The impacts of US’withdrawal from Paris Agreement on carbon emission space and mitigation cost of[1, 2]
other regions and China’s response
Hancheng Dai [1]; Haibin Zhang [2]; Wentao Wang [3][1] College of Environmental Sciences and Engineering, Peking University, Beijing 10087, China; [2] College of International Relationship, Peking University, Beijing 10087, China; [3] Ministry of Science and Technology, Beijing 100038, China

The 23rd AIM International Workshop, National Institute for Environmental Studies, November 27-28, 2017
IntroductionResults

Paris Agreement is helpful to reduce the global greenhouse gases to a certain extent, but not sufficient to achieve
the 2 ℃ target.
I However, President Trump of the U.S. declared to withdraw from the Paris Agreement, which is shocking due tothe important role that the U.S. has played in the international climate negotiation and governance.
I Hence, it is of importance to address such questions as: How will the U.S.’withdrawal affect the implementationof the Paris Agreement, global climate governance and China’s climate policy? How should China react to thenew situation?
I To answer the aforementioned questions, it is necessary to evaluate how the carbon emission space, carbon price,and macroeconomic costs of other parties will be affected by the U.S.’withdrawal.
IU.S. withdrawal will cause
additional macro-economic
losses of achieving carbon
mitigation targets in otherregions.

I

Method and scenario
This study uses a global dynamic CGE model of China’s provincial and the global economy [3], which has been
applied systematically to analyze air pollution reduction [4], human health [5, 6], resource use [7], energy andclimate mitigation policies [8–12] of China at the national [13, 14] and provincial levels [4–6, 8–12].
I The model includes 22 economic sectors in the baseline year of 2002.
I It is constructed using GAMS/MPSGE and is solved in a one-year time step until 2030.
Scenario settingThis study sets up a BaU scenario and four mitigation
scenarios, including (Table 1):
I No withdrawal scenario 27: U.S. follow its
obligation to reduce carbon emissions byby 27% in
2025 from 2005 to 4.11 Gt in 2030. All other countries
also implement NDC commitment.
I Withdrawal scenario 20: U.S. only reduce by 20% in
2025 from 2005 level to 4.68 Gt in 2030. However, othercountries need to make additional efforts to reduce
more emissions to offset the extra emissions from theU.S. based on the population share.
I Withdrawal scenario 13: U.S. only achieves 50% of
the NDC target by reducing the emissions by 13.5
I Withdrawal scenario 00: 2025 emissions of the U.S.
are the same as 2005 level since President Trumprenovates the traditional energy supply sectors byremoving the constraint on coal mining, extraction ofcrude oil and natural gas, and by investing
substantially in infrastructure construction.

In 2030, under the NDC target,
the additional GDP loss will be
US$4.75–19.77 billion (percapita GDP loss of US$3.5–14.8) in China, 3.14–13.22
billion US$ (per capita GDP
loss of US$6.9–29.3) in EU, andUS$0.53–2.31 billion (percapita GDP loss of US$4.4–
Figure 4: The additional GDP change under the NDC and 2 ℃ targets compared with full19.2) in Japan.
implementation of the U.S. obligation scenario (measured in US$, 2002 constant price): (a) 2016–2030 and (b) in 2030.

I

Table 1: Scenario setting of this study.

Under the NDC target, the global cumulative CO₂emissions during the 2010–2030 periods are estimatedto be 984.71 Gt based on UNFCCC and the SSP2 GDP.
I Emission pathway under 2 ℃ 27 scenario refers to theSSP2-26-SPA0 scenario of the IMAGE model in theSSP database of the Fifth Assessment Report [15].
I

Under the 2 ℃ target, theadditional GDP loss will be
US$21.98–71.1 billion (percapita GDP loss of US$16.4–53.1) in China, US$9.35–32.14
billion (per capita GDP loss ofUS$20.7–71.1) in EU, andUS$4.13–13.45 billion (percapita GDP loss of US$34.3–111.7) in Japan.

Figure 5: The additional per capita GDP change under the NDC and 2 ℃ targets compared withfull implementation of the U.S. obligation scenario (measured in US$, 2002 constant price): (a)2016–2030 period and (b) in 2030.

Results
The compressing effects of the U.S. withdrawal are noticeable. It leads to increasing its own emission space but
this is at the cost of other regions.
Under the NDC target, Under
NDC 20, 13, and 00 scenarios
in 2030, it will result in a
substantial decrease in CO₂emissions spaces by 0.8%, 1.6%,
and 3.2% in China, by 1.1%,1.8%, and 3.3% in the EU, andby 0.9%, 1.8%, and 3.7% inJapan, respectively.
I Under the 2 ℃ target, the U.S.
could gain additionalemissions spaces by 48%, 66%,
and 100% compared with thefull implementation of its
obligation in the 2 ℃ 27
scenario. The reduction rate
will be 1.7%, 2.8%, and 5.0% in
China, 1.7%, 2.9%, and 5.5% inFigure 1: The carbon emission trajectories in different scenarios. (a) 2002–2030; (b) Global andthe EU, and 1.5%, 3.0%, andChina’s emissions in 2030.
4.5% in Japan, respectively.
IDiscussion and Conclusion
What did we assess?
I This study explores the impacts of the U.S.’withdrawal from the Paris Agreement on the emission spaces, carbon
prices, and macroeconomic effects in the main countries or regions due to the changed emission pathway of theU.S., given that the global cumulative carbon emissions are constant.
What were found?
I The results show that withdrawal of the U.S. from the Paris Agreement could win the U.S. substantial additional
carbon emissions space and lower carbon prices.
I On the other hand, it will compress the emissions space and push up the macro-economic costs for other regions,and lead to significant change in the implementation of the Paris Agreement and global climate governance.
What shall China react?
I China faces mounting pressure from the international community to assume global climate leadership after theU.S. withdraws,
I We propose that China should reach the high ends of its domestic climate targets under the current NDCs;
I Internationally, China should facilitate the rebuilding of shared climate leadership, replacing the G2 with C5.
Meanwhile, China needs to keep the U.S. engaged in climate cooperation.
Acknowledgements
This study was supported by the 2017 National Natural Science Foundation Project ”The Impacts of U.S.
Withdrawal from Paris Agreement on Global Climate Governance and China’s Response”.
References

U.S. withdrawal will push up
the carbon price of otherregions.
I In 2030, under the NDC target,
the carbon price will rise by
1.1–4.6 US$ t-1 in China, by
3.6–14.9 US$ t-1 in the EU, andby 1.8–7.6 US$ t-1 in Japan.
I Under the 2 ℃ target, thecarbon price will increase by
4.4–14.6 US$ t-1 in China, by
9.7–35.4 US$ t-1 in EU, and by
16.0–53.5 US$ t-1 in Japan.
Figure 2: The carbon price in achieving NDC and 2 ℃ targets (2002 constant price). (a) 2016–2030;(b) in 2030.

Figure 3: Comparing carbon price under the 2 ℃ scenario of this study with IMAGE model [15].

Carbon prices are quite close in2020 but different in 2030
because:I We don’t consider much use oflow-carbon technologies.
I We only accounts for energy
combustion related carbon
emissions. Therefore, carbon
reductions must be achieved
within the energy system.
I Carbon emission constraints
are imposed on each country
in this model while a global
carbon emission constraint is
imposed in the IMAGE model.

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College of Environmental Sciences and Engineering
Peking University