ecosystems The full title of Target 15.4 is: "By 2030, ensure the conservation of mountain ecosystems, including their biodiversity, in order to enhance their capacity to provide benefits that are essential for sustainable development." This target has two indicators: Indicator 15.4.1: Coverage by protected areas of important sites for mountain biodiversity Indicator 15.4.2: Mountain Green Cover Index The Mountain Green Cover Index measured the percentage of mountain environments covered by green areas and the capacity of those areas to fulfil their ecosystem roles. As of 2017, 76% of the world's mountain areas were covered by green vegetation, including forests, shrubs, grassland and cropland. The Mountain Green Cover was lowest in Western Asia and Northern Africa (60%) and highest in Oceania (96%). Target 15.5: Protect biodiversity and natural habitats The full title of Target 15.5 is: "Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and, by 2020, protect and prevent the extinction of threatened species." This target has one indicator: Indicator 15.5.1 is the "Red List Index". The Red List Index (RLI) shows trends in overall extinction risk for species and is used by governments to track their progress towards targets for reducing biodiversity loss. If the RLI value is 1.0, it means that species are categorized as 'Least Concern'. They will be expected to go extinct in the near future. If the RLI value is 0, this means that the species have gone extinct. Habitat loss, unsustainable hunting, the introduction of invasive species and other factors have led to the extinction of 322 terrestrial vertebrate since 1500. At the same time, the numbers of most living species have declined. According to a detailed assessment by the International Union for Conservation of Nature (IUCN), 24,307 species are now seriously threatened with extinction. A report in 2020 stated that globally, the species extinction risk has worsened by about 10 per cent over the past three decades. The Red List Index is declining, from 0.82 in 1990 to 0.75 in 2015 to 0.73 in 2020. A report in 2018 stated that "biodiversity must be mainstreamed across these sectors and spatial planning integrated accordingly." It also tackles the importance of taking care of land degradation and restoring them where possible. An important goal in 2021 is for the world to agree on a new biodiversity framework at the 15th meeting of the Conference of Parties