An interpretation of multi-model future climate predictions for bioclim variables in Romania

: Climate change is one of the biggest challenges of our century. As many climate models exist for the Romanian territory, each simulating a number of possible future scenarios for the emission of greenhouse gases, it is difficult to summarize the predicted impacts. This paper analyzes the output of a part of the Worldclim dataset, namely the 19 bioclim variables for 11 General Circulation Models, 4 RCP (Representative Concentration Pathway) scenarios and 2 years (2050, 2070) at 5 arc minutes (~10 km). These 19 variables were conceived to be relevant for species physiology across phyla, and are extensively used in current literature for species distribution modelling. In order to make informed choices in the fitting of models (simulations of future niche changes), an interpretation is needed for the future variation of each bioclim variable and each combination of GCM, year and greenhouse gas emission scenario (RCP). While GCM rankings are different for each variable and each year-RCP combination, some general characteristics can be derived for each GCM. For the Romanian territory, the hd model (HadGEM2-AO) can be considered overall as a pessimistic model in relation to temperature and precipitation variables (high temperature increase, high precipitation decrease). The mg GCM (MRI-CGCM3) can be regarded as an optimistic model in relation to predicted temperature increase (less warming), but also in relation to precipitation (higher rainfall). The mi (MIROC-ESM-CHEM) also usually predicts a more humid future in Romania, but with higher temperature increase. The ip GCM (IPSL-CM5A-LR) predicts the highest increase in temperatures during cold months in Romania, as well as drier winters and less temperature variability (monthly and yearly). A moderate model for our country is cc (CCSM4), which can be used as a balanced model (it is optimistic only for cold season temperatures, predicting the lowest increase). Overall, for temperature variables there is a general consensus (increase of temperatures for all combinations of GCM, RCP and year). Regarding precipitations the trends are not very clear. An exception is probably the RCP85 scenario, which causes most GCMs to predict a decrease in precipitation variables, but even for this scenario there are models indicating an increase. Abstract: Schimbările climatice reprezintă una dintre cele mai mare provocări ale secolului. Deoarece pentru teritoriul României există mai multe modele climatice, fiecare simulând un număr