Observed climate changes in Croatia Climate change scenario

observations, by which the modelled climate “state” of the atmosphere for the 20 th century is
determined, differences between the future model climate and 20 th century climate have been
analysed. Such differences primarily point out to qualitative assessment of climate change. Due
to a number of uncertainties, quantitative climate change assessments should be taken with
caution. However, they are necessary in order to execute concrete adaptation and mitigation
measures to climate change effects. For example, one of key uncertainties in climate change is
the definition of future scenarios given by IPCC (see chapter 2.1.4). This uncertainty is not a
result of our lack of understanding of climate system, but a fact that human activities and their
possible impact on a future climate should be observed through complex and unpredictable
interactions.
2.1.2 Global model, regional model and dynamical downscaling
Dynamical downscaling has been applied to the results of the EH5OM global model,
included in the IPCC Fourth Assessment Report (AR4). EH5OM is a coupled atmospheric and
oceanic model developed at Max Planck Institute for Meteorology, Hamburg, Germany. Details
of EH5OM are given in Roeckner et al. (2003). The EH5OM simulation of the 20 th century
climate was performed for three different realisations, which differ in a definition of initial
conditions. In such a way, sensitivity of climate model to initial conditions is accounted for. For
the A2 scenario there are also three model realisations available, each of them being the
continuation of the current climate.
The IPCC scenarios for some future period (see Nakićenović et al. 2000) define general
assumptions, which climate models should take into consideration after they have been adapted
to a model. The A2 scenario assumes the growth of global population to 15 billion by 2100, a
moderate economic growth, very high energy consumption and variable hydrocarbons (gas, oil,
coal) consumption, as well as moderate to significant arable land usage. These projections are
then adapted to a model as the concentrations of greenhouse gases and ozone. The A2
scenario is also called the strong forcing scenario because it predicts the most unfavourable
conditions that could occur to the environment – it represents the upper limit of anthropogenic
impact to the atmosphere and climate in this century.
For this report, the results of dynamical downscaling by so-called Regional Climate
Model of the third generation (RegCM3), have been used. RegCM was developed by Dickinson
et al. (1989) and Giorgi (1990). The detailed description of the model version used here is given
in Pal et al. (2007). In our experiments the Grell convection scheme (Grell 1993) has been
applied along with the Fritsch-Chappel closure (Fritsch and Chappel, 1980). The model
horizontal resolution is 35 km in the area with 126 X 88 points centred at 46ºN, 7.5ºE and cover
central and eastern Europe and a large part of the Mediterranean. In the vertical, there are 23
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