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Harmonizing nature’s timescales in ecosystem models
Get PDFModeling complex, nonlinear ecosystem processes across different timescales presents a significant challenge. We identify two key issues: selecting a representative timestep that captures interconnected processes across various timescales, and simulating these processes in an appropriate sequence. By synthesizing existing ecosystem frameworks, we find shared compromises between biological realism and computational performance. For the representative timestep, these include ‘selective elimination of timescales’, ‘biting the bullet’, ‘each in their own time’, and ‘capture the unseen’. For processing order, we identify hierarchical, logical, iterative, and random approaches. Similar challenges exist in other disciplines, and we show how transferring methods from multiple fields, along with smarter computing, can improve timescale integration. Overcoming these challenges requires innovative transdisciplinary solutions, and we outline directions for future research
Impact of Dams on Salinity Intrusion and Agricultural Productivity: Evidence from Mekong River
Get PDFThe paper examines how upstream dam construction impacts freshwater levels downstream, affecting salinity intrusion and agricultural productivity in the delta. The study combines historical records of dam construction on the Mekong River, water level observations, and agricultural productivity statistics, with satellite data as proxies for salinity index and vegetation coverage. The findings show that increased reservoir capacity significantly reduces downstream freshwater discharge, decreases rice yield, and intensifies saltwater intrusion, while annual electricity output partially mitigates these effects. These impacts are most severe during dry seasons and closer to the shore. Two mechanisms are identified: the disruptive but temporary ”filling effect” in the first-year post-dam completion, and the persistent, smaller ”operational effect” over time
Co-benefits of efficient and climate friendly cooling in China
Get PDFThe cooling sector plays a pivotal role in the global economy but significantly contributes to global warming. In 2022, cooling-related emissions accounted for 13% of global greenhouse gas (GHG) emissions. China, in particular, played a substantial role in cooling accounting for 10% of its national emissions and consuming 15% of its total electricity. This substantial environmental impact stems largely from the sector's reliance on refrigerants with high Global Warming Potential (GWP) and energy-intensive equipment. The refrigeration and air conditioning sector widely adopted hydrofluorocarbons (HFCs) as replacements for ozone-depleting substances regulated under the Montreal Protocol. However, as potent GHG, HFCs significantly contribute to global warming and are now subject to a global phase-down under the Kigali Amendment to the Montreal Protocol. Improving the energy efficiency of cooling equipment alongside the phasedown of HFCs could potentially double the mitigation benefits of the Kigali Amendment. With the growing demand for cooling in China, it is essential to explore mitigation strategies that simultaneously reduce HFC emissions and enhance energy efficiency. This study evaluates the co-benefits of efficient and climate-friendly cooling solutions in China.
This study adopts a bottom-up approach to integrate the Refrigeration and Air Conditioning - Demand, Emission, and Cost (RAC-DEC) model with Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) models. The research focuses on four key cooling subsectors: room air conditioning, mobile air conditioning, commercial air conditioning, and cold chain. The analysis is conducted under three scenarios: Business-as-Usual (BAU), reflecting current policies and practices; Kigali Amendment with enhanced energy efficiency of cooling equipment (KAE); and Accelerated Transformational Energy Efficiency (ATE). This study projects medium- and long-term trends in refrigerant and energy consumption, driven by key demand drivers for each subsector. It then quantifies both direct refrigerant emissions following the IPCC inventory methodology and indirect emissions from energy consumption. Finally, it evaluates the combined emission reduction potential under the alternative KAE and ATE scenarios.
The preliminary results indicate that among China's cooling sector, the commercial refrigeration sector offers the highest potential for emission reduction, accounting for approximately 40% of the total cumulative emission reductions from 2023 to 2060. By 2060, China’s cooling sector could achieve cumulative emission reductions of approximately 11.5 Gt CO₂-eq in the KAE scenario and 16.5 Gt CO₂-eq in the ATE scenario. In the KAE scenario, emissions are expected to decline by 48% from 2022 to 2050. In contrast, the ATE scenario predicts a 70% reduction in annual emissions, dropping from 714–721 Mt CO₂-eq in 2022 to 217–218 Mt CO₂-eq by 2050. These significant reductions are primarily driven by the accelerated phase-out of HFC refrigerants, enhanced energy efficiency, and the deep decarbonization of the power system.
This study underscores the critical role of the cooling sector in contributing to global climate goals, including the COP28 Global Cooling Pledge and the Kigali Amendment. By providing a methodological framework, our findings offer essential scientific support for policymakers in China and beyond, facilitating coordinated efforts to actively reduce fluorinated GHGs and enhance energy efficiency within the cooling sector
An ecological perspective to master the complexities of the digital economy
Get PDFEconomic and social interactions are shifting to digital platforms which grow into vast ecosystems where user engagement creates value for members while ecosystem orchestrators harvest massive revenue. The digital ecosystem business model succeeds by adeptly navigating fast-changing environments, including new technologies and volatile demands, through dynamic innovation in a decentralized decision-making setting. This renders digital platform ecosystems complex adaptive systems. Recognizing that natural ecosystems are a prime example of complex adaptive systems, we propose a systematic hierarchical framework for describing and understanding digital ecosystems, rooted in ecology and evolution. Our framework compares digital ecosystems hosted by societies to natural ecosystems embedded in biomes, products to species, and technologies and elements of business strategy to the genetic makeup of a species. As digital platforms face heightened scrutiny about their socio-economic power and societal value, our approach contributes to the development of deeper understanding and sustainable governance of the digital economy
Conflicting stakeholder priorities produce sustainability tradeoffs for cereal production in Northeast China
Get PDFNortheast China (NEC) as one of the primary breadbaskets of China plays an essential role in achieving sustainable agriculture to provide sufficient and nutritious food while minimizing resource consumption and environmental costs. Growing evidence indicates crop switching is a promising solution for achieving sustainable agriculture. Comprehensively assessing synergies and tradeoffs among competing objectives for stakeholders is essential for crop switching implementation but not well documented in NEC. We examine tradeoffs and synergies among multi-objectives—nutritional yields, water demand, greenhouse gas emissions (GHGs), and benefits—from policymakers’ and farmers’ perspectives for cereals in NEC using the most recent data available, and assess potential sustainability changes from implementing the policy of crop switching. We find no single cereal can achieve all objectives of sustainable agriculture in most regions of NEC for stakeholders and synergies and tradeoffs have obviously spatial heterogeneity. Overall, rice has the best performance on energy and protein yield but the worst on iron yield, water requirement, and GHGs. Coarse cereals (sorghum and millet) have better desirable attributes on iron yield 223% and 66% more, blue water requirement 91% and 90% less, and GHGs 84% less than rice, but not for energy and protein yield because of lower yields. From the farmers’ perspective, rice can produce more revenue than dryland cereals by 32%–58% due to higher price and yield. Nevertheless, the sustainability of cereal production in NEC will be improved from crop switching with a 33% increment in iron production, a 24% and 3% decrease in irrigation water demand and GHGs, and a 4% increment in farmers’ revenue on existing cultivation area without compromises in rice production. Our study indicates that comprehensively assessing the synergies and tradeoffs among multiple objectives and stakeholders will provide more opportunities to align policymakers with practitioners to make crop switching feasible and achieve sustainable agriculture
Traceable and Scalable Food Balance Sheets from Agricultural Commodity Supply and Utilization Accounts (2010–2022)
Get PDFThe Food Balance Sheets (FBS), compiled by the Food and Agriculture Organization (FAO), serve as a cornerstone dataset for studies on agricultural development, food security, and dietary health, providing a broad overview of global and regional food systems. However, its limited transparency and scalability hinder its application in empirical analysis and multisector dynamic modeling. Here, we present a traceable Food Balance Sheets (T-FBS) dataset, developed from detailed Supply Utilization Accounts (SUA) using a novel Primary Commodity equivalent (PCe) aggregation approach. This framework enables the aggregation of commodity flows along supply chains while ensuring consistency and balance across multiple dimensions. The T-FBS dataset includes 57 PCe commodities across 195 regions for the period 2010–2022, consolidated from over 500 SUA products. While T-FBS closely aligns with FAO-FBS at aggregate levels for dietary energy and macronutrients, it identifies key uncertainties in other elements (e.g., feed, trade, stocks). By enhancing methodological transparency, traceability, and scalability, T-FBS strengthens the robustness of food system studies and fosters future research and collaboration within the open-source community
Managing nitrogen to achieve sustainable food-energy-water nexus in China
Get PDFNitrogen holds a crucial place in sustaining the food-energy-water (FEW) nexus, which underpins human society. Its importance spans food production, energy generation, and water quality preservation. Here we show that comprehensive nitrogen management strategies offer the dual benefits of satisfying China's food requirements and boosting nitrogen energy production from straw by 1 million tonnes (26%) compared to 2020. Simultaneously, these strategies could lead to a reduction of 8 million tonnes (-31%) in nitrogen fertilizer usage, a decrease of 3.8 million tonnes (-46%) in nitrogen-induced water pollution, and a halving of water consumption in agriculture, all relative to 2020 levels. These transformative changes within the FEW nexus could result in national societal gains of around US8 billion. This highlights the cost-effectiveness of such strategies and their potential to support China's sustainable development goals, especially in hunger relief, clean energy, and aquatic ecosystem protection
Irreversible glacier change and trough water for centuries after overshooting 1.5 °C
Get PDFExceeding 1.5 °C of global warming above pre-industrial levels has become a distinct possibility, yet the consequences of such an overshoot for mountain glaciers and their contribution to raising sea levels and impacting water availability are not well understood. Here we show that exceeding and then returning to below 1.5 °C will have irreversible consequences for glacier mass and runoff over centuries. Global climate and glacier simulations project that a 3.0 °C peak-and-decline scenario will lead to 11% more global glacier mass loss by 2500 compared with limiting warming to 1.5 °C without overshooting. In basins where glaciers regrow after peak temperature, glacier runoff reduces further than if the glaciers stabilize, a phenomenon we call ‘trough water’. Half the studied glaciated basins show reduced glacier runoff with overshoot compared with without for decades to centuries after peak warming. These findings underscore the urgency of near-term emissions reductions and limiting temperature overshoot
Tracking green space along streets of world cities
Get PDFStreet green space (SGS) - the presence of vegetation along streets of cities—is a key piece of urban infrastructure. SGS provides a broad range of functions, such as mitigating the urban heat island effect, reducing the impact of extreme precipitation events, and supporting human and animal well-being. Here we introduce an approach to estimate SGS based on the statistical modeling of a street-based indicator of canopy coverage (the green view index, GVI) with multispectral satellite observations and ancillary spatially granular data. Based on our trained and cross-validated non-parametric model, we conduct spatial sampling and prediction in 190 large cities distributed across twenty regions and estimate local to continental GVI trends between 2016–2023. Jointly considering such global pool of cities, we find evidence of a trend of GVI decrease of 0.3%–0.5% per year ( p < 0.01 ) . Yet, both the direction and magnitude of trends show high heterogeneity across and within regions and cities, which we explore, along with stark inequalities in SGS availability within each city. Our analysis provides an updated estimate of the GVI as a measure of SGS across a global pool of cities and an open-source, validated approach to assess its future changes and support the design of policies for sustainable cities