In 1935, the British botanist Arthur George Tansley redefined the word "ecosystem" as a "complex of organisms and physical factors". In other words, the term "ecosystem" represents the set of living beings (biocenosis) interacting with each other and with their environment (biotope). The biocenosis and the biotope live in symbiosis, they depend on each other. Thus, these numerous ecosystems form a unique place because of their soil and climate characteristics, but also because of the animal and plant species that make them up. Forests, lakes and oceans all represent particular ecosystems. These biomes are beneficial to all living things as they provide, for example, freshwater, fisheries, air and climate regulation (WHO, 2021).
However, anthropogenic activity directly affects more than 70% of the world's land surface (see Figure 1). In 2015, nearly a quarter of the world's ice-free land area was affected by human use, resulting in land degradation and a 23% reduction in agricultural productivity. As a result, it is estimated that erosion of tilled agricultural land would be more than 100 times the rate of soil formation (IPCC, 2020).
Figure 1: Mapping of threatened ecosystems
Source: Swiss Re Institute and multiple data sources
Every day, humans directly and indirectly impact many ecosystems by modifying them (see Figure 2). By altering ecosystems, the initial interactions between the biotope and the biocenosis change. Migratory birds are thus sometimes forced to deviate from their usual migration routes or to modify the time spent in each area. Although some species are adapting to global warming, others are threatened and may become extinct in the long term, thus contributing to the decline of nature. According to the latest IPBES report, one million animal and plant species are threatened with extinction (IPBES, 2019). The black rhino is one example. With only 5,000 individuals, it is one of the most threatened animal species in the world (IUCN, 2021). According to David Attenborough "the only way to save a rhino is to save the environment in which it lives, because there is a mutual dependence between it and millions of other species of animals and plants".
Figure 2: Examples of declines observed in nature at the global level, highlighting the loss of biodiversity caused by direct and indirect drivers of change.
Source: Report of the Global Assessment of Biodiversity and Ecosystem Services - IPBES, 2019
Human activity also promotes the production and high concentration of greenhouse gases such as carbon dioxide (CO2) in the atmosphere. This causes temperatures to rise and leads to global warming (see Figure 3). This is because half of the carbon emitted by human activity over the last 50 years is absorbed by the atmosphere (SDES et al., 2020). Moreover, land and soil managed by humans are no longer carbon sinks but net emitters. This is due in particular to the poor management of the biomass reservoir, promoting massive deforestation and land use change (Bettin et al., 2020).
Figure 3: Greenhouse gases responsible for global warming
Today, the marine environment is the most impacted biome, especially the coral reef. This is mainly due to pollution from agricultural discharges, micro-plastics, overfishing, coastal development, global warming and maritime traffic (Burke et al., 2012). However, it is important to protect this ecosystem as it is one of the richest in biodiversity and provides habitat and food for many species. In 2016, it occupied less than 0.2% of the ocean's surface area but was home to almost 30% of marine biodiversity (Payri et al., 2016). It also forms a natural barrier between the ocean and the coasts, protecting the latter from natural disasters.
The IUCN is a globally recognised organisation that lists various endangered species. In order to protect the various ecosystems, the IUCN has established a red list of endangered species (see Figure 4). It categorises them into three sub-lists: "critical", "endangered" and "vulnerable". This list serves as a basis for all environmental studies that follow the international standards of the World Bank. The aim is thus to initiate the development of categories and criteria for a red list of ecosystems based on the best available information and on the experiences of the IUCN (Rodriguez et al, 2011).
Figure 4: Current global extinction risk in different species groups
Source: Report of the Global Assessment of Biodiversity and Ecosystem Services - IPBES, 2019
Human activities not only increase global warming, but also soil erosion and pollution. They thus contribute to ecosystem imbalances. It is therefore essential to restore biomes, to understand them, and to know how they function for better cohabitation between man and nature. To achieve this, many actors are now trying to preserve ecosystems and slow down their degradation as much as possible. With this in mind, the United Nations (UN) has proclaimed the period 2021-2030 as the "United Nations Decade for Ecosystem Restoration". Beyond environmental issues, the protection of ecosystems is integrated into economic issues Today, 55% of the world's GDP depends on ecosystem services (Swiss Re Group, 2020). To compensate for this, it is necessary to rethink our economic model by taking into account the planet's limited resources. This is also the basis of geomimicry, which consists of imitating nature to minimise our overall impact on the climate.
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