2020-10-27_PERMIT FILE - C1981035 ‎(22)‎

• Permit No: C1981035
• IBM Index Class Name: Permit File
• Doc Date: 10/27/2020
• Section_Exhibit Name: KII Appendix 16 Dunn Ranch LBA Technical Resources Report
• Media Type: D
• Archive: No

consistent set of cumulative emissions projections (out to year 2100) of only the components of radiative
forcing that are meant to serve as input for climate and atmospheric chemistry modeling. There are 4
primary pathways that climate scientists have used for assessment in numerous climate models shown in
Figure 2.2-9 and Figure 2.2-10 and described as follows:
• RCP2.6-Very low emissions levels leading to peak in radiative forcing at 3.1 W/mZ by mid-century,
returning to 2.6 W/mZ by 2100, where greenhouse gas emissions (and indirectly emissions of air
pollutants) are reduced substantially over time. This pathway provides for an abrupt and rapid
decline in CO2 emissions starting around 2020, with atmospheric concentrations of GHGs and
subsequent radiative forcing stabilizing between 2040 and 2060. This scenario also provides for
"negative emissions" starting in 2080, and essentially projects more carbon is removed from the
atmosphere than is emitted.The curve suggests that emissions from fossil fuels and other sources
would decline by approximately 3.5 percent per year until 2040, and then continue at a pace of
approximately 10 percent per year until the emissions become negative between 2070 and 2080.
The cumulative emissions of this pathway are approximately 1,715.7 GtCO2e (2018 - 2100). CO2
alone represents 54.2 percent of the total contributing emissions and 81.5 percent of the total
CO2 emissions are attributable to fossil fuel use.
• RCP4.5 -Stabilization scenario where total radiative forcing is stabilized at 4.5 W/mZ before 2100
by employment of a range of technologies and strategies for reducing greenhouse gas emissions.
This pathway forecasts global emissions will increase until about 2040, with actual stabilization
occurring between 2030 and 2050. Starting in 2050 emissions would start to decline at rates
commensurate with the 2.6 pathway until 2080, when emissions stabilize again through the end
of the century. GHG concentrations and forcing would continue to rise through the end of the
century,although the rate of increase diminishes significantly around 2070. Emissions of both CH4
and N2O are flat throughout the century and do not contribute significantly to additional radiative
forcing. The cumulative emissions of this pathway are approximately 3,728.6 GtCO2e (2018 -
2100). CO2 alone represents 67 percent of the total contributing emissions and 98.2 percent of
the total CO2 emissions are attributable to fossil fuel use.
• RCP6.0 -Stabilization without overshoot pathway with radiative forcing of 6 W/mZ after 2100 by
employment of a range of technologies and strategies for reducing greenhouse gas emissions.
Emissions of both CH4 and N2O are more-or-less stable throughout the century and do not
contribute significantly to additional radiative forcing, while emissions of CO2 grow steadily until
2080 before declining. The cumulative emissions of this pathway are approximately 5,380.2
GtCO2e (2018 - 2100). CO2 alone represents 74.3 percent of the total contributing emissions and
101.1 percent of the total CO2 emissions are attributable to fossil fuel use. Please note,the Land
Use Change(LUC)CO2 emissions in this scenario are negative at about the midcentury mark,which
produces data showing fossil fuel emissions that are greater than the total emissions (which
include the negative LUC values).
• RCP8.5 -Increasing emissions over time leading to very high greenhouse gas concentration levels
and radiative forcing of 8.5 W/mZ in 2100. This pathway assumes emissions trajectories follow a
historical growth curve and is representative of the high range of non-climate policy scenarios, or
a worst-case scenario that assumes unabated emissions. The cumulative emissions of this
Dunn Ranch Area LBA and Mining Plan Modification 38
Technical Resources Report