Emissions Scenarios - IPCC

Six Modeling Approaches 345
Climate Change
CONSUMPTION
International trade
Economic activity
Energy demand
Industry sector
• Transportation
sector
- automobile
- railway
- airplane
- ship
• Public and other
sectors
ELECTIUCITY
Food demand and supply
Crop
Meat
Pork & chicken
Beef & mutton
Others
~lá.
'^protein
icaloiie
Energy supply
Fossil fuel resources
coal, oil
w o o d
waste
a m I N G
Nuclear power
Biomass
of crop
Renewable energy
hydropower
w i n d
power
geothermal
solar
power
power
,and use change
Cropland
Grassland
Natural forest
Artificial forest
Biomass faim
Urban area
Others
Figure IV-5: Structure of the MARIA model of one region.
evolution of the end-use technologies, represented by the
improvement in end-use energy efficiency. Demand for
primary fuels is determined by the relative costs of
transfoiming them into the secondary fuels. Nuclear, solar, and
hydro are directly consumed by the electricity sector, while
coal and biomass can be transformed into gas and liquids if the
fossil oil and gas become too expensive or run out. Hydrogen
has recently been added to the model, and it, like refined gas
and oil, can be used to generate electricity or as a secondary
fuel for the three final demand sectors.
The energy supply sector provides both renewable (hydro,
solar, and biomass) and non-renewable (coal, oil, gas, and
nuclear) resources. The cost of the fossil resources relates to
the resource base by grade, the cost of production (both
technical and environmental), and to historical production
capacity. The introduction of a graded resource base for fossil
fuel allows the model to test explicitly the importance of fossil
fuel resource constraints as well as to represent unconventional
fuels such as shale oil and methane hydrates. For
unconventional fuels only small amounts are available at low
costs, but large amounts are potentially available at high cost,
or after extensive technology development. Fuel-specific rates
of technical change are available for primary fuel production
and conversion, as are technical change coefficients for each
category of electricity production.
Biomass is supplied by the agriculture sector, and provides the
link between the agriculture, forestry, and land-use module and
the energy module. The former module estimates die allocation
of land to one of five activities (crops, pasture, forestty, modern
biomass, and other) in each region. This allocation reflects the
relative profitability of each of these uses. Profitability is
determined by the prices for crops, livestock, forest products,
and biomass, which reflect regional demand and supply
functions for each product. There are separate technical change
coefficients for crops, livestock/pasture, forestry, and modem
biomass production.
Once the model has reached equilibrium for a period,
emissions of GHGs are computed. For energy, emissions of
CO,, CH4, and N2O reflect fossil fuel use by type of fuel, while
agriculture emissions of these gases reflect land-use change,
the use of fertilizer, and the amount and type of livestock
produced. The high global warming gases (chlorofluorocarbons,
hydrochlorofluorocarbons, hydrofluorocarbons, and
perfluorocarbons) are esfimated only for each category and not
by their individual components. Sulfur emissions are estimated
as a function of fossil fuel use and reflect sulfur controls, the
effectiveness of which is determined by a Kuznets curve that
relates control levels to per capita income.
The emissions estimates are aggregated to a global level and
used as inputs to MAGICC to produce estimates of GHG
concentrations, changes in radiative forcing, and consequent
changes in global mean temperature. The global mean
temperature change is used to drive SCENGEN-derived
changes in climate pattems and to produce estimates of
regional change in temperature, precipitation, and cloud cover.
Finally, the regional changes in temperature are used to
estimate market and non-market based damages. Developingregion
damage functions produce higher damages than those