Habitat degradation is the result of human-induced processes that result in a decline in biodiversity, ecosystem functions and services, and resilience and can occur in terrestrial, freshwater or marine and coastal ecosystems. Because degradation can take many forms and be measured in different ways, there are varying estimates on the amount of degraded habitat globally. However, estimates suggest that between 20 and 40 per cent of the global land area alone could be considered degraded, affecting the well-being of at least 3.2 billion people
The main direct drivers of land degradation are the expansion of crop and grazing lands into natural areas, unsustainable agricultural and forestry practices, climate change, and, in specific areas, urban expansion, infrastructure development and extractive industry. Habitat loss through transformation and the decline in the suitability of the remaining habitat through degradation are the leading causes of biodiversity loss. Ecosystems affected by land degradation mainly include forests, rangelands and wetlands. Wetlands are particularly degraded, with 87 per cent lost globally in the last 300 years, and 54 per cent since 1900. Marine ecosystems are experiencing high rates of habitat loss and degradation as well, particularly along coastlines, mangrove forests and coral reefs.