Evaluation of policies and actions for nature-based solutions in nationally determined contributions

Nature-based solutions (NbS) have been gradually valued by various countries because they have great potential for contributing to the Paris Agreement goals and carbon neutrality and meanwhile render synergies in various dimensions. Currently, the evaluation of NbS policies in the Nationally Determined Contributions (NDCs) is still quite lacking. Based on the NDCs documents of 190 countries and the initial subcategories of related researches, this paper proposes a NbS analysis framework covering targets, pathways, policies, and synergies. Then examining the characteristics of NbS policies and actions of 190 Parties by ecosystems, including forests, farmlands, grasslands, coastal zones & wetlands, urban ecosystems, and other ecosystems with the framework. The results show that: 1) NbS has not yet become the mainstream measure worldwide to combat climate change while developing countries pay more attention to NbS than developed countries; 2) Current NbS targets set by 131 countries(about 69 %) are qualitative and 59 countries(about 31 %) for quantitative. There is no robust and accurate quantitative indicator system for NbS; 3) NbS pathways mentioned by 156 countries (about 82 %) are unevenly distributed in ecosystems and concentrated in forest and farmland ecosystems; 4) Just over a third of the 190 countries (about 35 %) don’t apply any NbS pathways with scientific foundations and only 27 parties (about 14 %) announce strengthening the related research of NbS pathways in supporting policies in the future. The scientific foundations of NbS are undervalued and more NbS pathways with reliable scientific foundations should be implemented; 5) A variety of policies, predominantly planning and law, have been adopted by 130 countries (about 68 %) to ensure NbS actions. Other types of policies still need to be further improved, covering financing, information system &research, and capacity building; 6) Funding needs are unclear and financing mechanisms are imperfect for NbS actions. Only about 1/6 of the countries have suggested estimated funding needs of NbS actions; 7) Only 18 countries (about 9.5 %) have recognized the synergistic benefits of NbS in economic, social, and environmental dimensions, and there are relatively limited methodologies for the assessment of NbS synergies. At last, suggestions are put forward to further promote NbS contributions to tackling climate change.