Emissions Scenarios - IPCC

592 Glossary of Terms
Fuel Switching
Policy designed to reduce COj emissions by requiring electric
utilities or consumers to switch from high-carbon to lowcarbon
fuels (e.g. from coal to gas).
GHGs
See "Greenhouse Gases".
GHG Reduction Potential
Possible reductions in emissions of greenhouse gasses
(quantified in terms of absolute reductions or in percentages
of baseline emissions) that could be achieved through the use
of technologies and measures.
Global Warming
The hypothesis that the earth's temperature is being
increased, in part, because of emissions of GHGs associated
with human activities, such as buming fossil fuels, biomass
buming, cement manufacture, cow and sheep rearing,
deforestation, and other land-use changes.
Global Warming Potential
A measurement technique to define the relative contribution
of each GHG to atmospheric warming. A GWP can only be
calculated for specified time horizons (e.g. 20 to 500 years)
and for given GHG concentration levels (e.g. current). Both
direct and indirect effects are considered. (Indirect effects
include changes in atmospheric chemistry such as ozone
formation and changes in stratospheric water vapor.) COj has
been assigned a GWP of 1, against which all other GHGs are
compared. For example, methane (CH^) has a GWP that is
currently estimated to be about 21 times greater than that of
over a 100 year time horizon, and thus CH^ has a GWP
of 21. (Note that in the economic literature GWP usually
denotes gross world product, referrred to as global GDP in
this report.)
Greenhouse Effect
The trapping of heat by an envelope of naturally occurring
heat-retaining gases (water vapour, CO2, nitrous oxide (NjO),
CH4, and ozone) that keeps the earth about 30°C (60°F)
warmer than if these gases did not exist.
Greenhouse Gases
Gases in the earth's atmosphere that absorb and re-emit
infrared radiation. These gases occur through both natural and
human-influenced processes. The major GHG is water
vapour. Other GHGs include COj, N2O, CH^, ozone, and
CFCs.
Gridding
The provision of emission or socio-economic activity data in
spatially highly explicit form.
GWP
See "Global Warming Potential".
HFCs
See "Hydrofluorocarbons".
Harmonization
A procedure to ease comparabifity of model results by
adopting common (exogenous) input assumptions. Through
harmonization, differences in emissions outcomes resulting
from differences in model input assumptions (e.g. exogenous
population growth) can be separated from differences that
arise from different intemal model parametrizations (e.g. of
the dynamics of technological change). The scenarios
reported here can be classified into three categories: "fully
harmonized" scenarios share population, GDP, and final
energy use assumptions at the level of the four SRES regions
(and hence also at the global level) between 1990 and 2100
within prespecified bounds. "Globally harmonized" scenarios
share global population and GDP assumptions at the global
level for the 1990 to 2100 period within prespecified bounds
(deviations in one 10-year interval are not considered). "Other
scenarios" have adopted altemative assumptions for
population and GDP than the ones suggested for scenario
harmonization.
Hydrofluorocarbons
HFCs are among the six GHGs to be curbed under the Kyoto
Protocol. They are produced commercially as a substitute for
CFCs. HFCs are used largely in refrigeration and semiconductor
manufacturing. Their GWPs range from 1300 to
11,700 times that of CO2 (over a 100 year time horizon),
depending on the HFC.
Illustrative Scenario
A scenario that is illustrative for each of the six scenario
groups reflected in the Summary for Poticymakers of this
report. They include four revised "scenario markers" for the
scenario groups AIB, A2, Bl and B2, and two additional
scenarios for the AlFI and AIT groups. All scenario groups
are equally sound. See also "(Scenario) Groups" and
"(Scenario) Markers".
Intergovernmental Organization (IGO)
Organizations constituted of govemments. Examples include
the World Bank, the OECD, and the Intemational Civil
Aviation Organization. The UNFCCC allows accreditation of
these IGOs to attend the negotiating sessions.
International Energy Agency (lEA)
Paris-based organization formed in 1973 by the major oUconsuming
nations to manage future oil supply shortfalls.
International Institute for Applied Systems Analysis
(IIASA)
Non-govemmental, intemational, interdisciplinary research
institute located in Laxenburg, Austria. IIASA is supported by
the Academy of Sciences and similar leamed societies from
15 countties. Its research focuses on the human dimensions of
global change.