Global health. The current scenario and future perspectives

101 better data, demonstrating human influence on the oceans, cryosphere and biosphere (Eyring et al., 2021). The cumulative effects of these changes result in discouraging figures: 1 million species are severely threatened or face extinction, which accounts for 25% of the studied groups, including vertebrates, invertebrates and terrestrial plants from continental and marine aquatic ecosystems (IPBES, 2019). The loss of wetlands has been three times faster than that of terrestrial forests, to the extent that by 2000, only 13% of the surface area that existed in 1700 remained (IPBES, 2019). In addition to climate change, the causes of loss include the overexploitation of forests and fisheries, invasive species and increased contamination of water, air and soil (Pauly et al., 2005; Farjalla et al., 2018; Koleff et al., 2019). Furthermore, ocean acidification and coral loss are unprecedented processes (IPCC, 2019). In Chile, the reductions in water flows are not only explained by the megadrought affecting the country, particularly the central zone (Garreaud et al., 2017), but also by increased water extraction and anthropogenic alterations in basins, coastal areas and urban environments (Pauchard & Barbosa, 2013; Habit et al., 2019; Aguayo et al., 2021). According to Koleff et al. (2019), the unique characteristics of each region in terms of ecological processes and biodiversity are sometimes overlooked, as their responses vary across different regions of the world, determined by specific evolutionary processes. Figure 1 represents the percentage of loss of terrestrial surface area, which would result in the loss of more than 20% of vertebrate species. This exercise was carried out under four global climate scenarios (RCP 8.5; RCP 6.0; RCP 4.5; RCP 2.6), which estimate climate and land-use changes (conservative models). All these scenarios are based on different socio-economic assumptions according to the author, with or without mitigation for greenhouse gas emissions. The least optimistic scenario is RCP 8.5.