Greenhouse Gas Emissions

The long-term goal of containing average warming below the 2  degrees C limit requires deep cuts in emissions from all sectors. The fast growing global aviation industry has committed to reduce carbon emissions. Carbon offsetting is an integral element of the sector's strategy. Already, airlines offer voluntary carbon offsetting to those customers who wish to mitigate the impact of their travel. To ensure carbon offsetting can make a meaningful and credible contribution, this paper first discusses the science behind ‘carbon offsetting’, followed by the associated policy perspective. Then, against the context of different aviation emissions pathways, the paper provides empirical evidence of current airline practices in relation to offsetting mechanisms and communication. Building on these insights, the challenges of reducing
aviation emissions and using carbon credits to compensate for ongoing growth are discussed. The paper concludes by proposing five principles of best practice for carbon offsetting that airlines can use as a basis
to develop credible emissions strategies, and that could inform the sectoral framework currently being developed by leading aviation organisations.

Due to its prevalence in modern infrastructure, concrete is experiencing the most rapid increase in consumption among globally common structural materials; however, the production of concrete results in approximately 8.6% of all anthropogenic CO2 emissions. Many methods have been developed to reduce the greenhouse gas emissions associated with the production of concrete. These methods range from the replacement of inefficient manufacturing equipment to alternative binders and the use of breakthrough technologies; nevertheless, many of these methods have barriers to implementation. In this research, we examine the extent to which the increased use of several currently implemented methods can reduce the greenhouse gas emissions in concrete material production without requiring new technologies, changes in production, or novel material use. This research shows that, through increased use of common supplementary cementitious materials, appropriate selection of proportions for cement replacement, and increased concrete design age, 24% of greenhouse gas emissions from global concrete production or 650 million tonnes (Mt) CO2-eq can be eliminated annually.

A B S T R A C T Nutrient-poor organic soils under maritime grassland are often located in remote wet locations in the landscape. Leaving these soils without drainage maintenance often raise the water table but continuous management (grazing) means they could remain a source of carbon dioxide (CO 2) while also turning into a small source of methane (CH 4). Due to geographical and socioeconomic reasons, removing these sites from agricultural production may be an option to mitigate greenhouse gas (GHG) emissions. To test this hypothesis we measured GHG fluxes over a four year period, at a drained and a rewetted organic soil under grassland, which were both grazed for the first two years and not grazed for the following two years. Statistical response functions estimated for gross primary production (GPP) and ecosystem respiration (R eco) were used to reconstruct annual CO 2 –C balances using site-specific models driven by soil temperature, solar radiation, soil water table (WT) and leaf area index (LAI). Annually, soil CO 2 emissions were comparable when grazed, although the rewetted site had a lower net ecosystem carbon balance (NECB) despite displaying higher CH 4 emissions. Both sites have lower CO 2 emissions than typical drained organic soils due to management practices: extensive grazing, no fertilisation and mean annual water tables above À25 cm. When grazing stopped, GPP and R eco increased dramatically driven by vigorous growth of vegetation at both sites. The shallow drained site remained a source of CO 2 and small source of CH 4 while the rewetted site became either neutral or a small sink of CO 2 with decreased CH 4 emissions compared to the grazing period. Nitrous oxide (N 2 O) emissions were negligible at either site. Removing grazing significantly reduced the NECB at both sites but in terms of global warming potential (GWP), the greatest GHG mitigation was in the rewetted site which exerted a cooling effect in the second year after the management shift.

An extensive body of literature demonstrates how higher density leads to more efficient energy use and lower greenhouse gas (GHG) emissions from transport and housing. However, our current understanding seems to be limited on the relationships between the urban form and the GHG emissions, namely how the urban form affects the lifestyles and thus the GHGs on a much wider scale than traditionally assumed. The urban form affects housing types, commuting distances, availability of different goods and services, social contacts and emulation, and the alternatives for pastimes, meaning that lifestyles are actually situated instead of personal projects. As almost all consumption, be it services or products, involves GHG emissions, looking at the emissions from transport and housing may not be sufficient to define whether one form would be more desirable than another. In the paper we analyze the urban form–lifestyle relationships in Finland together with the resulting GHG implications, employing both monetary expenditure and time use data to portray lifestyles in different basic urban forms: metropolitan, urban, semi-urban and rural. The GHG implications are assessed with a life cycle assessment (LCA) method that takes into account the GHG emissions embedded in different goods and services. The paper depicts that, while the direct emissions from transportation and housing energy slightly decrease with higher density, the reductions can be easily overridden by sources of indirect emissions. We also highlight that the indirect emissions actually seem to have strong structural determinants, often undermined in studies concerning sustainable urban forms. Further, we introduce a concept of 'parallel consumption' to explain how the lifestyles especially in more urbanized areas lead to multiplication of consumption outside of the limits of time budget and the living environment. This is also part I of a two-stage study. In part II we will depict how various other contextual and socioeconomic variables are actually also very important to take into account, and how diverse GHG mitigation strategies would be needed for different types of area in different locations towards a low-carbon future.

Alternative fuels have received much attention due to the depletion of world petroleum reserves and increased environmental concerns. Thus processed form of vegetable oil (Biodiesel) offers attractive alternative fuels to compression ignition engines. The present work investigates the engine performance parameters and emissions characteristics for direct injection diesel engine using coconut biodiesel blends without any engine modifications. A total of three fuel samples, such as DF (100% diesel fuel), CB5 (5% coconut biodiesel and 95% DF), and CB15 (15% CB and 85% DF) respectively are used. Engine performance test has been carried out at 100% load, keeping throttle 100% wide open with variable speeds of 1500 to 2400 rpm at an interval of 100 rpm. Whereas, engine emission tests have been carried out at 2200 rpm at 100% and 80% throttle position. As results of investigations, there has been a decrease in torque and brake power, while increase in specific fuel consumption has been observed for biodiesel blended fuels over the entire speed range compared to net diesel fuel. In case of engine exhaust gas emissions, lower HC, CO and, higher CO2 and NOx emissions have been found for biodiesel blended fuels compared to diesel fuel. Moreover, reduction in sound level for both biodiesel blended fuels has been observed when compared to diesel fuel. Therefore, it can be concluded that CB5 and CB15 can be used in diesel engines without any engine modifications and have beneficial effects both in terms of emission reductions and alternative petroleum diesel fuel.

Information and Communication Technologies (ICT) have relevant positive and negative impacts on environmental sustainability on various levels: First-order effects such as increasing electronic waste streams; second-order effects such as improved energy-efficiency of production; third-order effects such as a product-to-service shift in consumption or rebound effects in transport. In the simulation study described in this article, all known relevant effects on all three levels were modeled using a System Dynamics approach in combination with scenario techniques and expert consultations. The prospective study for the European Union with a time-horizon until 2020 revealed great potential for ICT-supported energy management and for a structural change towards a less material-intensive economy, but strong rebound effects in the transport sector whenever ICT applications lead to time or cost savings for transport.

A conference in the conventional form is a very resource-demanding process with considerable environmental impacts. As the host of the 15th International Environmental Informatics Symposium, held in Zurich, October 10-12, 2001, EMPA assessed the effectiveness of different measures to reduce the environmental impact of the conference using the Life Cycle Assessment (LCA) method, including the virtualization of the conference.