What are the implications of declining biodiversity for ecosystems and human societies?

Declining biodiversity is more than the loss of individual species. It can weaken the relationships that keep ecosystems functioning: plants depend on pollinators, predators help regulate prey, and wetlands and forests filter water and store carbon. When those relationships are disrupted, the effects can spread well beyond the species that disappear.

A less diverse ecosystem may also be less able to recover from drought, disease, fires, or other shocks. Losing several species that perform similar roles can leave an ecosystem with fewer ways to keep processes going when conditions change. This can reduce ecosystem resilience, though the impact depends on which species are lost and how quickly the change happens.

People rely on healthy ecosystems for food, clean water, medicines, materials, and livelihoods. Fewer pollinators can affect pollination and crop production; damaged forests, soils, and wetlands can threaten clean water and soil. Biodiversity loss can also affect fisheries, tourism, and the cultural practices of Indigenous and local communities who depend closely on particular species and places.

There can be consequences for human health, too. Changes in habitats and wildlife communities may alter exposure to some infections, but the relationship is complex and varies by disease and location. Overall, biodiversity loss can make essential resources and livelihoods less reliable, with the greatest burdens often falling on people who have fewer alternatives.