increase in hit rate of up to 20%. Contrary to studies in the midlatitudes, the skill of both models shows a large dependence on the time of day and comparatively little dependence on the forecast lead time within a 48-h forecast. Although these results provide more motivation for forecasters to use the CP model to produce subdaily forecasts with increased detail, there is a clear need for more in situ observations for data assimilation into the models and for verification. A move toward ensemble forecasting could have further benefits. [ABSTRACT FROM AUTHOR]

This study advances the practicality and stability of the traditional multivariate statistical method, generalized equilibrium feedback assessment (GEFA), for decomposing the key oceanic drivers of regional atmospheric variability, especially when available data records are short. An advanced stepwise GEFA methodology is introduced, in which unimportant forcings within the forcing matrix are eliminated through stepwise selection. Method validation of stepwise GEFA is performed using the CESM, with a focused application to northern and tropical Africa (NTA). First, a statistical assessment of the atmospheric response to each primary oceanic forcing is carried out by applying stepwise GEFA to a fully coupled control run. Then, a dynamical assessment of the atmospheric response to individual oceanic forcings is performed through ensemble experiments by imposing sea surface temperature anomalies over focal ocean basins. Finally, to quantify the reliability of stepwise GEFA, the statistical assessment is evaluated against the dynamical assessment in terms of four metrics: the percentage of grid cells with consistent response sign, the spatial correlation of atmospheric response patterns, the area-averaged seasonal cycle of response magnitude, and consistency in associated mechanisms between assessments. In CESM, tropical modes, namely El Niño-Southern Oscillation and the tropical Indian Ocean Basin, tropical Indian Ocean dipole, and tropical Atlantic Niño modes, are the dominant oceanic controls of NTA climate. In complementary studies, stepwise GEFA is validated in terms of isolating terrestrial forcings on the atmosphere, and observed oceanic and terrestrial drivers of NTA climate are extracted to establish an observational benchmark for subsequent coupled model evaluation and development of process-based weights for regional climate projections. [ABSTRACT FROM AUTHOR]

Animal tolerance towards humans can be a key factor facilitating wildlife-human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene., (© 2023. The Author(s).)

This study investigates the Intertropical Convergence Zone (ITCZ) response to extratropical thermal forcing applied to an atmospheric general circulation model coupled to slab ocean and land models. We focus on the relative roles of the atmosphere, tropical sea surface temperatures (SSTs) and continental surface temperatures in the ITCZ response to the imposed forcing. The forcing consists of cooling in one hemisphere and warming in the other poleward of 40°, with zero global average. Three sets of experiments are performed: in the first the slab ocean and land models are applied globally; in the second the tropical SSTs are kept fixed while the slab land model is applied globally; in the third, in addition, surface temperatures over Africa are kept fixed. Realistic boundary surface conditions are used. We find that the ITCZ shifts towards the warmer hemisphere and that the stronger the forcing, the larger the shift. When the constraint of fixed tropical SST is imposed we find that the ITCZ response is strongly weakened, but it is still not negligible in particular over the Atlantic Ocean and Africa where the precipitation anomalies are of the order of 20 and 60 %, respectively, of the magnitude obtained without the SST restriction. Finally, when the constraint of the African surface temperature is incorporated we find that the ITCZ response completely vanishes, indicating that the ITCZ response to the extratropical forcing is not possible just trough purely atmospheric processes, but needs the involvement of either the tropical SST or the continental surface temperatures. The clear-sky longwave radiation feedback is highlighted as the main physical mechanism operating behind the land-based extratropical to tropical communication. [ABSTRACT FROM AUTHOR]

Background: Tropical and subtropical Africa is predicted to experience a rise in temperature. The effects of rising temperatures on temperate grasslands have been studied using open-top chambers (OTCs) but reports for tropical/subtropical grasslands are scarce. This study used OTCs to investigate the effects of elevated temperatures on a threatened subtropical grassland type, namely KwaZulu-Natal Sandstone Sourveld (KZNSS). Objectives: To assess the effects of OTCs on selected abiotic parameters and plant productivity within KZNSS. Methods: Five OTC and control plots were randomly distributed at the same altitude within a patch of KZNSS. Air and soil temperature, relative humidity (RH), soil moisture content and light intensity were monitored in all plots in spring, summer, autumn and winter. Biomass production and plant density were measured in each season, for each life form (graminoid, forb and shrub), separately and combined. Results: The OTCs resulted in a rise in average, maximum and minimum day and night, air and soil temperatures. This increase, the degree of which differed across seasons, was accompanied by a decline in RH and soil moisture content. Elevated temperatures led to a significant increase in combined, graminoid and shrub above-ground productivity (AGP) and a decrease in forb density, but in certain seasons only. Below-ground biomass production was unaffected by elevated temperatures. Conclusions: OTCs can simulate realistic increases of air temperature in subtropical grasslands. Graminoids and shrubs appear to benefit from elevated temperatures whilst forbs decrease in abundance, possibly through competition and/or direct physiological effects. [ABSTRACT FROM AUTHOR]

The evolution of El Niño can be separated into two phases-namely, growth and mature-depending on whether the regional sea surface temperature has adjusted to the tropospheric warming in the remote tropics (tropical regions away from the central and eastern tropical Pacific Ocean). The western Sahel's main rainy season (July-September) is shown to be affected by the growth phase of El Niño through (i) a lack of neighboring North Atlantic sea surface warming, (ii) an absence of an atmospheric column water vapor anomaly over the North Atlantic and western Sahel, and (iii) higher atmospheric vertical stability over the western Sahel, resulting in the suppression of mean seasonal rainfall as well as number of wet days. In contrast, the short rainy season (October-December) of tropical eastern Africa is impacted by the mature phase of El Niño through (i) neighboring Indian Ocean sea surface warming, (ii) positive column water vapor anomalies over the Indian Ocean and tropical eastern Africa, and (iii) higher atmospheric vertical instability over tropical eastern Africa, leading to an increase in the mean seasonal rainfall as well as in the number of wet days. While the modulation of the frequency of wet days and seasonal mean accumulation is statistically significant, daily rainfall intensity (for days with rainfall > 1 mm day−1), whether mean, median, or extreme, does not show a significant response in either region. Hence, the variability in seasonal mean rainfall that can be attributed to the El Niño-Southern Oscillation phenomenon in both regions is likely due to changes in the frequency of rainfall. [ABSTRACT FROM AUTHOR]

Tropical climate is rapidly changing, but the effects of these changes on the geosphere are unknown, despite a likelihood of climatically-induced changes on weathering and erosion. The lack of long, continuous paleo-records prevents an examination of terrestrial responses to climate change with sufficient detail to answer questions about how systems behaved in the past and may alter in the future. We use high-resolution records of pollen, clay mineralogy, and particle size from a drill core from Lake Malawi, southeast Africa, to examine atmosphere-biosphere-geosphere interactions during the last deglaciation (∼18–9 ka), a period of dramatic temperature and hydrologic changes. The results demonstrate that climatic controls on Lake Malawi vegetation are critically important to weathering processes and erosion patterns during the deglaciation. At 18 ka, afromontane forests dominated but were progressively replaced by tropical seasonal forest, as summer rainfall increased. Despite indication of decreased rainfall, drought-intolerant forest persisted through the Younger Dryas (YD) resulting from a shorter dry season. Following the YD, an intensified summer monsoon and increased rainfall seasonality were coeval with forest decline and expansion of drought-tolerant miombo woodland. Clay minerals closely track the vegetation record, with high ratios of kaolinite to smectite (K/S) indicating heavy leaching when forest predominates, despite variable rainfall. In the early Holocene, when rainfall and temperature increased (effective moisture remained low), open woodlands expansion resulted in decreased K/S, suggesting a reduction in chemical weathering intensity. Terrigenous sediment mass accumulation rates also increased, suggesting critical linkages among open vegetation and erosion during intervals of enhanced summer rainfall. This study shows a strong, direct influence of vegetation composition on weathering intensity in the tropics. As climate change will likely impact this interplay between the biosphere and geosphere, tropical landscape change could lead to deleterious effects on soil and water quality in regions with little infrastructure for mitigation. [ABSTRACT FROM AUTHOR]

This study reveals rainfall variability and trends in the African continent using TAMSAT data from 1983 to 2020. In the study, a Mann–Kendall (MK) test and Sen's slope estimator were used to analyze rainfall trends and their magnitude, respectively, under monthly, seasonal, and annual timeframes as an indication of climate change using different natural and geographical contexts (i.e., sub-regions, climate zones, major river basins, and countries). The study finds that the highest annual rainfall trends were recorded in Rwanda (11.97 mm/year), the Gulf of Guinea (river basin 8.71 mm/year), the tropical rainforest climate zone (8.21 mm/year), and the Central African region (6.84 mm/year), while Mozambique (−0.437 mm/year), the subtropical northern desert (0.80 mm/year), the west coast river basin of South Africa (−0.360 mm/year), and the Northern Africa region (1.07 mm/year) show the lowest annual rainfall trends. There is a statistically significant increase in the rainfall in the countries of Africa's northern and central regions, while there is no statistically significant change in the countries of the southern and eastern regions. In terms of climate zones, in the tropical northern desert climates, tropical northern peninsulas, and tropical grasslands, there is a significant increase in rainfall over the entire timeframe of the month, season, and year. This implies that increased rainfall will have a positive effect on the food security of the countries in those climatic zones. Since a large percentage of Africa's agriculture is based only on rainfall (i.e., rain-fed agriculture), increasing trends in rainfall can assist climate resilience and adaptation, while declining rainfall trends can badly affect it. This information can be crucial for decision-makers concerned with effective crop planning and water resource management. The rainfall variability and trend analysis of this study provide important information to decision-makers that need to effectively mitigate drought and flood risk. [ABSTRACT FROM AUTHOR]

This is the second part of a two part series studying simulation characteristics of the Community Climate System Model, version 4 (CCSM4) for various monsoon regimes around the global tropics. Here, the West African, East African, North American, and South American monsoons are documented in CCSM4. Comparisons are made to an Atmospheric Model Intercomparison Project (AMIP) simulation of the atmospheric component in CCSM4 (CAM4), to deduce differences in the monsoon simulations run with observed SSTs and with ocean-atmosphere coupling. These simulations are also compared to a previous version of the coupled model (CCSM3) to evaluate progress. In most, but not all instances, monsoon rainfall is too heavy in the uncoupled AMIP run with the Community Atmosphere Model, version 4 (CAM4), and monsoon rainfall amounts are generally better simulated with ocean coupling in CCSM4. Some aspects of the monsoon simulations are improved in CCSM4 compared to CCSM3. Early-season rainfall in the West African monsoon is better simulated in CAM4 than in CCSM4 presumably because of the specification of SSTs in the Gulf of Guinea, but the Sahel rainfall season is captured better in CCSM4 as are the African easterly jet and the tropical easterly jet. Improvements in the simulation of the Sahel rainy season (July, August, and September) in CCSM4 compared with CCSM3 are significant, but problems remain in the simulation of the early season (May and June) in association with the misrepresentation of eastern Atlantic (Gulf of Guinea) SSTs. Precipitation distributions and the southwesterly low-level inflow in the North American monsoon are improved in CCSM4 compared to CCSM3. Both CAM4 and CCSM4 reproduce the seasonal evolution of rainfall over the South American monsoon region, but the location of maximum rainfall is misplaced to the northeast in both models. [ABSTRACT FROM AUTHOR]

This study aims to elucidate the phylogeography of the murid rodent Praomys misonnei and to document whether or not rain forest refugia and rivers structure patterns of diversity within this species. Tropical Africa, from Ghana to Kenya. Patterns of genetic structure and signatures of population history (cytochrome b gene) were assessed in a survey of 229 individuals from 54 localities. Using maximum likelihood, Bayesian, network and genetic structure analyses, we inferred intra-specific relationships and tested hypotheses for historical patterns of gene flow within P. misonnei. Our phylogenetic analyses reveal a strong phylogeographical structure. We identified four major geographical clades within P. misonnei: one clade in Ghana and Benin, a Nigerian clade, a West Central African clade and a Central and East African clade. Several subclades were identified within these four major clades. A signal of population expansion was detected in most clades or subclades. Coalescence within all of the major clades of P. misonnei occurred during the Middle Pleistocene and/or the beginning of Late Pleistocene. Our results suggest a role for both Pleistocene refugia and rivers in structuring genetic diversity in P. misonnei. This forest-dwelling rodent may have been isolated in a number of forest fragments during arid periods and expanded its range during wetter periods. Potential forest refugia may have been localized in Benin-Ghana, south-western Cameroon, southern Gabon, northern Gabon and eastern Democratic Republic of Congo-western Uganda. The Niger and/or the Cross Rivers, the Oubangui-Congo, Sanaga, Ogooue and/or Ivindo Rivers probably stopped the re-expansion of the species from relict areas. [ABSTRACT FROM AUTHOR]

The heather Erica arborea L. is a dominant element of the circum-Mediterranean region. Its broad, disjunct distribution, ranging from Macaronesia to eastern Africa, is consistent with the fragmentation of the evergreen tropical and subtropical forests that dominated Europe and North Africa in the Tertiary. This study aims to investigate phylogeographical patterns in E. arborea and to determine whether the current disjunct distribution of the species is a relict of a once wider distribution, or a recent range expansion in response to the establishment of suitable conditions. Mediterranean, Macaronesia, North and eastern Africa. A total of 105 samples were collected across the species' distribution range and sequenced at four cpDNA loci ( atpB -rbcL, matK, trnH- psbA and rpl16). Phylogenetic reconstructions, molecular dating techniques and Bayesian ancestral area reconstructions were used in combination with population genetic statistics (haplotype diversity, N, F, Fu's F) to describe the pattern of present genetic diversity in E. arborea and infer its biogeographical history. Haplotype diversity in Macaronesia and the east and central Mediterranean is much lower than that observed in eastern Africa/Arabia and the western Mediterranean. Bayesian ancestral area reconstructions and molecular dating suggest that E. arborea colonized the Mediterranean westwards from eastern Africa/Arabia at least twice during a time period ranging between the upper Miocene and the upper Pleistocene. The phylogeography of E. arborea involves a complex history of range expansions and contractions, which has resulted in a pattern of distribution that mimics that expected for a Tertiary vicariance event. Despite the presence of a late Tertiary refugium in the Iberian Peninsula, the current distribution of the species throughout the Mediterranean is explained by a Pleistocene expansion originating from eastern Africa. One explanation for the isolation of the Iberian refugium is the rapidity of the most recently identified colonization wave, as inferred by the absence of global phylogeographical signal in the data and significantly negative values of Fu's F statistic for European populations. Macaronesia was colonized during each of these two expansion waves, confirming that the laurisilva (laurel forest flora) is a complex entity including both ancient relicts and recent colonizers. [ABSTRACT FROM AUTHOR]

Palms are iconic plants. Oil palms are very important economically and originate in Africa where they can act as a model for palms in general. The effect of future climate on the growth of oil palm will be very detrimental. Latitudinal migration of tropical crops to climate refuges may be impossible, and longitudinal migration has only been confirmed for oil palm, of all the tropical crops. The previous method to determine the longitudinal trend for oil palm used the longitudes of various countries in Africa and plotted these against the percentage suitable climate for growing oil palms in each country. An increasing longitudinal trend was observed from west to east. However, the longitudes of the countries were randomly distributed which may have introduced bias and the procedure was time consuming. The present report presents an optimised and systematic procedure that divided the regions, as presented on a map derived from a CLIMEX model, into ten equal sectors and the percentage suitable climates for growing oil palm were determined for each sector. This approach was quicker, systematic and straight forward and will be useful for management of oil palm plantations under climate change. The method confirmed and validated the trends reported in the original method although the suitability values were often lower and there was less spread of values around the trend. The values for the CSIRO MK3.0 and MIROC H models demonstrated considerable similarities to each other, contributing to validation of the method. The procedure of dividing maps equally into sectors derived from models, could be used for other crops, regions, or systems more generally, where the alternative may be a more superficial visual examination of the maps. Methods are required to mitigate the effects of climate change and stakeholders need to contribute more actively to the current climate debate with tangible actions. • Optimised model confirms longitudinal trend to suitable climate for African oil palm. • The model also confirms decrease in future suitable climate for African oil palm. • Optimised model is more systematic and straight forward. • Procedure could be employed for future climate maps for other crops and other systems. • Procedure could be applied to other geographical regions. [ABSTRACT FROM AUTHOR]

Bacteria are frequently studied due to their involvement in pollutants transformation processes during wastewater treatment. In this study, the treatment efficiency, bacteria densities and their vertical profile were investigated in pilot-scale vertical flow constructed wetlands (VFCW) planted with different plant species under a tropical climate in west Africa. Five beds were planted with local plant species, i.e., Andropogon gayanus, Chrysopogon zizanioides, Echinochloa pyramidalis, Pennisetum purpureum and Tripsacum laxum, while one bed remained unplanted. These species have been rarely used in CWs while some (e.g., T. laxum) are tested for the first time. After a 7-month trial, bacteria densities were measured in substrate samples separated into six layers along the bed depth. Plants presence enhanced the bacterial density and VFCW efficiency; the removal rates of organic matter (90.9–95.9%; COD and 95.2–98.5%; BOD5), nitrogen (74.3–84%; TN and 76–84%; NH4-N) and phosphorus (77.4–96.9%; PO4-P) were higher by 5.9–24.1% compared to the control bed, providing an overall excellent treatment performance for a single-stage VFCW system. Small numbers of anaerobic bacteria were obtained in the VFCWs, explaining the low-to-zero NO3-N removal, except for the VFCWs with T. laxum and P. purpureum. Aerobic bacteria decreased from the upper to bottom layers from 17.4 to 0.1 × 106 CFU/g in the planted beds, while anaerobic bacteria increased from 0.1 to 2.1 × 106 CFU/g. Anaerobic bacteria were more abundant in the unplanted than in the planted beds. The total bacteria count was dominated by aerobic bacteria, and decreased from the surface towards the bottom. Overall, the VFCW with P. purpureum demonstrated the highest efficiency, indicating that this design is an effective and sustainable nature-based solution for wastewater treatment in a tropical climate. [ABSTRACT FROM AUTHOR]

The influence of ENSO on intraseasonal variability over the Tanzanian coast during the short (OND) and long (MAM) rainy seasons is examined. In particular, variability in the rainfall onset, peak and end dates as well as dry spells are considered. In general, El Niño appears to be associated with above average rainfall while La Niña is associated with below average rainfall over the northern Tanzanian coast during OND, and to lesser extent MAM. Over the southern coast, the ENSO impacts are less coherent and this region appears to be a transition zone between the opposite signed impacts over equatorial East and southern Africa. The increased north coast rainfall during El Niño years is generally due to a longer than normal rainfall season associated with early onset while reduced rainfall during La Niña years tends to be associated with a late onset, and thus a shorter than average rainfall season. Wet conditions during El Niño years were associated with enhanced convection and low-level easterly anomalies over the equatorial western Indian Ocean implying enhanced advection of moisture from the Indian Ocean while the reverse is true for La Niña years. Hovmöller plots for OLR and zonal wind at 850 hPa and 200 hPa show eastward, westward propagating and stationary features over the Indian Ocean. It was observed that the propagating features were absent during strong El Niño years. Based on the Hovmöller results, it is observed that the convective oscillations over the Tanzanian coast have some of the characteristic features of intraseasonal oscillations occurring elsewhere in the tropics. [ABSTRACT FROM AUTHOR]

Large mammal herbivores are important drivers of plant evolution and vegetation patterns, but the extent to which plant trait and ecosystem geography currently reflect the historical distribution of extinct megafauna is unknown. We address this question for South and Central America (Neotropical biogeographic realm) by compiling data on plant defence traits, climate, soil, and fire, as well as on the historical distribution of extinct megafauna and extant mammal herbivores. We show that historical mammal herbivory, especially by extinct megafauna, and soil fertility explain substantial variability in wood density, leaf size, spines and latex. We also identified three distinct regions (''antiherbiomes''), differing in plant defences, environmental conditions, and megafauna history. These patterns largely matched those observed in African ecosystems, where abundant megafauna still roams, and suggest that some ecoregions experienced savanna-to-forest shifts following megafauna extinctions. Here, we show that extinct megafauna left a significant imprint on current ecosystem biogeography., (© 2022. The Author(s).)

Tropical Montane Cloud Forests (TMCFs) form biodiverse communities that are characterized by frequent occurrence of low-level clouds from which they capture a substantial proportion of their precipitation — here referred to as occult precipitation. TMCFs provide important ecosystem services, in particular the supply of water to their wider surroundings. Throughout the tropics (here 23.5∘ S to 23.5∘ N), they are under pressure from deforestation and poor land management which leads to loss of both forest area and species diversity, and reduces their capture of occult precipitation. Climate change may also reduce occult precipitation in TMCFs since the cloud base may lift in response to higher temperatures — the 'lifting cloud-base hypothesis'. These threats to TMCFs are well understood, but their quantitative assessment is hampered by 1) uncertainty in the location and spatial extent of TMCFs and 2) limited availability of representative meteorological data. We use a Random Forest Classifier — informed by topographic data, MODIS vegetation data, TRMM precipitation data and ERA5-Land and MERRA-2 reanalysis products — to estimate the spatial distribution and extent of TMCFs (2.1 × 106 km2 ± 0.5 × 106 km2). We analyze temporal changes in climate, tree-cover and greenness of TMCFs over the past two to four decades to detect 1) multi-decadal trends, and 2) associations with the El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Evidence for the 'lifting cloud-base hypothesis' in reanalysis products was inconsistent across the tropics; a lifting of the cloud base during the past four decades occurred for about 20% of TMCFs, predominantly in the Americas and a few locations in Africa, while in Asia a downward movement of the cloud base was found. However, these results in part depend on the bias correction applied to the reanalyses. Changes in TMCF tree cover and greenness varied by continent; in Africa in 50% of TMCFs tree cover declined, whereas TMCFs in the Americas and in Asia exhibited a net increase in tree cover, despite a reduction in tree cover in ~20% of these TMCFs. An important limitation of the tree-cover data is that they do not distinguish between natural tree cover and agro-forestry. ENSO signals were more strongly present in precipitation in American and Asian TMCFs, whereas IOD signals were stronger in TMCF temperature and dewpoint temperature across the tropics. ENSO and IOD signals were approximately equally important for precipitation in African TMCFs and in cloud-base height across the tropics. An arbitrary warming of 1 ∘C and a 100 m lifting of the cloud base, in accordance with the 'lifting cloud hypothesis', imposed on the Random Forest classifier showed a decline in the extent of TMCFs in the Americas and Africa, but an increase in Asia — mostly at the expense of evergreen broadleaf forests. The greater vulnerability of TMCFs in Africa may be linked to their more isolated and scattered distribution across the continent and drier conditions compared to a more continuous distribution and wetter conditions in the Americas and Asia. • Estimated locations of tropical montane cloud forests with a Random Forest classifier. • Tree cover was most reduced in African TMCFs. • A lifting cloud base affected TMCFs in the Americas, a few in Africa and none in Asia. • ENSO affected precipitation in American and Asian TMCFs. • IOD affected surface and dewpoint temperatures in TMCFs across the tropics. [ABSTRACT FROM AUTHOR]

Tropical forests store 40-50 per cent of terrestrial vegetation carbon 1 . However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests 2 . Owing to climatic and soil changes with increasing elevation 3 , AGC stocks are lower in tropical montane forests compared with lowland forests 2 . Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4 megagrams of carbon per hectare (95% confidence interval 137.1-164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network 4 and about 70 per cent and 32 per cent higher than averages from plot networks in montane 2,5,6 and lowland 7 forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa 8 . We find that the low stem density and high abundance of large trees of African lowland forests 4 is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to help to guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse 9,10 and carbon-rich ecosystems., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Fine roots constitute a significant component of the net primary productivity (NPP) of forest ecosystems but are much less studied than aboveground NPP. Comparisons across sites and regions are also hampered by inconsistent methodologies, especially in tropical areas. Here, we present a novel dataset of fine root biomass, productivity, residence time, and allocation in tropical old-growth rainforest sites worldwide, measured using consistent methods, and examine how these variables are related to consistently determined soil and climatic characteristics. Our pantropical dataset spans intensive monitoring plots in lowland (wet, semi-deciduous, and deciduous) and montane tropical forests in South America, Africa, and Southeast Asia (n = 47). Large spatial variation in fine root dynamics was observed across montane and lowland forest types. In lowland forests, we found a strong positive linear relationship between fine root productivity and sand content, this relationship was even stronger when we considered the fractional allocation of total NPP to fine roots, demonstrating that understanding allocation adds explanatory power to understanding fine root productivity and total NPP. Fine root residence time was a function of multiple factors: soil sand content, soil pH, and maximum water deficit, with longest residence times in acidic, sandy, and water-stressed soils. In tropical montane forests, on the other hand, a different set of relationships prevailed, highlighting the very different nature of montane and lowland forest biomes. Root productivity was a strong positive linear function of mean annual temperature, root residence time was a strong positive function of soil nitrogen content in montane forests, and lastly decreasing soil P content increased allocation of productivity to fine roots. In contrast to the lowlands, environmental conditions were a better predictor for fine root productivity than for fractional allocation of total NPP to fine roots, suggesting that root productivity is a particularly strong driver of NPP allocation in tropical mountain regions., (© 2021 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

There is a debate concerning the definition and extent of tropical dry forest biome and vegetation type at a global spatial scale. We identify the potential extent of the tropical dry forest biome based on bioclimatic definitions and climatic data sets to improve global estimates of distribution, cover, and change. We compared four bioclimatic definitions of the tropical dry forest biome-Murphy and Lugo, Food and Agriculture Organization (FAO), DryFlor, aridity index-using two climatic data sets: WorldClim and Climatologies at High-resolution for the Earth's Land Surface Areas (CHELSA). We then compared each of the eight unique combinations of bioclimatic definitions and climatic data sets using 540 field plots identified as tropical dry forest from a literature search and evaluated the accuracy of World Wildlife Fund tropical and subtropical dry broadleaf forest ecoregions. We used the definition and climate data that most closely matched field data to calculate forest cover in 2000 and change from 2001 to 2020. Globally, there was low agreement (< 58%) between bioclimatic definitions and WWF ecoregions and only 40% of field plots fell within these ecoregions. FAO using CHELSA had the highest agreement with field plots (81%) and was not correlated with the biome extent. Using the FAO definition with CHELSA climatic data set, we estimate 4,931,414 km2 of closed canopy (≥ 40% forest cover) tropical dry forest in 2000 and 4,369,695 km2 in 2020 with a gross loss of 561,719 km2 (11.4%) from 2001 to 2020. Tropical dry forest biome extent varies significantly based on bioclimatic definition used, with nearly half of all tropical dry forest vegetation missed when using ecoregion boundaries alone, especially in Africa. Using site-specific field validation, we find that the FAO definition using CHELSA provides an accurate, standard, and repeatable way to assess tropical dry forest cover and change at a global scale., Competing Interests: The authors have declared that no competing interests exist.