The trilemma of land use 2.2
alized and globalized and is now dominated by a small number of major players that benefit from ‘economies of scale’ and can maintain and control long supply chains – across several stages of the value chain and in some cases globally. Although it produces sufficient food in terms of quantity, the emphasis is on energy-rich staple foods, while (micro)nutrient-rich foods are neglected. In many regions, fruit, vegetables, and animal products are expensive or unavailable, and highly processed foods continue to drive obesity trends (Swinburn et al., 2019:806). The current market concentration, for example in the case of seeds, also promotes the monotonization of landscapes and the loss of biodiversity (Folke et al., 2019). In addition to population growth, which will lead to a rising demand for food, increasing influences of climate change are expected to affect food production in the future. Ensuring sufficient and healthy food for all people on a sustainable basis is therefore a key challenge for the future and an important constraint on our stewardship of the land (Gerten et al., 2020; Willett et al., 2019). However, agriculture must not be geared solely to producing the greatest possible quantities of food. Rather, the aim should be to produce a wide variety of micronutrient-rich foods in sufficient quantities, and to gear food systems also towards promoting biodiversity instead of focusing on a small number of crops. In relation to the trilemma, the question of the future conversion of near-natural terrestrial ecosystems for food production is of great importance: both climate change and the loss of biodiversity and ecosystem services are directly fuelled by land conversion. But the quality of agricultural practices is also key: livestock densities on grasslands, and tillage and fertilization practices on cropland determine the release of CO2 from soil carbon and of N2O; ruminants and rice cultivation emit methane. Decisions on the use of pesticides or the size and homogeneity of cropland management have a direct impact on biodiversity. There are also additional aspects such as energy use, emissions and the release of toxic substances during the processing and transport of foodstuffs, which are not dealt with in depth in this report. Finally, dietary habits have repercussions on production, processing and transport. Losses, inefficiency and waste also have an impact on the total amount of food to be produced. Alexander et al. (2017) show that – after taking into account losses due to food waste, trophic losses due to animal production, and overconsumption (the excessive amount of food consumed compared to nutritional needs) – only 38% of harvested energy and 28% of harvested protein are used in the form of necessary food consumption in the current food system. A transformation of our food system, including
everything from production systems to dietary habits, is a prerequisite for ensuring reliable and healthy diets for a global population that will grow to more than 9 billion people by 2050, while meeting the challenges of anthropogenic climate change (Section 2.2.1), the loss of biodiversity and ecosystem services (Section 2.2.3), and key aspects of the UN Sustainable Development Goals such as health and poverty reduction (FOLU, 2019; Willett et al., 2019). This will require an integrating view that strategically links the dimensions of the trilemma and aims for synergies.
2.2.3 The biodiversity crisis Biodiversity, i.e. the biological diversity of genes, species and ecosystems (CBD 1992, Art. 2), is distributed very unevenly across the Earth (Figure 2.2-4a). Biodiversity is highest in the tropics and around the equator, the so-called biodiversity hotspots (Figure 2.2-4b; Myers et al., 2000; Kleidon and Mooney, 2008). In the mid-latitudes, on the other hand, biodiversity is much lower (Gaston, 2000; Platnick, 2007) but by no means less important. The diversity of terrestrial (i.e. land) ecosystems can be illustrated by their division into 14 biomes, or 846 ecoregions, within each of which specific biological communities have formed based on the prevailing climate (Figure 2.2-4c; Dinerstein et al., 2017; Olson et al., 2001). Aquatic ecosystems are divided into marine (saltwater) and limnic (freshwater) ecosystems, the latter being found as inland waters integrated into terrestrial ecosystems, e.g. lakes and rivers. Currently, about 1.5 million species have been described (Costello et al., 2013). Estimates of the total number of species worldwide are only approximate. Based on taxonomic assessments, these range from 3 to 100 million (May, 2010); systematic calculations suggest around 8.7 million (Mora et al., 2011) or around 5 ± 3 million species (Costello et al., 2013). At around 82.5%, plants account for the biggest proportion of global biomass. Animals account for only about 0.4%, divided into about 29% fish, 46% marine and 24% terrestrial animals. Of the total animal biomass, about 42% are arthropods (e.g. insects), 4% are farm animals, 2.5% are humans, and only 0.3% are wild mammals (Bar-On et al., 2018; Figure 2.2-5).
The ecosystem services Biodiversity has an immense value for humans and their well-being, and this is based mainly on ecosystem services (Costanza et al., 2017). These are services provided to humans by ecosystems that are themselves
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