The entry into force of the Paris Agreement marks the transition of the global climate governance from the negotiation to the compliance. However, that does not mean global climate risk is under control, but rather faces new challenges. In this paper, the three shortcomings of the Paris Agreement are identified, Trump administration's weak climate willingness and their consequencesare are analyzed, and the climate policy possibility of the United States in the future are discussed. It's found that the Paris Agreement has three inherent deficiencies and thus the effectiveness of the Paris Agreement during the implementation process was still dependent on the compliance willingness and compliance capacity of the Parties. Trump administration's climate retreat could have negative impacts on the Parties' compliance willingness and compliance capacity. However, those adverse effects are only short-lived. The status of the United States in the international structure and its established low carbon transition trend will jointly determine Trump administration's withdrawal will not fundamentally shake the Paris Agreement. In the long run, the intention of the United States for global leadership, the domestic dynamics to address climate change, and the moral pressures from outside will inevitably lead the United States to return to the Paris Agreement.

Combining qualitative study and quantitative study, this article analyzes the reasons why U.S. president Trump decided to withdraw from the Paris Agreement, assesses the impact of U.S. withdrawal from the Paris Agreement on the implementation of the Paris Agreement and China, and makes policy suggestions on how China should respond. Undoubtedly, U.S. withdrawal is a big event for global climate governance in the sense that it will exert multi-dimensional impacts on the implementation of the Paris Agreement. U.S. withdrawal seriously undermines the universality of the Paris Agreement, which is perceived as the backbone of global climate regime, aggravates the leadership deficit in global climate governance, sets a bad precedent for global climate cooperation, wins itself more emission right and lower cost of mitigation while squeezing other countries' carbon emission space and raising their cost of mitigation, make it more difficult for developing countries to mitigate and adapt to climate change, may cost the world the window of opportunity in climate mitigation, will compromise the quality of future IPCC reports and ultimately undermine the authority of future negotiations under the Paris Agreement, and finally makes the long term goal much tougher to achieve, even unlikely. In general, the framework of global climate governance will not collapse but will be shaken; the process of global climate governance will not be reversed but will be slowed. U.S. withdrawal poses a lot of challenges to China. One of them is the rising demand and pressure from international community that China should assume global climate leadership alone. In this context, China should achieve the most ambitious targets in the range of its Nationally Determined Contribution (NDC) domestically, and facilitates the reestablishment of shared global climate leadership, which means shifting from G2 to C5 in an active manner internationally. At the same time, China should work hard to pull U.S. back.

Based on the computable general equilibrium (CGE) model and scenario analysis, this article assesses the impacts of the United States' (U.S.) withdrawal from the Paris Agreement on China, European Union (EU) and Japan in terms of carbon emission space and mitigation cost under Nationally Determined Contributions (NDCs) and 2℃ scenarios due to changed emission pathway of U.S. The results show that, under the condition of constant global cumulative carbon emissions and fixed burden sharing scheme among countries, the failure of the U.S. to honor its NDC commitment to different degrees will increase its carbon emission space and decrease its mitigation cost. However, the carbon emission space of other parties, including China, EU and Japan, will be reduced and their mitigation costs will be raised. In 2030, under the 2℃ target, the carbon price will increase by 4.4-14.6 US$/t in China, by 9.7-35.4 US$/t in EU, and by 16.0-53.5 US$/t in Japan. In addition, China, EU and Japan will incur additional GDP loss. Under the 2℃ target in 2030, the GDP loss of China would increase by US$ 22.0 billion-71.1 billion (equivalent to 16.4-53.1 US$ per capita), EU's GDP loss would rise by US$ 9.4 billion-32.1 billion (equivalent to 20.7-71.1 US$ per capita), and Japan's GDP loss will rise by US$ 4.1 billion-13.5 billion (equivalent to 34.3-111.6 US$ per capita).

In the afternoon of June 1, 2017, the United States President Trump officially announced its withdrawal from the Paris Agreement, thus study on the reasons of withdrawal, the follow up impact and coping strategies became the focus of the international community. Based on the self-developed the United States policy evaluation model, this paper systematically evaluates the three gaps of global climate change mitigation, finance and governance after the United States declared its withdrawal from the Paris Agreement, and put forward China's response strategy and suggestion. The study shows that the United States' withdrawal from the Paris Agreement will impact on the existence and implementation of successive climate policies and make the United States' GHG emissions in 2030 reach 5.79 (5.60-5.98) billion tons of CO₂-eq, which is equivalent to a decrease of 12.1% (9.1%-15.0%) at the 2005 level and a rise of 1.64 (1.25-2.01) billion tons of CO₂-eq emission compared to the NDC scenario, and cause additional 8.8% to 13.4% of the global emission reductions deficit. The refusal of the United States to continue to meet its financial support obligations will also worse the situation of current climate finance mechanism. The global climate fund's funding gap will increase by US$ 2 billion, while the gap in long-term climate finance will increase by about US$ 5 billion per year. With at least 40% increase in GCF contributions from Japan and the European Union (EU), while an at least 25.2% increase of EU and its member states' overall financial support, can fulfill the financial deficit caused by the United States. The United States is an important party in the global climate governance, and the impact of the United States' withdrawal has spread to the main agenda of global governance, it is unrealistic to expect China-EU, BASIC plus, and so on to quickly fill the governance deficit caused by the United States at short time and the "low period" of global governance may inevitably last for a while. Although the international community is looking forward to China's leadership in global climate governance, China should have a clear understanding of the cost, benefits and feasibility of playing "leading role" and shall remain be cautious and determine its strategy in addressing climate through long-term plans. At the same time, China should focus more on domestic work, reach a strategic consensus on climate change, and preparing for "leadership" in long-term. China should also actively promote the international cooperation at all levels to find a way to deal with "three deficits" problem.

Since Donald Trump became the president of the United States, whole world is ready for his drop on the Paris Agreement. However, the formal intervention still caused a broadly world reaction. Beside the negative influence on the political credit, international cooperation and potential effect on long term economic of the United States, Trump will not only take advantage of the political reputation building, but get another bargain chance to renegotiate of the Paris Agreement. In general, the United State withdrawal from the Paris Agreement will not change the low-carbon pathway and transformation trend of the global climate regime, but the long-term goal and the international cooperation on climate change will be impacted due to the budget cut on domestic climate change research and the donation cancelation on the multilateral environmental fund from the United States. As long as there is a renegotiation of the Paris Agreement, the common but differentiated principle of responsibility of the United Nations Framework Convention on Climate Change will be challenged again. In future, the climate change governance is still one of the main themes for the sustainable development. Instead of the governments, the multiple roles will improve their acting on climate change governance and local, non-governmental organizations will carry out more technical innovation and pragmatic cooperation. The capacity building on climate change research and awareness should be enhanced as a long-term work.