There is a large variety of potential options to reduce greenhouse gas emissions. Consumers may shift their preferences to lower carbon intensive alternatives within the same product group, e.g. changing from GHG-intensive meats (ruminants) to less intensive meats (pork and poultry) or select lower-carbon food product categories (vegetarian, vegan or low meat diet). Another option which has gained increasing attention in the past years is the recommendation to consume local and seasonal foods. Some studies highlight the benefits of organic food with regard to low carbon options. There is also significant potential to reduce emissions by options related to the reduction of the overall level of food consumption, as well as of foods with low nutritional value e.g. alcohol, tea, coffee or chocolate. Life-cycle assessment (LCA) studies on this type of options are still rare and contested among scientists. What is unchallenged is the fact that all final consumers need to reduce post-consumer food waste dramatically. Many studies point to the fact that food waste is an important issue and that there is an enormous mitigation potential in addressing this issue. Managing unavoidable food waste properly (e.g. using food waste for animal feed, as fertilizer, compost or to recover energy from anaerobic digestion) is also a potential solution. Additionally, there is a remarkable upswing in community gardening and a trend towards self-growing food. However, the quantification of mitigation benefits of self-grown food or community-based agriculture is still lacking.
The preferred options within the transport sector focus on reducing the number of cars and the associated production emissions. This might be achieved through attempts to increase the intensity of use through shared ownership (car sharing/ pooling/ renting) or a shift to public transport or other low carbon transport modes (bike, walk). Carsharing can enable people to forego buying their own cars and thereby reducing the emissions occurring in the production phase. Selecting a car with low embodied emissions may also be a promising mitigation option for consumers. Lighter and smaller cars with less material input due to improvements in the product design can also prove a good solution in reducing impacts from vehicle production. Currently, vehicles are only labelled with regard to their operational efficiency and do exclude information on embodied emissions arising during all processes of production. Therefore, it is crucial to improve existing information schemes to get a better oversight about the hidden emissions within products.
Buildings / Construction
The most promising potential lies in the use of reclaimed construction materials and/or recycled materials (e.g. higher recycled content blocks, locally recycled aggregates). Except for cement, where there is currently no route to create new cement from old, recycling (in which used material is reduced to liquid form) is significantly less energy intensive than primary production, thus already containing a strong economic motivation. Also smaller homes and a reduced living space per person can be an effective way of reducing greenhouse gas emissions. Switching to GHG extensive construction materials (e.g. sustainable sourced timber or other renewable building materials instead of steel) constitutes effective means in mitigating GHG emissions. The success of proposed actions like co-housing and shared (office) spaces which also intend to reduce the living space per person are not entirely confirmed yet.
In addition to final consumer-oriented options, the most important intermediate hot-spots in the various supply-chains were identified and corresponding options for intermediate actors (e.g. producers) compiled. Inputs for electricity production by coal and gas turned out to be the number one intermediate hot-spot in a large number of supply chains. Increasing the energy efficiency of production processes to reduce electricity demand as well as switching the energy mix (e.g. substituting electricity by direct on-site renewable energy production) are the most important category of intermediate options. Production of resource-intensive materials and products, such as iron and steel or chemicals, was another intermediate hot-spot observed across a large number of supply-chains. Reducing the corresponding material inputs through increased material productivity and re-design or material substitution would therefore be a key intermediate option to decrease the embodied emissions of final products.
These results revealed that a large number of options for reducing emissions embodied in products and services exist across selected consumption areas. There thus exist significant potentials for change and for related reductions of human pressures on the climate. However, the research also often found mitigation options proposed by one study and rejected by another which claimed the opposite effect on embodied greenhouse gas emissions. Reducing one type of greenhouse gas emission may lead to increases in another. Similarly there could be trade-offs with other environmental issues non related to climate change (e.g. water, land-use or resources). Even where absolute reductions can be achieved there could be clashes with other social or economic priorities.Therefore, it was hardly possible to propose a “one-fits-all” high-priority list of mitigation options that would reduce embodied greenhouse gas emissions of final products. Instead, what it needed is a careful consideration and assessment of different side-effects and weighing of interests of the various options.