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Geography and availability of natural habitat determine whether cropland intensification or expansion is more detrimental to biodiversity
Get PDFTo mitigate biodiversity loss from agriculture, intensification is often promoted as an alternative to farmland expansion. However, its local impacts remain debated. We assess globally the responses of three biodiversity metrics—species richness, total abundance and relative community abundance-weighted average range size (RCAR), a proxy for biotic homogenization—to land conversion and yield increases. Our models predict a median species loss of 11% in primary vegetation in modified landscapes, and of 25% and 40% in cropland within natural and modified landscapes, respectively. Land conversion also reduces abundance and increases biotic homogenization, with impacts varying by geographic region and history of human modification. However, increasing yields changes biodiversity as well, including in adjacent primary vegetation, with effects dependent on crop, region, biodiversity metric and natural habitat cover. Ultimately, neither expansion nor intensification consistently benefits biodiversity. Intensification has better species richness outcomes in 29%, 83%, 64% and 57% of maize, soybean, wheat and rice landscapes, respectively, whereas expansion performs better in the remaining areas. In terms of abundance and RCAR, both expansion and intensification can outperform the other depending on landscape. Therefore, minimizing local biodiversity loss requires a context-dependent balance between expansion and intensification, while avoiding expansion in unmodified landscapes
Global Methane Budget 2000–2020
Get PDFUnderstanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. CH4 is the second most important human-influenced greenhouse gas in terms of climate forcing after carbon dioxide (CO2), and both emissions and atmospheric concentrations of CH4 have continued to increase since 2007 after a temporary pause. The relative importance of CH4 emissions compared to those of CO2 for temperature change is related to its shorter atmospheric lifetime, stronger radiative effect, and acceleration in atmospheric growth rate over the past decade, the causes of which are still debated. Two major challenges in quantifying the factors responsible for the observed atmospheric growth rate arise from diverse, geographically overlapping CH4 sources and from the uncertain magnitude and temporal change in the destruction of CH4 by short-lived and highly variable hydroxyl radicals (OH). To address these challenges, we have established a consortium of multidisciplinary scientists under the umbrella of the Global Carbon Project to improve, synthesise, and update the global CH4 budget regularly and to stimulate new research on the methane cycle. Following Saunois et al. (2016, 2020), we present here the third version of the living review paper dedicated to the decadal CH4 budget, integrating results of top-down CH4 emission estimates (based on in situ and Greenhouse Gases Observing SATellite (GOSAT) atmospheric observations and an ensemble of atmospheric inverse-model results) and bottom-up estimates (based on process-based models for estimating land surface emissions and atmospheric chemistry, inventories of anthropogenic emissions, and data-driven extrapolations). We present a budget for the most recent 2010–2019 calendar decade (the latest period for which full data sets are available), for the previous decade of 2000–2009 and for the year 2020.
The revision of the bottom-up budget in this 2025 edition benefits from important progress in estimating inland freshwater emissions, with better counting of emissions from lakes and ponds, reservoirs, and streams and rivers. This budget also reduces double counting across freshwater and wetland emissions and, for the first time, includes an estimate of the potential double counting that may exist (average of 23 Tg CH4 yr−1). Bottom-up approaches show that the combined wetland and inland freshwater emissions average 248 [159–369] Tg CH4 yr−1 for the 2010–2019 decade. Natural fluxes are perturbed by human activities through climate, eutrophication, and land use. In this budget, we also estimate, for the first time, this anthropogenic component contributing to wetland and inland freshwater emissions. Newly available gridded products also allowed us to derive an almost complete latitudinal and regional budget based on bottom-up approaches.
For the 2010–2019 decade, global CH4 emissions are estimated by atmospheric inversions (top-down) to be 575 Tg CH4 yr−1 (range 553–586, corresponding to the minimum and maximum estimates of the model ensemble). Of this amount, 369 Tg CH4 yr−1 or ∼ 65 % is attributed to direct anthropogenic sources in the fossil, agriculture, and waste and anthropogenic biomass burning (range 350–391 Tg CH4 yr−1 or 63 %–68 %). For the 2000–2009 period, the atmospheric inversions give a slightly lower total emission than for 2010–2019, by 32 Tg CH4 yr−1 (range 9–40). The 2020 emission rate is the highest of the period and reaches 608 Tg CH4 yr−1 (range 581–627), which is 12 % higher than the average emissions in the 2000s. Since 2012, global direct anthropogenic CH4 emission trends have been tracking scenarios that assume no or minimal climate mitigation policies proposed by the Intergovernmental Panel on Climate Change (shared socio-economic pathways SSP5 and SSP3). Bottom-up methods suggest 16 % (94 Tg CH4 yr−1) larger global emissions (669 Tg CH4 yr−1, range 512–849) than top-down inversion methods for the 2010–2019 period. The discrepancy between the bottom-up and the top-down budgets has been greatly reduced compared to the previous differences (167 and 156 Tg CH4 yr−1 in Saunois et al. (2016, 2020) respectively), and for the first time uncertainties in bottom-up and top-down budgets overlap. Although differences have been reduced between inversions and bottom-up, the most important source of uncertainty in the global CH4 budget is still attributable to natural emissions, especially those from wetlands and inland freshwaters.
The tropospheric loss of methane, as the main contributor to methane lifetime, has been estimated at 563 [510–663] Tg CH4 yr−1 based on chemistry–climate models. These values are slightly larger than for 2000–2009 due to the impact of the rise in atmospheric methane and remaining large uncertainty (∼ 25 %). The total sink of CH4 is estimated at 633 [507–796] Tg CH4 yr−1 by the bottom-up approaches and at 554 [550–567] Tg CH4 yr−1 by top-down approaches. However, most of the top-down models use the same OH distribution, which introduces less uncertainty to the global budget than is likely justified.
For 2010–2019, agriculture and waste contributed an estimated 228 [213–242] Tg CH4 yr−1 in the top-down budget and 211 [195–231] Tg CH4 yr−1 in the bottom-up budget. Fossil fuel emissions contributed 115 [100–124] Tg CH4 yr−1 in the top-down budget and 120 [117–125] Tg CH4 yr−1 in the bottom-up budget. Biomass and biofuel burning contributed 27 [26–27] Tg CH4 yr−1 in the top-down budget and 28 [21–39] Tg CH4 yr−1 in the bottom-up budget.
We identify five major priorities for improving the CH4 budget: (i) producing a global, high-resolution map of water-saturated soils and inundated areas emitting CH4 based on a robust classification of different types of emitting ecosystems; (ii) further development of process-based models for inland-water emissions; (iii) intensification of CH4 observations at local (e.g. FLUXNET-CH4 measurements, urban-scale monitoring, satellite imagery with pointing capabilities) to regional scales (surface networks and global remote sensing measurements from satellites) to constrain both bottom-up models and atmospheric inversions; (iv) improvements of transport models and the representation of photochemical sinks in top-down inversions; and (v) integration of 3D variational inversion systems using isotopic and/or co-emitted species such as ethane as well as information in the bottom-up inventories on anthropogenic super-emitters detected by remote sensing (mainly oil and gas sector but also coal, agriculture, and landfills) to improve source partitioning.
The data presented here can be downloaded from https://doi.org/10.18160/GKQ9-2RHT (Martinez et al., 2024)
Analyzing the use of fact-checking tools in disaster-risk reduction in Europe through the lens of the heuristic-systematic model
Get PDFJournalists, emergency responders, and the general public facing natural and anthropogenic disasters frequently disseminate emergency information via social media. The spread of fake news during disasters can, however, disrupt the crisis management process and increase victim numbers. Identifying false information can curb its spread and reduce its impact on people’s attitudes and behaviors. Understanding how and why people in a disaster situation use fact-checking tools is crucial, as disaster-risk messages containing false content can usually be detected using systematic or heuristic processing. This study applies the heuristic-systematic model (HSM) to analyze social media users’ intention to use fact-checking tools. The empirical study data derived from 202 questionnaires collected through an online survey of residents of countries of the European Union. The results of structural equation modeling show the credibility of using HSM to analyze the intention to use fact-checking tools. About 33% of the changes in people’s intention to use fact-checking tools are predicted by this model. This study has implications for the use of theoretical models in communication science to predict intention to use fact-checking tools in disaster risk-reduction situations
The Debate over Falling Fertility
Get PDFA decline in global population later this century may threaten human progress, or it may lead to better live
Meeting climate target with realistic demand-side policies in the residential sector
No full textThe European Union (EU) has established an ambitious policy framework for demand-side mitigation in buildings towards net-zero targets. Here, we conduct a comprehensive quantitative assessment of 384 demand-side policy combinations for residential space heating that complement supply-side decarbonization efforts. We show that implementing the EU Emissions Trading System 2, even when combined with energy supply decarbonization, falls short of climate targets. Beyond the EU Emissions Trading System 2, we emphasize the need for ambitious heat-pump subsidies as a critical component of a successful strategy. Conversely, a large-scale generic ‘Renovation Wave’ contributes modestly to decarbonization, is not a cost-effective strategy at the EU level and requires significant public spending increases. We advocate for the implementation of a carbon tax, paired with substantial heat-pump subsidies and targeted incentives for home insulation by country and building. This approach supports the decarbonization of the residential sector, limits the strain on the electricity grid and alleviates energy poverty
Gaps and strategies for accurate simulation of waterlogging impacts on crop productivity
No full textTowards Clean Air in Nepal: Benefits, Pollution Sources, and Solutions
Get PDFHazardous air pollution poses significant health and economic challenges for Nepal. Air pollution raises public health concerns in Nepal, particularly in the country’s two geographic hotspots: the Kathmandu Valley and the Terai (southern plain areas bordering India). In these two areas, the annual average particulate matter (PM) (i.e. PM of less than 2.5 micrometers in diameter, which is the most critical air pollutant) concentrations reach 37 and 39 µg/m3, respectively. This exposure is between seven to eight times higher than the World Health Organization (WHO) guideline value of 5 µg/m3. These levels of air pollution shorten the average life expectancy of Nepal’s residents by more than three years, and lead to almost 26,000 premature deaths each year. Beyond health impacts, poor air quality leads to reduced labor productivity and negatively impacts tourism (lower visibility of the Himalayas and cancelled flights). Overall, poor air quality is estimated to cost the equivalent of more than six percent of Nepal’s gross domestic product (GDP) each year. The main objectives of this report are to identify the levels, patterns, and sources of air pollution in Nepal, assess its health and economic impacts, and present solutions to improve air quality. The recommendations are based on a foundational diagnostic review of Nepal’s existing air quality management actions. The report aims to provide comprehensive insights and actionable policy options for the government, stakeholders, and the public to support urgent and effective interventions
Family-work history and inequalities in old-age cognition in China
Get PDFPrior work showed that an individual's history of partnership, fertility, or employment was separately linked to old-age cognition, but little is known about how family-work history influences later-life cognition, especially in low- and middle-income countries. Our sample comprised respondents aged 50 and above in 2014 interviewed in regular (2011, 2013, 2015, 2018, and 2020) and life-history (2014) waves of the China Health and Retirement Longitudinal Study (CHARLS, n = 8,535). After conducting sequence analysis and identifying six statistically justifiable and context-attuned family-work trajectories, we investigated how Chinese older adults' family-work history (age 18–50) related to their cognition measured by immediate word recall (0–10) and mental status scores (0–11) cross-sectionally (pairwise comparison) and longitudinally (linear mixed-effects models). We found that older adults in the "early marriage, ≥2 children, agriculturally employed" trajectory had lowest baseline immediate recall and mental status scores compared with whom slower declines in immediate recall rather than mental status were found for those in "late marriage, ≥2 children, agriculturally employed (b = 0.02, 95 % confidence interval (CI): 0.00, 0.03)", "married, ≥2 children, not in labour force (mainly early retirees, b = 0.04, 95 % CI: 0.01, 0.06)", and "married, ≥2 children, non-agriculturally employed in public sector (b = 0.04, 95 % CI: 0.03, 0.06)" trajectories. Our findings imply that inequalities in China's pre-1964 birth cohorts' cognition were affected by marriage timing and, to a greater extent, driven by midlife employment sectors which determined substantial inequalities in access to social welfare
Assessment of Drought Impacts in the Ebro Basin Using Hydro-Economic Modeling and Copula-Based Water Availability Simulations
No full textClimate change will exacerbate drought events in arid and semiarid basins, with longer and more intense drought spells. This will further jeopardize the sustainability of water systems in these basins, augmenting the uncertainty of streamflows and the risks of large economic and environmental damages. Hydro-economic modeling has been used already in the literature for analyzing the impacts of reduced water availability from climate change. However, previous studies do not consider the change in the scale of drought duration and intensity. This study closes this gap by combining hydro-economic analysis with a procedure based on copulas, where the copula procedure generates future climate water stress conditions with longer and more intense droughts. In this work, the joint probability function of two consecutive monthly water inflows is fitted by a Clayton copula, an asymmetric copula that captures the lower tail dependence implicit in drought persistence. Then, the hydro-economic model is used to analyze the economic impacts of climate change in the Ebro Basin of Spain. The reliability, resilience, and vulnerability of the water system are evaluated in order to assess the sustainability of the Ebro basin. Results show that there are costs of maladaptation when changes in drought duration and intensity from climate change are ignored, where maladaptation costs ensue from erroneous drought planning. Measures for drought management would be flawed because of the inaccurate evaluation of climate change hazards, given that the temporal dependence of climate variables is overlooked