Pop Variable: US CO2 Emissions

The Pop Variable

The last variable required is the population. The U.S. Census Bureau provides middle, low and high projections for the U.S. population. It would be interesting to report the emissions for each of the population projections, given a projection for GDP per capita growth and the president's goal for emission intensity reduction. To do this, introduce a dimension, Population, with values Low, Medium and High, and give the summable variables Emissions and Pop this dimension:

base year 2002
scenario year 2012

dimension Population 'Low', 'Medium', 'High'

summvar Emissions{Population}, Pop{Population}
ratio EmissionIntensity, GDPperCap

Emissions.by = 100

EmissionIntensity = incr[-18%]
GDPperCap = growth(<2.0%>)

::   Pop >> GDPperCap * EmissionIntensity -> Emissions

Now population values can be given for each projection:

base year 2002
scenario year 2012

dimension Population 'Low', 'Medium', 'High'

summvar Emissions{Population}, Pop{Population}
ratio EmissionIntensity, GDPperCap

Emissions.by = 100

Pop{Population = 'Low'} = 278.8, 294.1
Pop{Population = 'Medium'} = 280.3, 304.8
Pop{Population = 'High'} = 282.1, 318.9

EmissionIntensity = incr[-18%]
GDPperCap = growth(<2.0%>)

::   Pop >> GDPperCap * EmissionIntensity -> Emissions