As anthropogenic climate change continues the risks to biodiversity will increase over time, with future projections indicating that a potentially catastrophic loss of global biodiversity is on the ...horizon
. However, our understanding of when and how abruptly this climate-driven disruption of biodiversity will occur is limited because biodiversity forecasts typically focus on individual snapshots of the future. Here we use annual projections (from 1850 to 2100) of temperature and precipitation across the ranges of more than 30,000 marine and terrestrial species to estimate the timing of their exposure to potentially dangerous climate conditions. We project that future disruption of ecological assemblages as a result of climate change will be abrupt, because within any given ecological assemblage the exposure of most species to climate conditions beyond their realized niche limits occurs almost simultaneously. Under a high-emissions scenario (representative concentration pathway (RCP) 8.5), such abrupt exposure events begin before 2030 in tropical oceans and spread to tropical forests and higher latitudes by 2050. If global warming is kept below 2 °C, less than 2% of assemblages globally are projected to undergo abrupt exposure events of more than 20% of their constituent species; however, the risk accelerates with the magnitude of warming, threatening 15% of assemblages at 4 °C, with similar levels of risk in protected and unprotected areas. These results highlight the impending risk of sudden and severe biodiversity losses from climate change and provide a framework for predicting both when and where these events may occur.
Ecological research and practice are crucial to understanding and guiding more positive relationships between people and ecosystems. However, ecology as a discipline and the diversity of those who ...call themselves ecologists have also been shaped and held back by often exclusionary Western approaches to knowing and doing ecology. To overcome these historical constraints and to make ecology inclusive of the diverse peoples inhabiting Earth's varied ecosystems, ecologists must expand their knowledge, both in theory and practice, to incorporate varied perspectives, approaches and interpretations from, with and within the natural environment and across global systems. We outline five shifts that could help to transform academic ecological practice: decolonize your mind; know your histories; decolonize access; decolonize expertise; and practise ethical ecology in inclusive teams. We challenge the discipline to become more inclusive, creative and ethical at a moment when the perils of entrenched thinking have never been clearer.
At least 10,000 virus species have the ability to infect humans but, at present, the vast majority are circulating silently in wild mammals
. However, changes in climate and land use will lead to ...opportunities for viral sharing among previously geographically isolated species of wildlife
. In some cases, this will facilitate zoonotic spillover-a mechanistic link between global environmental change and disease emergence. Here we simulate potential hotspots of future viral sharing, using a phylogeographical model of the mammal-virus network, and projections of geographical range shifts for 3,139 mammal species under climate-change and land-use scenarios for the year 2070. We predict that species will aggregate in new combinations at high elevations, in biodiversity hotspots, and in areas of high human population density in Asia and Africa, causing the cross-species transmission of their associated viruses an estimated 4,000 times. Owing to their unique dispersal ability, bats account for the majority of novel viral sharing and are likely to share viruses along evolutionary pathways that will facilitate future emergence in humans. Notably, we find that this ecological transition may already be underway, and holding warming under 2 °C within the twenty-first century will not reduce future viral sharing. Our findings highlight an urgent need to pair viral surveillance and discovery efforts with biodiversity surveys tracking the range shifts of species, especially in tropical regions that contain the most zoonoses and are experiencing rapid warming.
Competitive exclusion and habitat filtering influence community assembly, but ecologists and evolutionary biologists have not reached consensus on how to quantify patterns that would reveal the ...action of these processes. Currently, at least 22 α‐diversity and 10 β‐diversity metrics of community phylogenetic structure can be combined with nine null models (eight for β‐diversity metrics), providing 278 potentially distinct approaches to test for phylogenetic clustering and overdispersion. Selecting the appropriate approach for a study is daunting. First, we describe similarities among metrics and null models across variance in phylogeny size and shape, species abundance, and species richness. Second, we develop spatially explicit, individual‐based simulations of neutral, competitive exclusion, or habitat filtering community assembly, and quantify the performance (type I and II error rates) of all 278 metric and null model combinations against each assembly process. Many α‐diversity metrics and null models are at least functionally equivalent, reducing the number of truly unique metrics to 12 and the number of unique metric + null model combinations to 72. An even smaller subset of metric and null model combinations showed robust statistical performance. For α‐diversity metrics, phylogenetic diversity and mean nearest taxon distance were best able to detect habitat filtering, while mean pairwise phylogenetic distance‐based metrics were best able to detect competitive exclusion. Overall, β‐diversity metrics tended to have greater power to detect habitat filtering and competitive exclusion than α‐diversity metrics, but had higher type 1 error in some cases. Across both α‐ and β‐diversity metrics, null model selection affected type I error rates more than metric selection. A null model that maintained species richness, and approximately maintained species occurrence frequency and abundance across sites, exhibited low type I and II error rates. This regional null model simulates neutral dispersal of individuals into local communities by sampling from a regional species pool. We introduce a flexible new R package, metricTester, to facilitate robust analyses of method performance.
Abstract
Considering the feasibility and effectiveness of adaptation options is essential for guiding responses to climate change that reduce risk. Here, we assessed the feasibility of adaptation ...options for the African context. Using the Global Adaptation Mapping Initiative, a stocktake of adaptation-related responses to climate change from the peer-reviewed literature in 2013–2020, we found 827 records of adaptation actions in Africa. We categorised and evaluated 24 adaptation options and for each option, six dimensions of feasibility were considered: economic, environmental, social, institutional, technological, and evidence of effectiveness. Over half (51%) of all adaptation actions were reported in the food sector where sustainable water management (SWM) was the most reported option. The fewest actions were reported for cities (5%). The majority of actions (53%) were recorded in just six countries: Ghana, Ethiopia, Kenya, Tanzania, Nigeria and South Africa. Encouragingly, effectiveness was assessed as medium or high for 95% of adaptation options. However, no options had high feasibility on any other dimension. Technological and institutional factors present major barriers to implementation. Crop management, SWM, sustainable agricultural practices, agroforestry, livelihood diversification, ecosystem governance and planning, health governance and planning, infrastructure and built environment, all had moderate feasibility across three or more dimensions. Human migration has low feasibility but high potential for risk reduction. Major knowledge gaps exist for environmental feasibility, for assessing adaptation limits at increasing levels of climate hazard, for economic trade-offs and synergies, and for Central and Northern Africa. Our results highlight sectors where enablers for adaptation can be increased. Future assessments can apply the method established here to extend findings to other national and local levels.
Under the United Nations Framework Convention on Climate Change, international financial assistance is expected to support African and other developing countries as they prepare for and adapt to the ...impacts of climate change. The impact of this finance depends on how much finance is mobilized and where it is targeted. However, there has been no comprehensive quantitative mapping of adaptation-related finance flows to African countries to date. Here we track development finance principally targeting adaptation from bilateral and multilateral funders to Africa between 2014 and 2018. We find that the amounts of finance are well below the scale of investment needed for adaptation in Africa, which is a region with high vulnerability to climate change and low adaptation capacity. Finance targeting mitigation (US$30.6 billion) was almost double that for adaptation (US$16.5 billion). The relative share of each varies greatly among African countries. More adaptation-related finance was provided as loans (57%) than grants (42%) and half the adaptation finance has targeted just two sectors: agriculture; and water supply and sanitation. Disbursement ratios for adaptation in this period are 46%, much lower than for total development finance in Africa (at 96%). These are all problematic patterns for Africa, highlighting that more adaptation finance and targeted efforts are needed to ensure that financial commitments translate into meaningful change on the ground for African communities.
Key policy insights
Between 2014 and 2018, adaptation-related finance committed by bilateral and multilateral funders to African countries remained well below US$5.5 billion per year, or roughly US$5 per person per year; these amounts are well below the estimates of adaptation costs in Africa.
Funders have not strategically targeted support for adaptation activities towards the most vulnerable to climate change African countries.
Lessons from countries that have been more successful in accessing finance point to the value of more sophisticated domestic adaptation policies and plans; of alignment with priorities of the NDC; of meeting funding requirements of specific funders; and of the strategic use of climate funds by national planners.
A low adaptation finance disbursement ratio in this period in Africa (at 46%) relates to barriers impeding the full implementation of adaptation projects: low grant to loan ratio; requirements for co-financing; rigid rules of climate funds; and inadequate programming capacity within many countries.
Animals have diversified into a bewildering variety of morphological forms exploiting a complex configuration of trophic niches. Their morphological diversity is widely used as an index of ecosystem ...function, but the extent to which animal traits predict trophic niches and associated ecological processes is unclear. Here we use the measurements of nine key morphological traits for >99% bird species to show that avian trophic diversity is described by a trait space with four dimensions. The position of species within this space maps with 70-85% accuracy onto major niche axes, including trophic level, dietary resource type and finer-scale variation in foraging behaviour. Phylogenetic analyses reveal that these form-function associations reflect convergence towards predictable trait combinations, indicating that morphological variation is organized into a limited set of dimensions by evolutionary adaptation. Our results establish the minimum dimensionality required for avian functional traits to predict subtle variation in trophic niches and provide a global framework for exploring the origin, function and conservation of bird diversity.
Abstract Cattle farming is a major source of global food production and livelihoods that is being impacted by climate change. However, despite numerous studies reporting local-scale heat impacts, ...quantifying the global risk of heat stress to cattle from climate change remains challenging. We conducted a global synthesis of documented heat stress for cattle using 164 records to identify temperature-humidity conditions associated with decreased production and increased mortality, then projected how future greenhouse gas emissions and land-use decisions will limit or exacerbate heat stress, and mapped this globally. The median threshold for the onset of negative impacts on cattle was a temperature-humidity index of 68.8 (95% C.I.: 67.3–70.7). Currently, almost 80% of cattle globally are exposed to conditions exceeding this threshold for at least 30 days a year. For global warming above 4°C, heat stress of over 180 days per year emerges in temperate regions, and year-round heat stress expands across all tropical regions by 2100. Limiting global warming to 2°C, limits expansion of 180 days of heat stress to sub-tropical regions. In all scenarios, severity of heat stress increases most in tropical regions, reducing global milk yields. Future land-use decisions are an important driver of risk. Under a low environmental protection scenario (SSP3-RCP7.0), the greatest expansion of cattle farming is projected for tropical regions (especially Amazon, Congo Basin, and India), where heat stress is projected to increase the most. This would expose over 500 million more cattle in these regions to severe heat risk by 2090 compared to 2010. A less resource-intensive and higher environmental protection scenario (SSP1-RCP2.6) reduces heat risk for cattle by at least 50% in Asia, 63% in South America, and 84% in Africa. These results highlight how societal choices that expand cattle production in tropical forest regions are unsustainable, both worsening climate change and exposing hundreds of millions more cattle to large increases in severe, year-round heat stress.
PDF
