Regional and sectoral contributions to climate change
Xuanming SU, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Introduction

Results! Countries’ or regional contributions to climate change are important inthe formulation of climate change policy.
! Developed countries emit CO2 or non-CO2 emissions which may dateCHNUSAJPNINDback to pre-industrial and the historical emissions are large; whiledeveloping countries contribute relative fewer emissions in historicalperiod but increase significantly in recent years or visible future.
! The objective of this study is to quantify the contributions to climatechange for each region or country in the world, as well as therelative contribution from each anthropogenic emission, including
CO2 and non-CO2 emissions or sectoral contribution. A regional
contribution table considering historical timescale will be obtained formaking climate change policy.

Method! Normalized marginal method (Li et al., 2016)! For each GHG emission, we performed three simulations:" one ‘normal’ with all emissions included in the simulation (‘all’);" one with country emissions reduced by a fraction ! (‘!!Country’), here!=0.1%;

Figure 2: Regional contributions to climate change of temperature
increase. The ranges in a indicate the 25th and 75th percentiles; and the bar
indicates the 50th percentile.
CHNUSAJPN

IND" and one with all except the country emissions reduced by the same

fraction (‘!!RoG’, for rest of the globe).
! Relative contribution " following the normalized marginal

method: "#="[Tem(all)"!"Tem(!!Country)]/[2"Tem(all)"!"Tem(!!Contry)"!"Tem(!!RoG)].
! The Simple Climate Model for OPTimization (SCM4OPT) is used forclimate change simulation.
! Climate-related uncertainties:a Land-atmosphere CO2 flux

b Ocean-atmosphere CO2 flux

Figure 3: Regional emissions and contribution trends; Green lines are
cumulative CO2 emissions, blue lines show historical industrial CO2 emissions,orange lines are radiative forcing and red lines are temperature increase
contributed by selected countries. The ranges in a indicate the 25th and 75thpercentiles; and middle solid line indicates the 50th percentile.
Table 1: Climate contributions of industrial CO2 by 2012
2c Adjusted radiative forcing

d Temperature increase

22222205
9158 9275.
368
18554.
8891 59%%

Figure 1: CMIP5 historical simulation used in the model calibration. aLand-atmosphere CO2 flux (unit: GtC yr-1), solid red line indicates mean values

Conclusions

and black solid line shows results from Global Carbon Project 2017. b Oceanatmosphere CO2 flux (unit GtC yr-1), solid red line indicates mean values andblack solid line shows results from Global Carbon Project 2017. c Adjusted
radiative forcing (unit: W m-2), estimated based on Forster et al. (2013). Solidred line indicates mean values. d Temperature increase above preindustrial
level (unit: K). Solid red line indicates mean values.

! This study tries to quantify the contributions to climate change foreach region or country in the world, as well as the contribution fromeach anthropogenic emission.
! The output shows that, developed countries emitted more GHGs in

historical period and the contributions to current climate change arelarge; while the contributions from developing countries are relative small,
however, such contributions will become lager in near future since
their emissions increase rapidly nowadays.