Uncertainties in modelling of climate change impact in future: An example of onion thrips (Thrips Tabaci Lindeman) in Slovenia

Uncertainties related to the climate impact studies are reviewed on the case of onion thrips in Slovenia. Paper illustrates cumulative uncertainty introduced by future emission scenarios, general circulation models, downscaling procedures, weather generators and impact (degree-day) models as common tools in climate impact studies. The result of cumulative uncertainty is a wide range of expected warming in Slovenia in the 21st century. An expected increase of air temperature, relative to 1990, is between 1.5 and 7 °C till the end of present century. Due to heterogeneity of the present climate conditions in Slovenia, quite uniform air temperature increase on the entire area will have different impact on the change of cumulative degree-days (DD) and related number of generations of onion thrips per year (Ngen) in different regions. An example of Ljubljana and Bilje shows that larger increase of DD and related Ngen is expected for regions with warmer climate. As a result, more damage will probably be caused in areas that are already strongly exposed to the problem of onion thrips. Harmfulness of the pest in the areas, where it is not a serious threat at present, will also increase. However, we have to be fully aware of a large amount of uncertainty related to studies of climate change impact while interpreting their results.