The need to mitigate climate change, and the role that nature can play in doing so, are recognized under multilateral agreements, including the United Nations Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD). However, we are collectively on a path towards failing to meet the UNFCCC’s Paris Agreement commitment to limit warming to well below 2°C, preferably 1.5°C, as well as CBD targets on biodiversity. So far, human activities have been responsible for a global mean temperature rise of nearly 1.1°C relative to 1850– 1900 levels. If we continue on the current course, it is increasingly likely that the 1.5°C limit will be exceeded in the next 20 years (Intergovernmental Panel on Climate Change [IPCC] 2021).
Immediate, far-reaching action to rapidly cut greenhouse gas emissions and remove CO2 from the atmosphere is necessary if the worst consequences of climate change are to be avoided. Transformative changes of a type never before attempted are required (Pörtner et al. 2021). The 2020 Emissions Gap Report showed that countries need to collectively increase their mitigation ambitions “threefold to get on track to a 2°C goal and more than fivefold to get on track to the 1.5°C goal” (United Nations Environment Programme [UNEP] 2020, p.21). A key action needed to achieve these goals is decarbonizing our economy – radically reducing and eliminating emissions from fossil fuels in energy generation, industry and transport.
All IPCC mitigation pathways consistent with limiting temperature rise to 1.5°C involve, in addition to decarbonization, very significant changes in current land-use trajectories to tackle and reverse these emissions. Although the IPCC does not call them ‘nature-based solutions’, these pathways do include actions of this type, including a halt to deforestation. Achieving the Paris Agreement target of 1.5°C will therefore require a significant contribution from nature-based solutions, as well as the rapid decarbonization of our economies.
While nature-based solutions are a necessary complement to decarbonization, they can only be relied upon when combined with rapid, wide-ranging emissions reductions from energy, industry and transport. Without this dual approach, the total mitigation achieved will be insufficient to avoid climate-related risks (such as changes in temperature and rainfall) that reduce the ability of nature-based solutions to contribute to climate change mitigation (Pörtner et al. 2021).
Despite growing political support for the use of nature-based solutions in climate change mitigation, a number of concerns have been raised. These include: uncertainties about the scale of the contribution, especially given challenges with implementation and financing; doubts about whether the necessary safeguards will be put in place; and worries about the use of offsets by the private sector. This report will assess the current state of knowledge on the size of the contribution that naturebased solutions can make and the types of action they will involve. It will discuss the importance of social and environmental safeguards, how naturebased solutions can be financed and the role of offsets. Most importantly, it will consider the potential of nature-based solutions for mitigation to also contribute to climate adaptation and other pressing challenges.