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Same data, different analysts: variation in effect sizes due to analytical decisions in ecology and evolutionary biology
Get PDFAlthough variation in effect sizes and predicted values among studies of similar phenomena is inevitable, such variation far exceeds what might be produced by sampling error alone. One possible explanation for variation among results is differences among researchers in the decisions they make regarding statistical analyses. A growing array of studies has explored this analytical variability in different fields and has found substantial variability among results despite analysts having the same data and research question. Many of these studies have been in the social sciences, but one small “many analyst” study found similar variability in ecology. We expanded the scope of this prior work by implementing a large-scale empirical exploration of the variation in effect sizes and model predictions generated by the analytical decisions of different researchers in ecology and evolutionary biology. We used two unpublished datasets, one from evolutionary ecology (blue tit, Cyanistes caeruleus, to compare sibling number and nestling growth) and one from conservation ecology (Eucalyptus, to compare grass cover and tree seedling recruitment). The project leaders recruited 174 analyst teams, comprising 246 analysts, to investigate the answers to prespecified research questions. Analyses conducted by these teams yielded 141 usable effects (compatible with our meta-analyses and with all necessary information provided) for the blue tit dataset, and 85 usable effects for the Eucalyptus dataset. We found substantial heterogeneity among results for both datasets, although the patterns of variation differed between them. For the blue tit analyses, the average effect was convincingly negative, with less growth for nestlings living with more siblings, but there was near continuous variation in effect size from large negative effects to effects near zero, and even effects crossing the traditional threshold of statistical significance in the opposite direction. In contrast, the average relationship between grass cover and Eucalyptus seedling number was only slightly negative and not convincingly different from zero, and most effects ranged from weakly negative to weakly positive, with about a third of effects crossing the traditional threshold of significance in one direction or the other. However, there were also several striking outliers in the Eucalyptus dataset, with effects far from zero. For both datasets, we found substantial variation in the variable selection and random effects structures among analyses, as well as in the ratings of the analytical methods by peer reviewers, but we found no strong relationship between any of these and deviation from the meta-analytic mean. In other words, analyses with results that were far from the mean were no more or less likely to have dissimilar variable sets, use random effects in their models, or receive poor peer reviews than those analyses that found results that were close to the mean. The existence of substantial variability among analysis outcomes raises important questions about how ecologists and evolutionary biologists should interpret published results, and how they should conduct analyses in the future
Probabilistic Trade‐Offs Analysis for Sustainable and Equitable Management of Climate‐Induced Water Risks
Get PDFPressures on water resources are fueling conflicts between sectors. This trend will likely worsen under future climate-induced water stress, jeopardizing food, energy and human water security in most arid and semi-arid regions. Probabilistic analysis using stochastic optimization modeling can characterize multi-sector vulnerabilities and risks associated with future water stress. This study identifies the probabilistic trade-offs between agricultural, urban and energy sectors in the Ebro Basin (Spain). Two intervention policies have been examined and compared: (a) agricultural priority, and (b) energy priority, for two planning horizons 2040–2070 and 2070–2100. Results show that the human water security goal is achieved under both intervention policies. However, the achievement of the food and energy security goals depends on the policy objectives and on the spatial location of irrigation schemes and hydropower plants, which result in different stream flows across the basin. The policy choice results in substantially different benefit gains and losses by sector and therefore by location. None of the sectoral production priority policy provides an equitable sharing of benefits among all sectors and locations under climate change, which is an important issue, because the success or failure of policy interventions would depend on the distribution of the gains and losses of benefits across the basin. Policy uptake by stakeholders would depend on reaching win-win outcomes where losers are compensated, while delivering acceptable levels of food, energy and human water security in large river basins. Information on the probabilistic trade-offs contributes to the design of water management strategies capable of addressing the multi-sector vulnerability
Herding resilience: Surveys and Bayesian spatial models for Africa’s livestock
Get PDFThis paper proposes a novel method for mapping livestock distribution in Africa using the Living Standards Measurement Study-Integrated Surveys on Agriculture (LSMS-ISA). Using a Bayesian spatial statistical model, we produce maps of livestock distribution at a resolution of 1 km2. Our case study in Malawi, covering 2010 and 2019, demonstrates the effectiveness of the method in mapping five livestock species. We compare our results with the Gridded Livestock of the World (GLW) database and use the maps to assess livestock vulnerability to climate-related flood risks under different climate scenarios. This approach provides a rapid, data-rich tool for policy makers to assess climate risks to livestock, which is critical for sustainable agricultural development and environmental management in data-poor regions
Global Carbon Budget 2024
Get PDFAccurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesise datasets and methodologies to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC) are based on land-use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based fCO2-products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. Additional lines of evidence on land and ocean sinks are provided by atmospheric inversions, atmospheric oxygen measurements and Earth System Models. The sum of all sources and sinks results in the carbon budget imbalance (BIM), a measure of imperfect data and incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ.
For the year 2023, EFOS increased by 1.3 % relative to 2022, with fossil emissions at 10.1 ± 0.5 GtC yr-1 (10.3 ± 0.5 GtC yr-1 when the cement carbonation sink is not included), ELUC was 1.0 ± 0.7 GtC yr-1, for a total anthropogenic CO2 emission (including the cement carbonation sink) of 11.1 ± 0.9 GtC yr-1 (40.6 ± 3.2 GtCO2 yr-1). Also, for 2023, GATM was 5.9 ± 0.2 GtC yr-1 (2.79 ± 0.1 ppm yr-1), SOCEAN was 2.9 ± 0.4 GtC yr-1 and SLAND was 2.3 ± 1.0 GtC yr-1, with a near zero BIM (-0.02 GtC yr-1). The global atmospheric CO2 concentration averaged over 2023 reached 419.3 ± 0.1 ppm. Preliminary data for 2024, suggest an increase in EFOS relative to 2023 of +0.8 % (-0.3 % to 1.9 %) globally, and atmospheric CO2 concentration increased by 2.8 ppm reaching 422.5 ppm, 52 % above pre-industrial level (around 278 ppm in 1750). Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2023, with a near-zero overall budget imbalance, although discrepancies of up to around 1 GtC yr-1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows: (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the mean ocean sink.
This living data update documents changes in methods and datasets applied to this most-recent global carbon budget as well as evolving community understanding of the global carbon cycle. The data presented in this work are available at https://doi.org/10.18160/GCP-2024 (Friedlingstein et al., 2024)
Impact of digital greening synergistic transformation on urban economic resilience in China: Evidence from quasi-natural experiments
Get PDFDigital greening synergistic transformation (DGST) has emerged as a crucial driver of high-quality economic development, notably enhancing urban economic resilience. This paper examines panel data from 280 Chinese cities (2008–2021) by performing quasi-natural experiments from the ‘Broadband China’ and ‘Low-Carbon Cities’ pilot initiatives and employing a multi-period difference-in-differences (DID) approach. The main findings are as follows. (1) DGST notably enhances urban economic resilience, showing stronger effects than standalone pilot projects. (2) DGST strengthens economic resilience by enhancing defence, adaptation and learning capacities through labour absorption, industrial structure optimisation and green technology innovation. (3) The effect of DGST on economic resilience is influenced by factors such as human capital, financial resources and infrastructure, with cities possessing greater resources deriving more substantial benefits. (4) Cities that implemented ‘Low-Carbon Cities’ prior to ‘Broadband China’ experienced more pronounced improvements in economic resilience. This paper underscores the synergy between digital and green policies in strengthening economic resilience and provides recommendations to advance DGST and strengthen urban economies
Support to the development of the fourth clean air outlook – Final report
Get PDFThe overall objective for this service request was to provide the underlying analysis to support the preparation of the Commission’s fourth Clean Air Outlook report. Alongside this, the outputs will also help to inform the Commission’s review of the NEC Directive due in 2025. In line with the service request, the analysis undertaken as part of this contract should help to address a series of research questions: - To what extent will the national emission reduction commitments (ERC) set in the NEC Directive be achieved for the periods 2020-29 and 2030 onwards with the implementation of the existing and proposed EU and national legislation? - To what extent will the 2030 target of the Zero Pollution Action Plan to “reduce by more than 55% compared to 2005 the health impacts (premature deaths) of air pollution” be achieved with the implementation of the existing and proposed EU and national legislation? - To what extent will the 2030 target of the Zero Pollution Action Plan to “reduce by 25% compared to 2005 the EU ecosystems where air pollution threatens biodiversity” be achieved with the implementation of the existing and proposed EU and national legislation? - What are the most effective and efficient measures per Member State to reduce ammonia emissions so as to achieve their ammonia emission reduction commitments for the periods 2020-29 and 2030 onwards and the Zero Pollution Action Plan ecosystem related target? - How has the implementation of the NEC Directive influenced air pollutant emissions in recent and current years as opposed to source legislation at EU or national level? As with previous iterations of the Clean Air Outlook, the engagement with, and involvement of, Member State experts has been critical for ensuring the analysis is robust and reflective of the situation across the EU
Estimating the sea level rise responsibility of industrial carbon producers
Get PDFGlobal mean sea levels have risen at an accelerating rate over the past century in response, primarily to greenhouse gas emissions from the combustion of fossil fuels. We use MAGICC7, a reduced complexity climate-carbon cycle model, to quantify how emissions traced to the Carbon Majors, the world’s 122 largest fossil fuel and cement producers, from 1854–2020 contributed to present-day surface air temperature rise, and sea level rise both historically and projected through 2300. We find that emissions traced to these industrial actors have contributed 37%–58% to present day surface air temperature rise and 24%–37% to the observed global mean sea level rise to date. Critically, these emissions through 2020 are expected to contribute an additional 0.26–0.55 m of global sea level rise through 2300. We find that attribution of past emissions to projected future sea level rise is robust regardless of how emissions trajectories evolve in the coming centuries
Drivers of livestock manure nitrogen recycling on county scale in China
No full textAs the world's largest livestock producer, China faces pressing challenges in recycling manure to minimize resource waste and environmental degradation resulting from the vast amounts of manure generated. Understanding the drivering forces behind manure recycling is essential for advancing sustainable agriculture in China. This study estimated the manure recycling ratio (MRR), measured by nitrogen content, across 2853 Chinese counties using data from 390,000 farms representing four major livestock farming types in 2017. Northern Chinese counties demonstrated significantly higher MRRs, with values exceeding 50 %, compared to Southern regions, with values being lower than 30 %. Higher MRRs were linked to larger cropland size, higher urbanization levels, and a greater proportion of chicken farming. In contrast, MRRs declined in regions with higher temperatures, increased precipitation, higher manure production per livestock unit, a greater emphasis on pig farming, and an ageing rural population. Notably, natural factors such as temperature and precipitation predominantly influenced MRRs in both Southern and Northern China, whereas socioeconomic factors like cropland size and urbanization were more impactful in Eastern and Southwestern regions. These findings highlight the need for region-specific strategies that account for natural and socioeconomic conditions to enhance manure recycling practices across China
Neglecting future sporadic volcanic eruptions underestimates climate uncertainty
Get PDFMost climate projections represent volcanic eruptions as a prescribed constant forcing based on a historical average, which prevents a full quantification of uncertainties in climate projections. Here we show that the contribution of volcanic forcing uncertainty to the overall uncertainty in global mean surface air temperature projections reaches up to 49% in 2029, and is comparable or greater than that from internal variability throughout the 21st century. Furthermore, compared to a constant volcanic forcing, employing a stochastic volcanic forcing reduces the probability of exceeding 1.5 °C warming above pre-industrial level by at least 5% for high climate mitigation scenario, and enhances the probability of negative decadal temperature trends by up to 8%. Intermediate to high climate mitigation scenarios are particularly sensitive to the choice of future volcanic forcing implementation. We recommend the use of either a stochastic approach or prescribed constant forcing levels that sample volcanic uncertainty in future climate simulations
Public Support for Flood Risk Management: Insights from an Italian Alpine Survey Using Systems Thinking
Get PDFThis study presents the results of a survey on flood risk awareness conducted in the Italian Alps, examining the impacts of a major weather event on public perception and trust. It develops a systems-thinking framework to analyse dynamic feedback loops influencing flood risk management support over time. The survey data collection overlapped with a severe storm event in Central Europe, the storm “Adrian” (also known as “Vaia”). This provided a unique pre- and post-event perspective. Results highlight the critical role of individual knowledge, trust in authorities, and social group dynamics in shaping risk perception processes. The study shows how major weather events can change perceptions, sense of safety, and institutional trust within local communities, and more interestingly, these changes can vary spatially. The findings are summarised using a systems-thinking framework, which helps to identify possible feedback loops between flood risk management interventions and long-term public support. The study emphasizes the importance of forward-looking, systems-thinking approaches in the design, monitoring, and evaluation of flood risk management plans. These approaches allow one to account for often-overlooked dynamics, such as spatially varying feedback loops and counter-intuitive effects, ultimately improving the long-term effectiveness of flood risk management