Outlook on climate change adaptation

Trends and scenarios

Observed climatic changes Current observations show that temperature is clearly rising in the Carpathians. The most warming is observed in summer (between 1.0° and 2.4°C) with an increase of the frequency and intensity of heat waves. The temperature increase shows a gradient from less increase in the East to more increase in the western part of the range. In winter, there is a slight decrease of temperatures in the east and south and a slight increase of only about 0.4°C in the northern and western parts (Werners et al., 2014a). With respect to more extreme events, the number of hot days is increasing, whereas extreme cold temperatures are decreasing in the western part and increasing in the north-eastern part of the region (Spinoni et al., 2015). Changes in rainfall have a high spatial and temporal variability. There is an observed decrease in western and south-eastern parts of the region and an increase in the north and northeast. During the 1961–2010 period, every part of the Carpathian region on average experienced between half and six drought months per year (Antofie et al., 2015). Nevertheless, the sum of precipitation is increasing in summer and winter and decreasing in spring. Projected Scenarios For this report, we analysed temperature and precipitation projections from the 1971-2000 timeline to the near (2021-2050) and distant (2071 -2100) future. The analysis was based on the mean of 12 different regional climate models from the EURO- CORDEX initiative (Jacob et al. 2013). Furthermore,

we took two different Intergovernmental Panel for Climate Change (IPCC) concentration scenarios into account: the scenario Representative Concentration Pathway (RCP) 4.5. is a more optimistic one, assuming a greenhouse gas emission peak in the year 2040 and a decline after; the RCP 8.5. is less optimistic, assuming a continuous increase of greenhouse gas emissions in the 21st century. Which scenario will play out in reality depends on global mitigation efforts. A warming trend is shown in all the scenarios for the entire region (see Figures). Both summer scenarios show an increase of 1.2°C in the North and up to 2°C in the South in the first half of the 21st century. In winter, there is a higher temperature increase in the East than in the West. The highest temperature increase, according to the model calculations, are expected in the Southern mountain ranges. The amount of winter days strongly depends on the elevation. In the second half of the century, the temperature increase is higher. The RCP 4.5 scenario shows a temperature increase of about 2-3 °Cwhereas the RCP 8.5 scenario results show temperature increases in summer and winter of up to 5°C. Precipitation is projected to decrease in summer, particularly in the south and in the mountains by up to -20mm per month. However, the trend is less clear in the short-term projections. Projections of winter precipitation show an increase of up to +20mm, particularly in thenorth.The amount of rainydayswill decrease in the south and increase in the northeast, particularly during summers. The projections show more periods of intense precipitation, which cause

more runoff and less infiltration due to less frequent but more intensive precipitation events. This precipitation trend combined with less water from snowmelt, higher temperatures in summer and, as a result, higher evapotranspiration losses will lead to a higher risk of summer droughts all over the region. Both, the frequency and severity of drought events are expected to increase in the whole Carpathian region (Werners et al., 2014a).

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