Currently,global climate governance has increasingly become a mainstream discourse on the global agenda.As one of the worlds biggest greenhouse gas(GHG)emitter,the U.S.plays a critical part in global climate governance.Although confronting the'climate fragility'in the dimensions of ecological environment,social economy,and national security,the U.S.still takes a relatively negative attitude toward climate governance,and refuses to join the key international climate regimes.The cost of GHG reduction,domestic structure and GHG reduction dilemma...