insights into population and urbanization (Jiang and O’Neill, 2015; KC and Lutz, 2017) and economic growth (Crespo Cuaresma, 2015; Dellink et al., 2017; Leimbach et al., 2015).

In Fricko et al. (2016), the full quantification of SSP2 is presented using the quantified drivers and an impact assessment modeling framework which links the economic land use model GLOBIOM with an energy demand model MESSAGE. Embedded in this future pathway for SSP2 are the drivers and assumptions, which include: population growth, per capita income growth, intrinsic technical progress for livestock yields, crop yields, and irrigation application efficiencies.

Using alternative SSPs we tested the impacts of our irrigation investment strategies under several indicators. We chose _SSP1: Sustainability_ and _SSP3: A Rocky Road_ because they represented a plausible envelope of development that would be “better” and “worse” than SSP2. Table 4 provides an overview of the global and regional population and GDP drivers for the alternative SSPs. Population growth and the economic development of the region will have impacts on future food demand, as well as the region’s investments and advancements in agricultural productivity. We use an econometric relationship of the per capita income and historical crop yields to estimate the intrinsic technological improvement in crop and livestock yields.

Table 4. Population, GDP and GDP per capita assumptions by region for SSPs

|Region|Indicator|Unit|||2050|||2100||
|---|---|---|---|---|---|---|---|---|---|
||||**_2010_**|**SSP1**|**SSP2**|**SSP3**|**SSP1**|**SSP2**|**SSP3**|
||Population|(billion people)|0.38|0.55|0.61|0.69|0.48|0.65|1.02|
|MNA|GDP|(trillion USD 2005 MER)|1.86|8.38|7.69|6.69|16.56|18.78|12.38|
||GDP per capita|(1000 USD 2005 MER)|4.88|15.14|12.54|9.66|34.82|28.79|12.09|
||Population|(billion people)|0.86|1.55|1.78|2.07|1.69|2.40|3.59|
|AFR|GDP|(trillion USD 2005 MER)|0.84|8.85|6.36|4.44|52.73|46.61|19.34|
||GDP per capita|(1000 USD 2005 MER)|0.98|5.71|3.58|2.15|31.13|19.42|5.39|
||Population|(billion people)|2.02|2.00|2.09|2.21|1.19|1.47|2.01|
|EAP|GDP|(trillion USD 2005 MER)|6.05|39.69|30.26|22.92|45.33|43.56|25.80|
||GDP per capita|(1000 USD 2005 MER)|2.99|19.83|14.45|10.38|38.08|29.66|12.86|
||Population|(billion people)|0.48|0.47|0.49|0.51|0.33|0.42|0.55|
|ECA|GDP|(trillion USD 2005 MER)|2.83|9.39|8.27|6.80|13.05|14.79|9.90|
||GDP per capita|(1000 USD 2005 MER)|5.92|20.12|16.91|13.40|39.37|35.21|17.99|
||Population|(billion people)|0.58|0.67|0.74|0.85|0.48|0.67|1.08|
|LCR|GDP|(trillion USD 2005 MER)|3.19|12.30|10.35|8.61|22.56|23.98|15.08|
||GDP per capita|(1000 USD 2005 MER)|5.46|18.24|13.96|10.09|46.59|35.79|13.97|
||Population|(billion people)|0.35|0.46|0.45|0.38|0.52|0.51|0.29|
|NAM|GDP|(trillion USD 2005 MER)|14.29|33.69|29.93|24.75|56.42|46.59|23.70|
||GDP per capita|(1000 USD 2005 MER)|41.05|72.79|66.10|65.94|108.02|90.50|80.84|
||Population|(billion people)|0.15|0.16|0.15|0.13|0.12|0.12|0.07|
|ADP|GDP|(trillion USD 2005 MER)|5.55|10.48|8.79|6.82|15.81|13.21|5.54|
||GDP per capita|(1000 USD 2005 MER)|36.21|67.00|58.38|52.86|126.62|106.47|75.85|
||Population|(billion people)|1.60|2.05|2.30|2.63|1.53|2.17|3.55|
|SAR|GDP|(trillion USD 2005 MER)|1.48|14.65|10.90|7.52|36.88|35.23|15.97|
||GDP per capita|(1000 USD 2005 MER)|0.92|7.15|4.74|2.86|24.06|16.23|4.50|
||Population|(billion people)|0.41|0.47|0.46|0.39|0.45|0.45|0.26|
|EC|GDP|(trillion USD 2005 MER)|14.17|28.62|26.11|20.00|51.28|49.31|20.47|
||GDP per capita|(1000 USD 2005 MER)|34.47|60.29|56.72|51.52|113.70|109.27|77.69|

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