The president’s goal focuses on GDP as a key driver of emissions. We can
represent this visually with an arrow:
However, the connection is not direct. It is modified by the emission intensity. This
can be represented by putting Emission Intensity inside the arrow:
IPAT-S takes this arrow notation and represents it using normal text.
By using a visual notation (the arrow), calculations can be understood at
a glance. By representing the visual language using text characters, IPAT-S scripts
can be sent using e-mail, browsed using any text editor, and
processed by any tool that takes text as input or produces text as output. It is an
accessible format for humans and computers.
In IPAT-S, the relationship between GDP, Emission Intensity and Emissions is written this way:
:: GDP >> EmissionIntensity -> Emissions
Later in the tutorial, GDP and Emissions will be defined as
“summable variables,” because it makes sense to add them up
(GDP is the sum of value added, and total emissions are the sum of emissions from different sources).
EmissionIntensity will be defined as
a “ratio variable,” because it specifies how the ratio of
Emissions to GDP changes over the scenario.
