Since the Industrial Revolution,climate warming caused by green-house gases has threatened global eco-security and become an important proposition and challenge for global sustainable develop-ment.To address the issue of global warming,countries in the world have made great efforts,including the United Nations Framework Convention on Climate Change signed in 1992 and other landmark legal documents.After nearly three decades of efforts,we witness a gradual progress in terms of goals and actions from carbon dioxide emissions reduction to carbon peaking and carbon neutrality.Nowa-days,carbon neutrality has become a common goal of all countries around the world.As of October 2020,127 countries/regions have put forward their visions of carbon neutrality,and global cities like Copenhagen,Amsterdam,and New York have proposed plans and roadmaps of carbon emissions reduction,which mainly take energy optimization,public transportation,and green buildings as break-throughs to achieve the goal of carbon neutrality.