Dynamic projection of anthropogenic emissions in China: methodology and 2015–2050 emission pathways under a range of socio-economic, climate policy, and pollution control scenarios
Authors: Tong Dan , Cheng Jing , Liu Yang , Yu Sha , Yan Liu , Hong Chaopeng , Qin Yu , Zhao Hongyan , Zheng Yixuan , Geng Guannan , Li Meng , Liu Fei , Zhang Yuxuan , Zheng Bo , Clarke Leon , Zhang Qiang 
Published: May 2020

Abstract. Future trends in air pollution and greenhouse gas (GHG)
emissions for China are of great concern to the community. A set of global
scenarios regarding future socio-economic and climate developments, combining
shared socio-economic pathways (SSPs) with climate forcing outcomes as
described by the Representative Concentration Pathways (RCPs), was created
by the Intergovernmental Panel on Climate Change (IPCC). Chinese researchers have also developed various emission scenarios by considering detailed local environmental and climate policies. However, a comprehensive scenario set connecting SSP–RCP scenarios with local policies and representing dynamic emission changes under local policies is still missing. In this work, to fill this gap, we developed a dynamic projection model, the Dynamic Projection model for Emissions in China (DPEC), to explore China's
future anthropogenic emission pathways. The DPEC is designed to
integrate the energy system model, emission inventory model, dynamic
projection model, and parameterized scheme of Chinese policies. The model
contains two main modules, an energy-model-driven activity rate projection
module and a sector-based emission projection module. The activity rate
projection module provides the standardized and unified future energy
scenarios after reorganizing and refining the outputs from the energy system
model. Here we use a new China-focused version of the Global Change
Assessment Model (GCAM-China) to project future energy demand and supply in
China under different SSP–RCP scenarios at the provincial level. The
emission projection module links a bottom-up emission inventory model, the
Multi-resolution Emission Inventory for China (MEIC), to GCAM-China and
accurately tracks the evolution of future combustion and production technologies
and control measures under different environmental policies. We developed
technology-based turnover models for several key emitting sectors (e.g.
coal-fired power plants, key industries, and on-road transportation
sectors), which can simulate the dynamic changes in the unit/vehicle fleet
turnover process by tracking the lifespan of each unit/vehicle on an annual
basis. With the integrated modelling framework, we connected five SSP scenarios
(SSP1–5), five RCP scenarios (RCP8.5, 7.0, 6.0, 4.5, and 2.6), and three
pollution control scenarios (business as usual, BAU; enhanced control
policy, ECP; and best health effect, BHE) to produce six combined emission
scenarios. With those scenarios, we presented a wide range of China's future
emissions to 2050 under different development and policy pathways. We found
that, with a combination of strong low-carbon policy and air pollution
control policy (i.e. SSP1-26-BHE scenario), emissions of major air
pollutants (i.e. SO2, NOx, PM2.5, and non-methane volatile organic compounds – NMVOCs) in China will
be reduced by 34 %–66 % in 2030 and 58 %–87 % in 2050 compared to 2015. End-of-pipe control measures are more effective for reducing air pollutant emissions before 2030, while low-carbon policy will play a more important role
in continuous emission reduction until 2050. In contrast, China's emissions
will remain at a high level until 2050 under a reference scenario without active
actions (i.e. SSP3-70-BAU). Compared to similar scenarios set from the
CMIP6 (Coupled Model Intercomparison Project Phase 6), our estimates of
emission ranges are much lower than the estimates from the harmonized CMIP6 emissions dataset in
2020–2030, but their emission ranges become similar in the year 2050.