Future Greenhouse Gas Emissions Research Articles

Climate Change Mitigation in Thailand’s Domestic Aviation: Mitigation Options Analysis towards 2050

Thailand’s civil aviation industry has expanded rapidly in the past ten years resulting in increasing aviation greenhouse gas (GHG) emissions and energy consumption. The rapid growth in air transport is anticipated to continue further. Presently, domestic aviation and the economy of many countries are recovering rapidly in the post-COVID-19 period, resulting in fuel consumption and GHG emissions gradually increasing again. However, despite implementing the ICAO’s CORSIA (International Civil Aviation Organization’s Carbon Offsetting and Reduction Scheme for International Aviation) rule for international aviation, GHG emissions in the domestic aviation sector are largely unregulated. Moreover, the literature lacks a GHG emissions analysis that considers this sector’s potential growth and mitigation policies for future GHG emissions. To close the gap, this study conducted a GHG emissions analysis from this sector under various scenarios through 2050 using historical data during 2008–2020 to forecast future trends. It evaluates the impact of the mitigation policies, such as fuel switching and aircraft technology, on improving fuel efficiency due to technological advancements in aircraft and carbon pricing. The results show that the fuel switching option would result in a significant long-term reduction in GHG emissions, whereas the carbon pricing option and aircraft technology option are desirable in reducing GHG emissions in the short term. Therefore, to meet GHG emissions reduction targets more successfully, all measures must be simultaneously executed to address short- and long-term mitigation strategies. These findings have significant implications for both present and future GHG emissions reduction measures, supporting Thailand’s 2050 climate targets and energy efficiency policies as the domestic aviation industry adjusts.

Shareholder Activism on Climate Change: Evolution, Determinants, and Consequences

We study 944 shareholder proposals submitted to 343 U.S. firms on climate change issues during 2009–2022. We use logistic and two-stage regression to estimate the propensity for a firm to be targeted or subjected to a vote at the annual general meeting and, for voted proposals, the determinants of that vote. We also examine whether climate-related proposals affect investor returns and how they relate to firms’ future environmental performance and greenhouse gas emissions. Compared to a matched sample, we first find that activists target larger, more carbon-intensive, and less R&D-active firms. Second, voting likelihood is higher for firms with repeated and operations-related proposals and lower pre-proposal environmental ratings. By contrast, disclosure-related proposals are likelier to be negotiated and withdrawn. Third, repeated and operations-related proposals receive higher votes in favor, whereas votes on carbon-intensive firms do not. Fourth, building on the theory that investors act as if they distinguish among the different shareholder proposals based on the expected cost to the firm, we find evidence to support this idea. We find that investors respond negatively to ex-ante costlier proposals, such as those that relate to emissions reduction and target carbon-intensive firms. Fifth, targets’ future environmental performance rating is almost twenty percent higher after a proposal than before compared to the matched sample, whereas emissions do not budge appreciably.

Soil Water Regime, Air Temperature, and Precipitation as the Main Drivers of the Future Greenhouse Gas Emissions from West Siberian Peatlands

This modeling study intended to solve a part of the global scientific problem related to increased concentrations of carbon dioxide in the atmosphere via emissions from terrestrial ecosystems that, along with anthropogenic emissions, make notable contributions to the processes of climate change on the planet. The main stream of CO2 from natural terrestrial ecosystems is related to the activation of biological processes, such as the production/destruction of plant biomass. In this study, the Wetland-DNDC computer simulation model with a focus on nitrogen and carbon biogeochemical cycles was used to study the effect of hydrothermal conditions on greenhouse gas fluxes in West Siberian peatlands. The study was implemented on the site of the world’s largest pristine wetland/peatland system, the Great Vasyugan Mire (GVM). The study was carried out based on data from permanent measurements at meteo stations and our own in situ measurements of hydrological and thermal parameters on sites, which allowed for testing different scenarios of changes in environmental conditions (temperature, precipitation, groundwater level) together with a change in GHG fluxes. The study revealed the air temperature and the level of groundwater as the main drivers controlling CO2 fluxes. The study of different scenarios of change in annual air temperature revealed the threshold of change in the wetland/peatland ecosystem from carbon sink to carbon source to the atmosphere to happen with an increase in the average annual air temperature by 3 °C with reference to the average annual air temperature values in 2019. Also, we found that the wetland/peatland ecosystem turned to act as an active carbon sink with about 7 cm increase in annual groundwater level, compared with its base level of −21 cm.

Global risk of heat stress to cattle from climate change

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.

Adaptation to multi-meter sea-level rise should start now

Abstract Sea-level rise will fundamentally change coastal zones worldwide. A global two meters rise of sea level will be exceeded sooner or later within a time window ranging from one century to as long as two millennia, depending on future greenhouse gas emissions and polar ice-sheet melting. Here, we show that in addition to climate mitigation to slow the rise, adaptation to two meters of sea-level rise should start now. This involves changing our mindset to define a strategic vision for these threatened coastal areas and identify realistic pathways to achieve this vision. This can reduce damages, losses, and lock-ins in the future, identify problems before they become critical and exploit opportunities if they emerge. To meet this challenge, it is essential that coastal adaptation becomes core to coastal development, especially for long-lived critical infrastructure. Coastal adaptation will be an ongoing process for many decades and centuries, requiring the support of climate services, which make the links between science, policy and adaptation practice.

Future climate change in the Agulhas system and its associated impact on South African rainfall

South African climate variability has been linked to changes in both the Agulhas system and external forcing (i.e. CO2 and ozone). We analysed future climate change in the Agulhas system volume transport and its associated impacts on South Africa’s precipitation using the Community Climate System Model version 4 as part of the Coupled Model Intercomparison Project, phase 5. Output from one historical and three future greenhouse gas emission scenarios were examined to project various climate storylines. We found that the Agulhas Current volume transport decreases across all three scenarios and that the current displays a strong baroclinic component with an increase in transport at the surface and decrease at intermediate depths. Agulhas leakage was found to increase with historical emissions. Additionally, an east-west dipole pattern for convective precipitation was found over South Africa, with an increase over the eastern region related to an increase in greenhouse gas emissions and a decrease in the western region linked to the location of Hadley cell edge latitude. Moving into the 21st century, future predictions in regional climate variability are shown to be dependent on the intensity of greenhouse gas emissions and are extremely important for South Africa, a region prone to drought and flooding and home to a large population dependent on rain-fed agriculture. Significance: Future climate variability in the Agulhas system and South African region is heavily dependent on changes in external forcing. The Agulhas Current volume transport decreases as the greenhouse gas emissions continue to increase and a strong baroclinic component is found with an increase in transport at the surface and a decrease at the intermediate depths. A strong east-west dipole precipitation pattern is found over South Africa with the increase in the eastern region related to the increase in greenhouse gas emissions and the decrease in the western region related to the location of the Hadley cell edge latitude.

Integrating a choice experiment into an agent-based model to simulate climate-change induced migration: The case of the Mekong River Delta, Vietnam

Forecasting the future impact of climate change on migration is difficult, for many reasons, including the interactive and dynamic nature of many decisions and the heterogeneity of behavior. One popular solution, agent-based models (ABM) cope well with dynamics and heterogeneity, but often lack rigorous foundations in terms of individual behavior. Moreover, given limited exposure to actual climate change, it can be a challenge to build adequate behavioral models of migration choice based on historical data. To tackle this issue, we build an ABM of future migration using a bespoke choice experiment (CE) designed to examine intention to migrate among farmers living in the Vietnamese Mekong Delta (VMD). In the CE, respondents are asked to make migration choices for scenarios constructed using six attributes: drought intensity, flood frequency, income gain from migration, migration networks, neighbors' choice, and crop choice restriction. The simulation runs to 2050 and is based on two scenarios of future global emissions of greenhouse gases—Representative Concentration Pathway (RCP) 4.5 and RCP8.5. The results suggest potentially high levels of migration as a result of climate change and the particular importance of positive feedback from pre-existing migration and neighbor's choices. The results also suggest that crop-restriction regulations have a significant impact on migration for coastal provinces of VMD. Finally, we find that migration drivers vary significantly across provinces, which suggests the policymakers point to targeted action for each province. In summary, the study demonstrates how integrating CE into ABM can foster the predictive modeling of climate-induced migration.

Climate indices as predictors of global soil organic carbon stocks

ABSTRACT Global soils store more carbon than the atmosphere and terrestrial vegetation combined, with a significant proportion located in colder regions. Earth system models incorporating climate-carbon feedback suggest that a warming climate can potentially destabilize soil carbon storage, leading to carbon release into the atmosphere. However, existing models are based on limited measurements of soil organic carbon (SOC) loss and a comprehensive global-scale climate indices that effectively characterizes climate-SOC relationships is currently lacking. In this study, we present a synthetic analysis that evaluates the effectiveness of different climate indices in estimating SOC stocks using a global compilation of SOC data and the Boltzmann Sigmoidal Model (BSM). Our findings reveal that a climate index, defined as TD - Index = exp ( − 0.002 T − 0.8 D ) , where T and D are mean century temperature (MCT) and dryness respectively, serves as the most reliable predictor for SOC stocks. Furthermore, we observed temperature tipping points for SOC, ranging from −4.5 to −3°C for different soil layers. As the temperature transitions from being below to above the tipping point, the SOC shifts from a stable, high state to a rapid decline. An analysis of the projected temperatures for SOC under various future greenhouse gas emissions scenarios showed a northward shift in the northern hemisphere, potentially opening up vast areas of arctic territory to increased SOC loss from the soils, with corresponding emissions of the stored carbon into the atmosphere. Our findings open up new avenues for research on and management strategies for climate-related SOC dynamics.

Crepidium ridleyi (J.J.Sm.) Szlach., a threatened endemic terrestrial orchid of Java: A Maxent modeling to predict the current and future potential distribution

Crepidium ridleyi (J.J.Sm.) Szlach. is one of the endemic terrestrial orchids from Java. Due to rapid development and habitat fragmentation, it faces a severe threat of extinction. In this study, we predict the specific habitat of C. ridleyi within Java Island using the future greenhouse gas emission scenarios of RCP 4.5 and RCP 8.5 for the years 2050 and 2070. The occurrences were found in protected sites but have yet to be conserved in ex-situ sites. The current and future of this species distribution model comparison showed that habitat suitability is declining, even projecting the extinction in the worst scenario in the far future. Thus, supporting active conservation efforts for this species is strongly advised to protect it from extinction and use it sustainably.

Distortion of sectoral roles in climate change threatens climate goals

The longstanding method for reporting greenhouse gas emissions—carbon dioxide equivalence (CO2e)—systematically underestimates methane-dominated economic sectors' contributions to warming in the coming decades. This is because it only calculates the warming impact of a pulse of emissions over a 100-year period. For short-lived climate forcers that mostly influence the climate for a decade or two, like methane, this method masks their near-term potency. Assessing the impacts of future greenhouse gas emissions using a simple climate model reveals that midcentury warming contributions of sectors dominated by methane—agriculture, fossil fuel production and distribution, and waste—are two times higher than estimated using CO2e. The CO2e method underemphasizes the importance of reducing emissions from these sectors, and risks misaligning emissions targets with desired temperature outcomes. It is essential to supplement CO2e-derived insights with approaches that convey climate impacts of ongoing emissions over multiple timescales, and to never rely exclusively on CO2e.

Current and projected patterns of warming and marine heatwaves in the Southern Indian Ocean

The Southern Indian Ocean (20–120°E, 70–30°S) hosts an exceptional biodiversity that contributed to the inscription of the French and Australian natural reserves on the UNESCO World Heritage List. This region is a “hot spot” for ocean heat uptake and already experiences intense marine heat waves (MHW), as evidenced in 2011/2012 over the Kerguelen Plateau. In the coming decades, this region is also expected to face supplemental anthropogenic warming, depending on future greenhouse gas emissions, with unknown consequences for its marine ecosystems. Here, we present a regional analysis of ocean warming and MHW based on the analyses of historical observations and Coupled Model Intercomparison Project Phase 6 (CMIP6) climate projections. Consistent with observations over the last decades, we find an intensification through the 21st century of surface warming and MHW over a band located between 40°S and 55°S within the Antarctic Circumpolar Current region. CMIP6 models also project much faster climate velocities (i.e. the speed and direction at which isotherms drift in the wake of climate change) in the mesopelagic (200–1000 m) than at the surface (0–200 m). Lastly, a comparison between the two Shared Socioeconomic Pathways (SSP1-2.6 and SSP2-4.5) analysed in this study shows much larger changes in the second half of the 21st century for the higher emission scenario. These results suggest that the subantarctic islands will probably be mostly affected by warming and MHW under both scenarios, although committing to SSP1-2.6 could substantially alleviate the pressure on ecosystems in the long term. This study also highlights the need to consider a tri-dimensional environment that may evolve at different paces when designing efficient conservation measures.

The sea level simulator v1.0: a model for integration of mean sea level change and sea level extremes into a joint probabilistic framework

Abstract. A statistical model called the sea level simulator v1.0 is introduced. The model integrates mean sea level change and sea level extremes into a joint probabilistic framework that is useful for coastal spatial planning. Given a user-defined planning period, the model can estimate the flood risk as a function of height above the current mean sea level. These flood risk estimates are derived through Monte Carlo simulations of a very large number of planning periods. The derived flood risk is contingent on user-assigned probabilities for future greenhouse gas emission pathways, and the model is thus also useful for quantifying the dependence of flood risk on such pathways and their probabilities. Moreover, the simulator can quantify whether flood risk is dominated by sea level extremes or mean sea level rise and how this depends on the length of the planning period. The code, written in MATLAB, is parallelized and lightweight enough that it can be run on an ordinary PC. The code is easily adaptable to include new locations, new mean sea level projections and similar model developments. The flood risk estimates derived from the simulator are well suited to tackle adaptation and decision problems. Applications for construction of coastal protection and land development in coastal areas have been demonstrated in the past. The paper gives an in-depth technical description of the model. Example simulations from a Swedish nuclear site are also given, and the capabilities of the simulator are discussed. The main aim of the paper is to work as a technical reference for the first public release of the sea level simulator.

Japan’s greenhouse gas reduction scenarios toward net zero by 2050 in the material cycles and waste management sector

The first draft scenario toward net zero greenhouse gas (GHG) emissions by 2050 for the material cycles and waste management sector was presented by the Ministry of the Environment, Japan in August 2021. The details of the future GHG emission estimation used to create the draft scenario are described in this document. For multiple scenarios where more aggressive measures, such as carbon capture, utilization, and storage (CCUS), were included in addition to business-as-usual and the current policy continuity scenario, future GHG emissions were estimated as the sum of the products of activities and emission factors indicating changes in measures between scenarios. The estimation outcomes demonstrated that future GHG emissions from the solid waste management sector could be anticipated to be zero or even negative when material conversion to biomass, primarily for plastics, recycling to raw materials, and installation of CCUS at incineration facilities are assumed. Extensions of prior plans are not enough to reach the goal of net zero emissions, according to the measures necessary and the volume and pace of their implementation suggested in this study. Stakeholders should collaborate with great ambition.

Physics-Based Prediction for the Consumption and Emissions of Passenger Vehicles and Light Trucks up to 2050

The increasing market share of electric vehicles and the politically intended phase-out of the internal combustion engine require reliable and realistic predictions for future consumption and greenhouse gas emissions as a function of technological solutions. This also includes the consumption- and emission-intensive transport of goods. We consider both passenger vehicles and commercial vehicle traffic in our study and have investigated whether there are drive alternatives to the battery electric vehicle that enable uninterrupted trips with a long range, especially for regional delivery services and internationally active freight forwarders. To this end, we have analysed three system architectures and their expected technological progress until 2050: battery electric vehicles (BEV), fuel cell electric vehicles (FCEV), and internal combustion engine vehicles (ICEV) running on compressed natural gas (CNG). The latter case serves as a best-practice reference from a combustion technology perspective. The analysis is based on a validated and proven physical model and predicts that the BEV2050 will consume 3.5 times less energy and emit 15 times fewer greenhouse gases than the ICEV-CNG2020, whereas the FCEV2050 will consume 2.5 times less energy and emit 6.5 times fewer greenhouse gases than the ICEV-CNG2020 on the road (hilly terrain, transition season, and WLTP triple-mixed drive cycle). The advantages of the BEV result from the shorter drive train with lower total losses. Our results thus confirm the expected role of the BEV as the dominant drive technology in the future, and light vehicles with low-to-medium-range requirements will especially benefit from it. On the other hand, since the greenhouse gas emissions of the FCEV2050 are lower by a factor of 6.5 than those of the ICEV-CNG2020, it is reasonable to conclude that the FCEV can play a significant role in transport until 2050 when long distances have to be covered. Our model-based approach also allows us to determine the energy fractions of the acting physical forces and thus calculate the consumption shares: electric drive recuperation increases BEV and FCEV range by about 15% in 2020 and will increase it by about 20% in 2050, depending on drive technology and vehicle type. Air and rolling resistance contribute 20% each to the total consumption. The consumption of the accessories of modern vehicles with a share of about 10% of the total consumption cannot be neglected.

Climate change scenarios in fisheries and aquatic conservation research

AbstractScenarios are central to fisheries and aquatic conservation research on climate change. Scenarios project future greenhouse-gas emissions, which climate models translate into warming projections. Recent climate research and global development trends have significantly changed our understanding of plausible emissions pathways to 2100 and climate sensitivities to emissions. Here, we review these developments and make recommendations for scenario use in fisheries and aquatic conservation research. Although emissions pathways are uncertain, recent research suggests that scenarios producing ∼3.4–4.5 W/m2 radiative forcing by 2100 (e.g. scenarios SSP2-3.4 and SSP2-4.5/RCP4.5) might be most plausible. This corresponds to ∼2–3 degrees C global warming by 2100 with median climate sensitivities, or 1.5–4 degrees C considering climate-system uncertainties. Higher- and lower-emissions scenarios (e.g. RCP2.6 and RCP6.0) might be plausible and should be explored in research. However, high-emission scenarios (RCP8.5/SSP5-8.5, SSP3-7.0) seem implausible and should be used with clear rationales and caveats to ensure results are not misinterpreted by scholars, policymakers, and media. We analyse fisheries and aquatic conservation papers published from 2015 to 2022 in major journals, and find that RCP8.5/SSP5-8.5 are the most commonly used scenarios, though RCP4.5/SSP2-4.5 use has increased since 2020. Studies predominantly project quantitative rather than qualitative differences between these scenarios’ impacts.

Strategic Climate Change Litigation and the EU Habitats Directive: Squaring the Circle with the Help of the U.S. Endangered Species Act?

Abstract Against the backdrop of the rising temperatures and the existing ‘emission gap’, climate change lawsuits have recently emerged as a new lever in order to step up compliance with international reduction targets. As of today, the majority of these strategic lawsuits are based upon tort law and human rights duties, which is evident given the major impact unhalted climate change on the immediate survival chances of future generations of humans. However, many terrestrial as well as marine ecosystems are already suffering from the global rise of temperatures, also in Europe. This article addresses the principal question as to whether within the specific context of the European Union, climate change litigation could not also use the 1992 Habitats Directive as an complementary instrument to mitigate future greenhouse gas emissions or at least prepare and adapt ecosystems for the inevitable impact of climate change. Using the recent courtroom experiences with the U.S. Endangered Species Act (ESA) of 1973 in the context of climate change-related lawsuits as a benchmark, this article argues that global warming will be an increasingly important factor when applying the conservation duties of the Habitats Directive in the coming decades.

Greenhouse gas emissions and peak trend of commercial vehicles in China

Commercial vehicles are important within the context of global warming, since they exhibit greenhouse gas (GHG) emissions that are disproportionate to their quantity. The aim of this study was to create a bottom-up GHG emissions assessment model which considers GHG emissions of newly produced commercial vehicles and those in current use. Through this study, the number of future commercial vehicles were predicted, thereby facilitating a simulation of future GHG emissions. Our results show that the total GHG emissions of commercial vehicles in 2019 was 580 million t CO2-eq.. Among them, the GHG emissions stemming from the production of new commercial vehicles accounted for ∼0.3% of the emissions, whereas the use stage accounted for more than 99.0%. Moreover, the future ownership of commercial vehicles depends on GDP and the demand of freight and passenger transport. The ownership of commercial vehicles was predicted about 36.61 million in 2025, 45.44 million in 2030 and 55.85 million in 2035. The carbon peak of commercial vehicles varies across different scenarios, peaking around 2031–2034, at 680–780 million t CO2-eq.. This study systematically simulated the carbon peak of commercial vehicles, contributing toward a deeper understanding of commercial vehicles within the context of GHG emissions. These results can be applied toward creating quantitatively-driven pathways for carbon peak or neutrality targets in the commercial vehicle sector.

Global greenhouse gases emissions effect on extreme events under an uncertain future: A case study in Western Cape, South Africa

The growing effect of CO2 and other greenhouse gas (GHG) emissions on the extreme climate risks in the Western Cape, South Africa, calls for the need for better climate adaptation and emissions-reduction strategies to protect the region’s long-term social-economic benefits. This paper presents a comprehensive evaluation of changes in the future extreme events associated with drought and heatwave under three different greenhouse gas (GHG) emissions scenarios: Representative Concentration Pathway (RCP) 2.6, RCP 4.5, and RCP 8.5, from moderate to severe, respectively. Various diagnostic indices were used to determine how future heatwaves and drought will respond to each different RCP climate scenario in Western Cape based on Max Planck Institute-Earth System Model/REMO (MPI-ESM/REMO). The projected simulation results revealed that drought and heatwave extreme climate indices suggest strong relationships between future extreme climate risks and GHG emissions for Western Cape, South Africa. Anthropogenic activities and growing GHG emissions will lead to severer extreme climate stress in terms of drought and the duration, frequency, and magnitude of heatwave stresses. As a result, we believe that reducing the GHG emissions to alleviate future extreme climate stress becomes a practical solution to protect the local’s socio-economic system and further maintain the region’s economic prosperity.

Galyean appreciation club review: a holistic perspective of the societal relevance of beef production and its impacts on climate change.

This article provides a science-based, data-driven perspective on the relevance of the beef herd in the U.S. to our society and greenhouse gas (GHG) contribution to climate change. Cattle operations are subject to criticism for their environmental burden, often based on incomplete information disseminated about their social, economic, nutritional, and ecological benefits and detriments. The 2019 data published by the U.S. Environmental Protection Agency reported that U.S. beef cattle emitted 22.6% of the total agricultural emissions, representing about 2.2% of the total anthropogenic emissions of CO2 equivalent (CO2e). Simulations from a computer model developed to address global energy and climate challenges, set to use extreme improvements in livestock and crop production systems, indicated a potential reduction in global CO2e emissions of 4.6% but without significant enhancement in the temperature change by 2030. There are many natural and anthropogenic sources of CH4 emissions. Contrary to the increased contribution of peatlands and water reservoirs to atmospheric CO2e, the steady decrease in the U.S. cattle population is estimated to have reduced its methane (CH4) emissions by about 30% from 1975 to 2021. This CH4 emission deacceleration of 2.46 Mt CO2e/yr2 might be even more significant than reported. Many opportunities exist to mitigate CH4 emissions of beef production, leading to a realistic prospect of a 5% to 15% reduction in the short term after considering the overlapping impacts of combined strategies. Reduction strategies include feeding synthetic chemicals that inactivate the methyl-coenzyme M reductase (the enzyme that catalyzes the last step of methanogenesis in the rumen), red seaweed or algae extracts, ionophore antibiotics, phytochemicals (e.g., condensed tannins and essential oils), and other nutritional manipulations. The proposed net-zero concept might not solve the global warming problem because it will only balance future anthropogenic GHG emissions with anthropogenic removals, leaving global warming on a standby state. Recommendations for consuming red meat products should consider human nutrition, health, and disease and remain independent of controversial evidence of causational relationships with perceived negative environmental impacts of beef production that are not based on scientific data.

Cylinder Pressure Feedback Control for Ideal Thermodynamic Cycle Tracking: Towards Self-learning Engines

To meet increasingly strict future greenhouse gas and pollutant emission targets, development time and costs of heavy-duty internal combustion engines will reach unacceptable levels. This is mainly due to increased system complexity and need to guarantee robust performance under a wide range of real-world conditions. Cylinder Pressure Based Control is a major contributor to achieve these goals in advanced, highly-efficient engine concepts. Current Cylinder Pressure Based Control approaches use combustion and air-path parameters as feedback signals. These signals are not directly linked to engine efficiency; therefore, compensation for changing ambient conditions, engine ageing or differences in fuel qualities is a non-trivial problem. Contrary to other methods, the method presented in this paper aims to realise an idealised thermodynamic cycle by directly control of the entire cylinder pressure curve. From measured in-cylinder pressure, a new set of feedback signals is derived using principle component decomposition. With these signals, optimal fuel path settings are determined. The potential of this method is demonstrated for a dual fuel Reactivity Controlled Compression Ignition (RCCI) engine, which combines very high efficiency and ultra low nitrogen oxides and particle matter emission. For the studied RCCI engine, it is shown that the newly proposed optimisation method gave the same optimal fuel path settings as existing methods. This is an important step towards self-learning engines.