The "8.5" at the end of SSP5-8.5 refers to a radiative feedback of
8.5(W)/(m^(2))
by 2100 along that scenario a climate sensitivity of 8.5 degrees per doubling of atmospheric CO 2 a global warming level of 8.5 degrees by 2100 a radiative forcing of
8.5(W)/(m^(2))
by 2100 along that scenario