chapter - Atmospheric and Oceanic Science

of the global climate system to the increase of GHG concentrations. Likewise, high
resolution models nested in the boundary conditions provided by the GCMs have
the potential to provide geographically and physically consistent estimates of
regional climate change.
The limitations of use of GCMs outputs for impact assessments can be summarized
as:
I) The large computing resources needed to undertake GCM simulations and store
their outputs, which restricts the range of experiments capable to be carried out.
II) The coarse spatial resolution compared to the scale of many impact assessments
III) The difficulty to distinguish an anthropogenic signal from the noise of natural
internal model variability
IV) The difference in the climatic response among the different models.
12.4. Development of other scenarios
Independently if in future climate changes will take place, there will be modifications
in the socio-economic and environmental conditions. Therefore in the
preparation of future scenarios is necessary to make projections about the way these
factors will change.
12.4.1. Socio-economic scenarios
Climate scenarios
The most important cause of the rapid changes observed in the atmospheric
composition is the human economic activity, which produces GHG and aerosol
emissions and changes in the land cover and land use. The socio-economic scenarios
developed by the IPCC in its last report and called SRES Scenarios include projections
up to year 2100 and although they are frequently called “emissions scenarios”,
they contain a wide variety of socio- economic assumptions.
The following terminology is used in reference of these scenarios:
• Storyline: It consists of a narrative description of a scenario (or family of scenarios)
with emphasis in the main characteristics and dynamics of the scenario.
• Scenario: projections of a potential future, based on the quantification of a storyline
• Scenario family: one or more scenarios with the same demographic, politicosocietal,
economic and technological storyline.
The IPCC has proposed four scenarios families: The storylines of each of
these families describes a demographic, politico-societal, economical and techno-
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