From Metabolism to Ecology:Cross-Feeding Interactions Shape the Balance between Polymicrobial Conflict and Mutualism

Polymicrobial interactions are widespread in nature, and play a major role in maintaining human health and ecosystems. Whenever one organism uses metabolites produced by another organism as energy or nutrient sources, this is called cross-feeding. The ecological outcomes of cross-feeding interactions are poorly understood and potentially diverse: mutualism, competition, exploitation or commensalism. A major reason for this uncertainty is the lack of theoretical approaches linking microbial metabolism to microbial ecology. To address this issue, we explore the dynamics of a one-way interspecific cross-feeding interaction, in which food can be traded for a service (detoxification). Our results show that diverse ecological interactions (competition, mutualism, exploitation) can emerge from this simple cross-feeding interaction, and can be predicted by the metabolic, demographic and environmental parameters that govern the balance of the costs and benefits of association. In particular, our model predicts stronger mutualism for intermediate by-product toxicity because the resource-service exchange is constrained to the service being neither too vital (high toxicity impairs resource provision) nor dispensable (low toxicity reduces need for service). These results support the idea that bridging microbial ecology and metabolism is a critical step towards a better understanding of the factors governing the emergence and dynamics of polymicrobial interactions

Effects of Urbanization on Native Bird Species in Three Southwestern US Cities

Urbanization presents novel challenges to native species by altering both the biotic and abiotic environment. Studies have attempted to make generalizations about how species with similar traits respond to urbanization, although existing results are idiosyncratic across cities and often fail to account for seasonality. Here, we present a comparative study in three US cities: Fresno, California; Tucson, Arizona; and Phoenix, Arizona. Using presence-absence data to define regional bird species pools and urban assemblages in non-breeding (winter) and breeding (spring) seasons, we tested whether urban avian assemblages were a random subset of regional assemblages on the basis of both traits and phylogeny, and whether urbanization was associated with homogenization among avian assemblages. We found evidence for non-random trait filtering into urban assemblages, including of diet guilds, migratory status, and primary habitat, but filtering differed across cities and seasons, being strongest for diet and in Fresno. There was no evidence for non-random phylogenetic-based filtering in urban avian assemblages. Dissimilarity in species and diet guild composition within each season was higher between cities than between regional species pools. These findings show the potential for biotic differentiation as opposed to homogenization as the outcome of environmental filtering processes operating on species traits across cities and seasons

Risks to biodiversity from temperature overshoot pathways

Temperature overshoot pathways entail exceeding a specified global warming level (e.g. 1.5°C or 2°C) followed by a decline in warming, achieved through anthropogenically enhanced CO2 removal from the atmosphere. However, risks to biodiversity from temperature overshoot pathways are poorly described. Here, we explore biodiversity risks from overshoot by synthesizing existing knowledge and quantifying the dynamics of exposure and de-exposure to potentially dangerous temperatures for more than 30 000 species for a 2°C overshoot scenario. Our results suggest that climate risk to biodiversity from temperature overshoot pathways will arrive suddenly, but decrease only gradually. Peak exposure for biodiversity occurs around the same time as peak global warming, but the rate of de-exposure lags behind the temperature decline. While the global overshoot period lasts around 60 years, the duration of elevated exposure of marine and terrestrial biodiversity is substantially longer (around 100 and 130 years, respectively), with some ecological communities never returning to pre-overshoot exposure levels. Key biodiversity impacts may be irreversible and reliance on widespread CO2 removal to reduce warming poses additional risks to biodiversity through altered land use. Avoiding any temperature overshoot must be a priority for reducing biodiversity risks from climate change, followed by limiting the magnitude and duration of any overshoot. More integrated models that include direct and indirect impacts from overshoot are needed to inform policy. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'

Climate change in South Africa: Risks and opportunities for climate-resilient development in the IPCC Sixth Assessment WGII Report

South Africa is wrestling with increasing climate change impacts and how to respond. The 2022 IPCC Working Group II Report synthesises the latest evidence on climate change impacts, vulnerability and adaptation, and what this means for climate-resilient development. In this commentary, South African authors on the Report reflect on its key findings and the implications for the country. The commentary highlights challenges and opportunities for cities, the food-water-energy-nature nexus, knowledge and capacity strengthening (which includes climate services, climate change literacy, and indigenous and local knowledge), climate finance, equity, justice and social protection, and climate-resilient development pathways. The piece closes with a reflection on research gaps requiring attention and the importance of urgently ramping up climate action to secure a liveable future for all South Africans

The role of indigenous knowledge and local knowledge in water sector adaptation to climate change in Africa: a structured assessment

Evidence is increasing of human responses to the impacts of climate change in Africa. However, understanding of the effectiveness of these responses for adaptation to climate change across the diversity of African contexts is still limited. Despite high reliance on indigenous knowledge (IK) and local knowledge (LK) for climate adaptation by African communities, potential of IK and LK to contribute to adaptation through reducing climate risk or supporting transformative adaptation responses is yet to be established. Here, we assess the influence of IK and LK for the implementation of water sector adaptation responses in Africa to better understand the relationship between responses to climate change and indigenous and local knowledge systems. Eighteen (18) water adaptation response types were identified from the academic literature through the Global Adaptation Mapping Initiative (GAMI) and intended nationally determined contributions (iNDCs) for selected African countries. Southern, West, and East Africa show relatively high evidence of the influence of IK and LK on the implementation of water adaptation responses, while North and Central Africa show lower evidence. At country level, Zimbabwe displays the highest evidence (77.8%) followed by Ghana (53.6%), Kenya (46.2%), and South Africa (31.3%). Irrigation, rainwater harvesting, water conservation, and ecosystem-based measures, mainly agroforestry, were the most implemented measures across Africa. These were mainly household and individual measures influenced by local and indigenous knowledge. Adaptation responses with IK and LK influence recorded higher evidence of risk reduction compared to responses without IK and LK. Analysis of iNDCs shows the most implemented water adaptation actions in academic literature are consistent with water sector adaptation targets set by most African governments. Yet only 10.4% of the African governments included IK and LK in adaptation planning in the iNDCs. This study recommends a coordinated approach to adaptation that integrates multiple knowledge sources, including IK and LK, to ensure sustainability of both current and potential water adaptation measures in Africa

From moral hazard to risk-response feedback

The Intergovernmental Panel on Climate Change assessments (IPCC) Special Report on 1.5 °C of global warming is clear. Nearly all pathways that hold global warming well below 2 °C involve carbon removal (IPCC, 2015). In addition, solar geoengineering is being considered as a potential tool to offset warming, especially to limit temperature until negative emissions technologies are sufficiently matured (MacMartin et al., 2018). Despite this, there has been a reluctance to embrace carbon removal and solar geoengineering, partly due to the perception that these technologies represent what is widely termed a “moral hazard”: that geoengineering will prevent people from developing the will to change their personal consumption and push for changes in infrastructure (Robock et al., 2010), erode political will for emissions cuts (Keith, 2007), or otherwise stimulate increased carbon emissions at the social-system level of analysis (Bunzl, 2008). These debates over carbon removal and geoengineering echo earlier ones over climate adaptation. We argue that debates over “moral hazard” in many areas of climate policy are unhelpful and misleading. We also propose an alternative framework for dealing with the tradeoffs that motivate the appeal to “moral hazard,” which we call “risk-response feedback.

Decolonizing climate change–heritage research

Climate change poses a threat to heritage globally. Decolonial approaches to climate change–heritage research and practice can begin to address systemic inequities, recognize the breadth of heritage and strengthen adaptation action globally.DATA AVAILABILITY STATEMENT: The underlying dataset for Fig. 1a is available open access from the supplemental material in ref. 5, and datasets for Fig. 1b,c from the UNESCO World Heritage List 2021 in ref. 32.The UK government’s Foreign, Commonwealth & Development Office and the International Development Research Centre, Ottawa, Canada; the FLAIR Fellowship Programme: a partnership between the African Academy of Sciences and the Royal Society funded by the UK government’s Global Challenges Research Fund; the Mapping Africa’s Endangered Archaeological Sites and Monuments project funded by Arcadia — a charitable fund of Lisbet Rausing and Peter Baldwin; the Leverhulme Trust Doctoral Training Scheme, hosted by Southampton Marine and Maritime Institute at the University of Southampton.https://www.nature.com/nclimatehj2023Historical and Heritage Studie

Research priorities for climate mobility

The escalating impacts of climate change on the movement and immobility of people, coupled with false but influential narratives of mobility, highlight an urgent need for nuanced and synthetic research around climate mobility. Synthesis of evidence and gaps across the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report highlight a need to clarify the understanding of what conditions make human mobility an effective adaptation option and its nuanced outcomes, including simultaneous losses, damages, and benefits. Priorities include integration of adaptation and development planning; involuntary immobility and vulnerability; gender; data for cities; risk from responses and maladaptation; public understanding of climate risk; transboundary, compound, and cascading risks; nature-based approaches; and planned retreat, relocation, and heritage. Cutting across these priorities, research modalities need to better position climate mobility as type of mobility, as process, and as praxis. Policies and practices need to reflect the diverse needs, priorities, and experiences of climate mobility, emphasizing capability, choice, and freedom of movement