由於氣候變遷對全球帶來不可回復的危害，並成為影響國家安全的重要因素之一，聯合國自1988年起成立「政府間氣候變遷專門委員會」並啟動氣候治理談判，陸續於1992年及1997年通過《聯合國氣候變遷綱要公約》與《京都議定書》兩項協議，是現今全球應對此議題主要的兩項機制，透過每年召開締約方會議的方式進行協商，促進各締約方達成共識，提升全球節能減排的執行成效。 美國與中國的溫室氣體排放量在全球排名前二名，是已開發國家與開發中國家中具影響力的大國，故對氣候治理的立場與政策，成為影響全球節能減排成效的關鍵。然而由於氣候變遷議題涉及政治、經濟及安全利益，因此兩國對聯合國氣候治理機制所規範的「共同但有區別的責任原則」與減排份額規範的遵守，有各自的利益考量，在應對氣候變遷議題上，有衝突與摩擦，也有合作與實踐。 在聯合國所主導的氣候變遷治理機制中，美國與中國呈現競爭關係，但若跳脫此一機制，兩國反而能運用雙邊的交流協商，例如高層會談、簽署協議及戰略與經濟對話等平臺，進行雙邊合作達到自主的節能減排目標。從多邊的聯合國氣候談判機制與雙邊的交流分析，未來美中在應對氣候變遷議題上，仍將是既競爭又合作的關係。如果美國與中國能將現有積極進行雙邊合作立場推進到多邊的國際談判，減少已開發國家與開發中國家對氣候治理立場的分歧，那麼將能在國際氣候談判機制中發揮領導作用，促進新氣候協議的達成，對全球應對氣候變遷有極大的助益。 / Global climate change which has caused irreversible harm and become one of the important factors that affect international security, the United Nations set up Intergovernmental Panel on Climate Change （IPCC） in 1988 has held talks since then. After that United Nations Framework Convention on Climate Change（UNFCCC）and Kyoto Protocol（KP）were passed in 1992 and 1997 respectively, which are the world’s two main mechanisms to promote and enhance the implementation of effective emission reduction. The United States and China’s greenhouse gas emissions are the top two in the world and represent developed countries and developing countries. Their attitudes and policies of climate governance have become the key to the effective reduction in global greenhouse gas emissions. However, due to climate change issues related to political, economic and security interests, diffefent views on “common but differentiated responsibilities” and “responsibilities for emission reductions” give rise to both conflict and cooperation between the two countries. In the United Nations-led climate change governance mechanisms, the United States holds a competitive relationship with China. But outside the mechanisms, their bilateral consultations, such as high-level talks, agreements and U.S.-China Strategic and Economic Dialogue （S&ED） help them achieve reduction targets. In the future, the U.S.-China relations on the climate change issue will continue to be both competitive and cooperative. If they can modify their stances through climate governance, it will be able to play a leadership role in international climate negotiations and promote the new climate agreement to solve global climate change issues effectvely.