Climatic Change
carbon producers to 41.6 (±0.9)% of GMST increase over the total historical period, 27.9
(±0.6)% due to carbon producer-traced emissions between 1980 and 2010 alone.
Emissions traced to the top 20 investor and majority state-owned companies from 1880 to
2010 contributed ∼24.4 (±0.5)% of increase in GMST over the historical period, using best
estimate parameters and full historical forcing (Fig. 2c). From 1880 to 2010, emissions traced
to the two largest investor-owned (Chevron and ExxonMobil) plus the two largest state-owned
(Saudi Aramco and Gazprom) contributed nearly 10% to the historical rise in GMST.
Combustion of products from the top 20 companies from 1980 to 2010 contributed 16.6
(±0.3)% of the historical rise in GMST (Fig. 2d).
3.3 Global sea level
Kopp et al. (2016) report a twentieth century GSL of 12–15 cm. The U.S. Environmental
Protection Agency report data for global average sea level change between 1880 and 2010 of
21.9–23.7 cm (US EPA). The model simulation for best estimate parameters with full historical
forcing yields a GSL over 1880 to 2010 of ∼18 cm (ESM).
Removing the annual emissions traced to 90 major carbon producers from the best estimate
full historical forcing case shows that the combustion of their products from 1880 to 2010 led to a
5.7 (±0.1) cm increase in GSL, 32.1 (±0.4)% of the total anthropogenic contribution to increased
GSL over this period (ESM). Less than half (∼42%) of this is due to major carbon producer-traced
emissions of recent origin. Combustion of their products between 1980 and 2010 led to a 2.38
(±0.03) cm increase, 13.5 (±0.2)% of total GSL increase between 1880 and 2010. Removing all
fossil fuel aerosols decreases the proportional contribution of fossil fuel emissions traced to major
carbon producers to 26.0 (±0.4)% of GSL increase over the total historical period, 10.9 (±0.2)%
due to carbon producer-traced emissions between 1980 and 2010 alone.
The contributions of 1880–2010 emissions traced to the top 20 investor and majority stateowned companies to the increase in GSL (Fig. 2 and ESM) contributed ∼13–16% of increase in
GSL over the historical period. The lower bound used the best estimate parameters and full
historical forcing minus all historical fossil fuel aerosols. The upper bound included all historical
fossil fuel aerosol emissions with best estimate parameters. Combustion of products from the top
20 companies from 1980 to 2010 contributed ∼5–6% of the 1880–2010 historical rise in GSL.
Notably, emissions traced to 14 carbon producers were consistently among the top 20
largest individual company contributors to each global impact across both time periods
(Fig. 2). These include seven investor-owned companies (Chevron, ExxonMobil, BP, Royal
Dutch Shell, ConocoPhillips, Peabody Energy, and Total) and seven majority state-owned
companies (Saudi Aramco, Gazprom, National Iranian Oil Company, Pemex, Petroleos de
Venezuela, Coal India, and Kuwait Petroleum). The rank order of their contributions varies
slightly across impacts and time periods as a function of the relative timing of emissions
(Heede 2014 in the ESM model).
4 Discussion and conclusions
Policymakers, investors, and the public may assign responsibility in various ways for greenhouse gas emissions and subsequent changes in climate and associated impacts. Assigning
responsibility for climate change is a societal judgment, one that can be informed by but not
determined through scientific analysis.