Sharply reduce pollution in terrestrial ecosystems

How pollution drives biodiversity loss in terrestrial ecosystems

Pollution is one of the five major drivers of terrestrial biodiversity loss. Nearly one-fifth of species at risk of extinction are threatened by pollution, including 6% of terrestrial species at risk of extinction listed on the IUCN Red List of Threatened Species. Beyond the harms to individual organisms and species, pollution also disrupts vital ecosystem functions and the ecosystem services they provide, including nutrient cycling, pollination and natural pest control.

Protecting terrestrial biodiversity requires both limiting the production and use of pollutants and improving pollution remediation measures. Pollutants enter terrestrial ecosystems through multiple pathways, including surface water runoff, soil erosion, groundwater contamination affecting plant roots, and airborne spread. Because many species move across ecosystems, organisms that ingest or absorb contaminants in one ecosystem can carry them into forests, grasslands, peatlands and coastal wetlands, spreading impacts far beyond the original source.
 

The major pollutants threatening forests, grasslands, peatlands and wetlands

Tackling the forms of pollution that most threaten biodiversity in forests, grasslands, peatlands and coastal wetlands — including through soil and water contamination and light pollution — is essential to halting species loss. Some of the most common pollutants harming these ecosystems include heavy metals and metalloids, persistent organic pollutants (including “forever chemicals” and some pesticides), excess nitrogen and phosphorus, plastics and artificial light.

Among the most concerning pollutants are those that do not degrade over time, including heavy metals and persistent organic pollutants such as the “forever chemicals” per- and polyfluoroalkyl substances (PFAS) and polychlorinated biphenyls (PCBs). Instead, they bioaccumulate in organisms and biomagnify in food webs, posing risks to animals, plants and humans for centuries after their initial use. In humans, the accumulation of heavy metals and PFAS chemicals can increase the risk of a range of adverse health effects, including reproductive problems, nervous system harms, certain cancers, cardiovascular disease (metals), and immune system dysregulation (PFAS).

Many pesticides are also persistent organic pollutants. Pesticide exposure is associated with extensive harmful effects to beneficial insects, birds and other organisms that are not the intended target of the pesticide use.

Nutrient pollution from excess nitrogen and phosphorus is another significant threat to biodiversity. One of the most direct harms from excess nutrients is eutrophication, which can lead to contaminated drinking water and shellfish, degraded ecosystem services, and biodiversity losses in inland and coastal wetlands. Soil acidification caused by nitrogen settling onto soils is another concern, threatening species richness in terrestrial ecosystems.

Plastic pollution further disrupts ecosystems, as plastics degrade into microplastics that alter soil chemistry and harm both soil organisms and higher trophic levels. Light pollution also impacts the 30% of vertebrates and over 60% of invertebrates that are nocturnal, interfering with reproduction, migration and foraging.
 

Climate change can worsen pollution risks

Notably, climate change is exacerbating both the introduction of pollutants into ecosystems and their adverse effects. For example, melting glaciers, extreme rainfall and changing soil properties are increasing the amount and toxicity of heavy metals present in the environment. Changing precipitation patterns and rising temperatures are expected to increase nitrogen and phosphorus losses from agricultural soils. Similarly, predicted increases in pest pressure, combined with declining pesticide efficacy, are likely to increase pesticide use and its associated harms to ecosystems.
 

Reducing pollution requires action across land, water, food and ocean systems

Although global monitoring remains incomplete, available data indicates that pollution levels remain high worldwide. Reducing pollution effectively requires approaches tailored to its many forms, sources and cross-ecosystem dynamics. Many solutions to address pollutants in freshwater ecosystems, agricultural systems and oceans also benefit terrestrial ecosystems, and vice versa.

Key actions to reduce pollution across terrestrial ecosystems include scaling up investments in the research and development (R&D) of pollution reduction and remediation technologies and practices; improving treatment of wastewater and stormwater; reducing the overapplication of fertilizers and pesticides; passing regulations as well as improving the enforcement of existing laws; and raising consumer awareness of pollution. More comprehensive, consistent and accurate data is also urgently needed to monitor pollution levels over time and the efficacy of interventions to mitigate them.