In order to call on all parties to actively respond to climate change, implement the national carbon peaking and carbon neutral strategy, fulfill the obligations of the Paris Agreement, and promote the popularization of climate change knowledge, this chapter introduces the scientific and legal basis of climate change, mainly including the scientific connotation of climate change, the main hazards, causes, mitigation and adaptation countermeasures, and the scientific basis of the Convention, the Kyoto Protocol, the Paris Agreement, and other international This chapter introduces the scientific and legal bases of climate change, including the scientific connotation, main hazards, causes, mitigation and adaptation measures, and the main international legal bases of the international climate change process, such as the Convention, the Kyoto Protocol and the Paris Agreement.