The trilemma of land use 2.2 Figure 2.2-3 40 Annual CO2 Emissions [Gt CO2/year]
Anthropogenic CO2 emissions over time. Source: GCP, 2019
Fossil carbon 30
20
10 Land-use change 0 1960
1970
1980
1990
2000
2010
2018
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effects already mean more frequent, more intense and longer-lasting heat waves worldwide. Many regions are experiencing more frequent and more severe droughts, and the intensity of heavy rainfall events has increased worldwide (IPCC, 2019b:9). Warming has already led to a shift in climate zones and this has had an impact on the distribution areas of plants and animals (IPCC, 2019b:6). The risks – e.g. of water shortages in arid regions, damage from wildfires, degradation of permafrost and unstable food supplies – increase with rising temperatures. The negative economic impacts of unsustainable land management are also expected to be further exacerbated by climate change (IPCC, 2019a: 17). Climate-change mitigation, adaptation to climate change and sustainable land use are therefore closely interwoven. On the one hand, effective climate protection is a decisive prerequisite for sustainable land use because the effects of climate change also increase the pressure on productive land areas (via extreme weather events, forest fires, changes in precipitation patterns, and shifting climate zones leading, for example, to thawing permafrost soils). On the other hand, ambitious climate-change-mitigation scenarios, as described above, often rely on a future large-scale conversion of land areas for the absorption and storage of CO2 from the atmosphere, which, in turn, can endanger sustainable land stewardship. In particular, measures aimed at limiting global warming to 1.5°C must therefore be assessed in the context of a comprehensive sustainability transformation that includes land stewardship. The climate crisis and ways to deal with it also have far-reaching consequences for the biodiversity crisis and the crisis of the food system. The reduction in CO2 emissions from land-use changes (above all deforestation) can have major synergies with the conservation of biodiversity (Section 2.2.3). Measures to remove CO2
from the atmosphere can, on the other hand, interact both positively and negatively with the biodiversity crisis – depending on which of the above-mentioned options is pursued (Section 2.2.3). The creation of such sinks should therefore be looked at in a differentiated way. This is discussed in greater depth in Section 3.1. Possibilities for reducing CH4 and N2O emissions are closely related to agricultural practices and dietary habits and are discussed in Sections 3.3 and 3.4. They must in any case be considered in interaction with the crisis of the food system (Section 2.2.2). In the context of the crises of biodiversity and the food system, the impacts on the climate are an additional stressor which will become more acute as climate change progresses. In mid-latitudes, for example, the climate zones to which the ecosystems are adapted are shifting towards the poles, while in tropical regions new kinds of climate conditions may arise (IPCC, 2019a). However, many land-based options for adaptation to climate change can also simultaneously contribute to combating land degradation or to improving food security. Some responses to climate change have in turn repercussions on climate change. For example, Hannah et al. (2020) show that, as a result of shifting climate zones, new areas could be used to grow various crops such as coffee and wine – a development which would release considerable amounts of CO2. It is therefore important to make the adaptation of land use to climate change itself climate-friendly.
2.2.2 The food-system crisis The global food system, i.e. the interplay of the production, processing, trade and consumption of food, shows
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