With the advent of modern environmental policy in the 1960s, stringent regulations were imposed on emissions into air and water. However, the focus was more or less exclusively on stationary pollution sources (i.e., industrial plants), which were relatively easy to monitor and regulate, e.g., through plant-specific emission standards. In addition, during this early era there was a strong emphasis on local environmental impacts, e.g., emissions into nearby river basins causing negative effects on other industries and/or on households in the same community.
Over the years, though, the environmental challenges have increasingly been about targeting various types of diffuse emissions. These stem from scattered sources such as road transport, shipping, aviation, and agriculture. Pollution from diffuse sources takes place over large areas and individually they may not be of concern, but in combination with other diffuse sources they can cause serious overall impacts. The growing importance of global environmental challenges such as climate change in combination with globalization and more international trade in consumer products, adds to this challenge. Managing these issues often requires international negotiations and burden-sharing, which in itself have proved difficult . The difficulties in reaching a stringent-enough global climate agreement illustrate this difficulty.
Diffuse emissions are typically difficult to monitor and therefore also to regulate. For instance, environmental authorities may wish to penalize improper disposal of a waste product since this would help reduce various chemical risks, but such behavior is typically clandestine and difficult to detect. Plastic waste is an apt example; it stems from millions of consumer products, is carried around the world by the currents and winds, and builds up microplastics, particularly in the sea. Many dangerous substances, including chemicals such as solvents and phthalates, are embedded in consumer products, out of which many are imported. Monitoring the potential spread of these substances to humans and the natural environment remains difficult as well. Technological innovation that permits better tracing and tracking of materials should therefore be a priority (see also ).
In order to address these diffuse environmental impacts, society has to find alternative – yet more indirect – ways of monitoring and regulating them. This could translate into attempts to close material cycles and promote a circular economy, i.e., an economy in which the value of products, materials and resources are maintained as long as possible . In practice, this implies an increased focus on reduction, recycling and re-use of virgin materials , material and energy efficiency, as well as sharing of resources (often with the help of various digital platforms such as Uber and Airbnb). In other words, rather than regulating emissions as close to damage done as possible, the authorities may instead support specific activities (e.g., material recycling) and/or technologies (e.g., low-carbon production processes) that can be assumed to correlate with reduced environmental load.
Addressing diffuse emissions in such indirect ways, though, is not straightforward. In several countries, national waste management strategies adhere to the so-called waste hierarchy (see also the EU Waste Framework Directive). This sets priorities for which types of action should be taken, and postulates that waste prevention should be given the highest priority followed by re-use of waste, material recycling, recovery of waste and landfill (in that order). Even though research has shown that this hierarchy is a reasonable rule of thumb from an environmental point of view , it is only a rule of thumb! Deviations from the hierarchy can be motivated in several cases and must therefore be considered (e.g., ).Footnote 3
One important way of encouraging recycling and reuse of products is to support product designs that factor in the reparability and reusability of products. Improved recyclability can also benefit from a modular product structure (e.g., ). However, this also comes with challenges. Often companies manufacture products in such ways that increase the costs of recycling for downstream processors, but for institutional reasons, there may be no means by which the waste recovery facility can provide the manufacturer with any incentives to change the product design [11, 46]. One example is the use of multi-layer plastics for food packaging, which could often be incompatible with mechanical recycling.
While the promotion of material and energy efficiency measures also can be used to address the problem of diffuse environmental impacts, it may be a mixed blessing. Such measures imply that the economy can produce the same amount of goods and services but with less material and energy inputs, but they also lead to a so-called rebound effect . Along with productivity improvements, resources are freed and can be used to increase the production and consumption of other goods. In other words, the efficiency gains may at least partially be cancelled out by increased consumption elsewhere in the economy. For instance, if consumers choose to buy fuel-efficient cars, they are able to travel more or spend the money saved by lower fuel use on other products, which in turn will exploit resources and lead to emissions.
Finally, an increased focus on circular economy solutions will imply that the different sectors of the economy need to become more interdependent. This interdependency is indeed what makes the sought-after efficiency gains possible in the first place. This in turn requires new forms of collaborative models among companies, including novel business models. In some cases, though, this may be difficult to achieve. One example is the use of excess heat from various process industries; it can be employed for supplying energy to residential heating or greenhouses. Such bilateral energy cooperation is already quite common (e.g., in Sweden), but pushing this even further may be hard and/or too costly. Investments in such cooperation are relation-specific , i.e., their returns will depend on the continuation of the relationships. The involved companies may be too heterogeneous in terms of goals, business practices, planning horizons etc., therefore making long-term commitment difficult. Moreover, the excess heat is in an economic sense a byproduct, implying that its supply will be constrained by the production of the main product. Of course, this is valid for many other types of waste products as well, e.g., manure digested to generate biogas, secondary aluminum from scrapped cars.
In brief, the growing importance of addressing diffuse emissions into the natural environment implies that environmental protection has to build on indirect pollution abatement strategies. Pursuing each of these strategies (e.g., promoting recycling and material efficiency), though, imply challenges; they may face important barriers (e.g., for product design, and byproduct use) and could have negative side-effects (e.g., rebound effects). Moreover, a focus on recycling and resource efficiency must not distract from the need to improve the tracing and tracking of hazardous substances and materials as well as provide stronger incentives for product design. Both technological and organizational innovations are needed.