Geoscience Reference
In-Depth Information
to precipitation totals and soil type and, for both arable and grassland, nitrogen
input levels. The selection of production activities within each Land Class is
constrained by:
1. The availability of land of different qualities within each Land Class (including
the possibility of converting one type to another, e.g. ploughing permanent
pasture to create arable land) and the ability to switch resources between
uses;
2. The total volume of production (reflecting consumer demand) and input use
required;
3. Policy constraints that restrict the areas of production activities and input
use, or impose specific land-use patterns in certain areas to conform to
environmental or other objectives (e.g. quotas, limits to input use in designated
areas such as Nitrate Vulnerable Zones).
Within these constraints, land use is determined by the CLUAM according to the
maximum profit that can be earned from all the possible activities on all the
parcels of land. Both the outputs and inputs, for all the scenarios, were measured
in terms of mid-1990s (base year) prices in order to allow direct comparison of
results for the future time periods in equivalent value terms.
The CLUAM generates the following outputs, at the Land Class, regional and
national levels:
1. Changes in livestock numbers and crop and grassland areas;
2. Areas of land under different land types and the area falling out of
agriculture;
3. Areas of land transfers (between land cover types and reflecting land
improvement);
4. Change in the use of inputs, including fertilizer and chemical use per hectare
and in aggregate.
The CLUAM was adapted for use with river catchments by the inclusion and
delineation of the Conwy, Kennet, Tamar and Wye catchments within the model
itself. Eight separate model runs have been undertaken. Four of these are
'reference' runs and four are 'scenario' runs. As the object of the modelling
exercise is to capture the effect of climate change on land use, the four reference
runs represent the future without climate change, but including projections of
future social and economic developments derived from the A2 and B2 climate
scenarios described in the Intergovernmental Panel on Climate Change (IPCC)
Special Report on Emissions Scenarios (SRES; IPCC 2000). The four scenario
runs are based on the A2/B2 socio-economic futures, but also include the Hadley
Centre Climate Model (HadCM) climate change forecasts for the same periods.
Comparison of the scenario and reference runs yields the marginal effect of
climate change alone. Provided alongside the results of these eight model runs
are the results of a further run, called REF1990s, which represents broadly the
current position, before recent (Fischler) Common Agricultural Policy reforms,
which were implemented in 2005.
Search WWH ::
Custom Search