Ecosystem Change

2. How have ecosystem services and their uses changed?

• 2.1 What are ecosystem services?
• 2.2 What have been the changes in specific ecosystem services?
• 2.3 What are the effects of developing substitutes for ecosystem services?
• 2.4 What is the link between biodiversity and ecosystem services?
• 2.5 What are trade-offs or synergies between ecosystem services?

2.1 What are ecosystem services?

Ecosystem services are the benefits obtained by people from ecosystems. These include:

• provisioning services such as food, water, timber, fiber, and genetic resources;
• regulating services such as the regulation of climate, floods, disease, and water quality;
• cultural services such as recreational, aesthetic, and spiritual benefits;
• supporting services such as soil formation, pollination, and nutrient cycling. Supporting services are not developed further in this question because they are not used directly by humans, even if they are critical to the maintenance of the other types of services.

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2.2 What have been the changes in specific ecosystem services?

Human use of all ecosystem services is growing rapidly. Humans have increased the amount or supply of only a small number of ecosystem services, specifically: crops, livestock, aquaculture, and recently, carbon sequestration. Approximately two thirds of the assessed services have been degraded over the past century, for example, freshwater supply and capture fisheries. More...

2.2.1 Provisioning services are the products obtained from ecosystems, such as food, water, and timber. Their use by humans increased rapidly during the second half of the 20th century and continues to grow. The capacity of ecosystems to provide services in the future is jeopardized when services are used more quickly than they can be renewed. The sustainability of the use of provisioning services differs in different locations, but for several of them overall use is unsustainable. For example:

• The current level of fishing has led to the collapse of many fisheries. One quarter of marine fish stocks is currently overexploited or significantly depleted.
• Overall, a significant part of local freshwater use exceeds the renewable supplies, requiring engineered water transfers or overuse of groundwater.
• In some regions, agricultural practices are not sustainable due to the use of unsustainable sources of water, excessive fertilizer or pesticide use, and soil degradation.

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See also: Table on Trends in human use of provisioning services and their enhancement or degradation

2.2.2 Regulating services are the results of the functioning of ecosystem processes, and include, for example, climate and disease patterns and waste processing. Humans have substantially modified regulating services by modifying the ecosystem providing the service or, in the case of waste processing, by exceeding the capabilities of ecosystems to provide the service.

Changes to ecosystems have led to:

• modified climate regulation through changing levels of carbon dioxide,
• altered patterns of disease due to habitat change, for example because human populations have been brought into closer contact with diseases,
• a significant rise in the number of floods and major wildfires on all continents since the 1940s, and
• reaching limits of the capabilities of ecosystems to eliminate toxins and excess nutrients

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See also: Table on Trends in human use of regulating services and their enhancement or degradation

2.2.3 Cultural Services are the non-material benefits people obtain from ecosystems such as spiritual enrichment, recreation, and aesthetic experiences. Whereas the use of these services has continued to grow, the capability of ecosystems to provide them has been significantly diminished in the past century. Ecosystem change can have a significant impact on cultural identity and social stability. Rapid loss of culturally valued ecosystems and landscapes can contribute to social disruption. More...

See also: Table on Trends in human use of cultural services and their enhancement or degradation

2.3 What are the effects of developing substitutes for ecosystem services?

Figure 2.1 Global fish catch

In the last hundred years, global gains in the supply of food, water, timber, and other provisioning services have often been achieved despite local resource limitations by shifting production and harvest to new less exploited regions. These options are diminishing. Although human demand for ecosystem services continues to grow, the development of substitutes lowers the demand for certain services in particular regions. However, the overall impact of such substitutions may not always be positive. Using fossil fuels instead of fuelwood, for example, reduces indoor air pollution and pressures on forests but increases net greenhouse gas emissions. Substitutes are also often far more expensive to provide than the original ecosystem services. More...

2.4 What is the link between biodiversity and ecosystem services?

Changes in biodiversity affect the ability of ecosystems to supply services and to recover from disturbances. When a species is added or lost at a particular location, the various ecosystem services specifically associated with that species are changed.

Similarly, when a particular habitat is converted for human use, the ecosystem services associated with the species that live there are changed. This often has direct and immediate impacts on people as well as long-term consequences. More...

2.5 What are trade-offs or synergies between ecosystem services?

When humans modify an ecosystem to improve a service it provides, this generally results in changes to other ecosystem services.

Trade-offs: When the improvement of one ecosystem service results in negative effects on other services, the net benefits are often smaller than initially believed. For example, actions to increase food production often involve some of the following: reduced water availability for other uses, degraded water quality, reduced biodiversity, reduced forest cover, loss of forest products, and release of greenhouse gases. Such trade-offs are rarely fully considered in decision-making.

Synergies: Actions to conserve or enhance a particular component of an ecosystem or its services can also produce positive synergies which benefit other services or other stakeholders. For example, urban green spaces fulfill spiritual, aesthetic, educational, and recreational needs, while generating other services such as water purification, wildlife habitat, and carbon sequestration. Positive synergies often occur between regulating, cultural and supporting services and with biodiversity conservation. More...