Figure 1(a) is a graph displaying four lines. It plots population (mlns) on the y or vertical axis, against year from 2000 to 2100. All four lines start from about 6000 and represent RCP2.6, RCP4.5, RCP6 and RCP8.5. RCP2.6, RCP4.5 and RCP6 follow a similar curve where they steadily increase up to 9000 and then very slightly and gradually decline to just under 9000 by 2100. RCP8.5 has a much steeper curve, reching 12000 in 2090 and then very slightly dropping down again by 2100. Figure 1(b) is a graph displaying four lines plotting primary energy consumption (EJ) for the four RCPs shown in figure 1(a). The y or vertical axis plots energy consumption (EJ) against year from 2000 t 2100. RCP2.6, RCP4.5 and RCP6 all start just under 500 EJ and follow a similar curve where they steadily increase up to 750 EJ by 2100, with RCP4.5 being just above and nearly reaching 1000. RCP6 follows the same path but has a much steeper incline, which drops again at 2060 and then slowly increases by 2080. RCP 8.5 starts at 500 EJ and then follows a steep incline up to 1750 EJ by 2100.

2.1 Representative Concentration Pathways