Bosnia

Climate change Bosnia and Herzegovina

The climate of Bosnia and Herzegovina

General climate characteristics of Bosnia and Herzegovina are greatly influenced by characteristics of Adriatic Sea, local topography-especially the Dinarides Mountains, which are located along the coast and run from NW to SE parallel to the coast - and atmospheric circulation on a macro scale (1).

On the basis of temperature characteristics, the territory of Bosnia and Herzegovina may be divided into three temperature zones: warm, moderate and cold (1):

• The warm zone corresponds to the Adriatic coast and lowland Herzegovina. In lowland Herzegovina, summers are hot and winters are very mild. Mean winter temperatures are above 5°C, whereas summer temperatures reach 40°C. Mean annual temperatures have the value of above 12°C.
• Moderate areas include plain and hilly regions in the central part of the country. Summers are warm and winters are moderately cold. Mean winter temperatures are around 0°C and summer temperatures reach 35°C. Mean annual temperature ranges between 10°C and 12°C, whereas in the area above 500 m, it is below 10°C.
• Cold regions refer to mountainous areas where summers are fair (days moderately warm and nights chilly), while winters are very cold. During at least 3 months of the year, these regions have a mean temperature lower than 0°C.

Annual precipitation amounts range from 800mm in the north along the Sava River to 2000mm in the central and southeastern mountainous regions of the country. Maximum rainfall occurs mostly at the end of autumn or beginning of winter; i.e., in November or December (1).

Air temperature changes until now

The increase in the mean annual temperature in Bosnia and Herzegovina over the last 100 years was around 0.6°C. Trends were different for individual seasons. The biggest trend of increases was seen in the summer and winter (2).

The summer of 2012 was very hot and dry in South-East Europe; it was the hottest and third-driest on record in Serbia (4). For this part of South-East Europe (including parts of Northern Serbia and Southern Hungary, as well as smaller areas in Bosnia-Herzegovina, Croatia and Romania), the change of the likelihood of an extreme summer such as the one of 2012 between the decades of 1960-1970 and 2000-2010 was assessed. This was done by studying decade-long model simulations (general circulation model and an embedded dynamical regional climate model) and observations. From this study it was concluded that the magnitude and frequency of heat waves have increased considerably in South-Europe between the 1960s and the 2000s. In addition, indices combining temperature and precipitation to assess changes in dryness and heat stress risk have been analysed; these results also show an increase in return time, although the results are subject to uncertainties (5).

Precipitation changes until now

The quantity of precipitation shows minimum changes in the previous 100 years of at most +/- 5%. The largest area of Bosnia and Herzegovina shows a negative trend during the spring and summer, while an increase in rainfall is found in the winter half of the year (3). A special related issue is the trend of decrease of snow during the winter periods, which decreases the accumulation of water in mountainous regions. All of these findings point to a serious deficit of water in the spring and summer season that is already being observed.

In the last decade, in the central mountainous zone, there is a trend of increase of rainfall sums at an annual level, whereas in the south-west areas (the area of Mostar) and north-west (area around Prijedor) part of the country there is a trend of decline (excluding final west – area around Bihać). In the north-east part of Bosnia and Herzegovina, particularly the area around Doboj and Sokolac, there is an increase in rainfall (up to 13%) (1).

Air temperature changes in the 21st century

Projections of air temperature change over the Mediterranean for the thirty-year period 2031-2060, compared with 1980-1990 (SRES B2 scenario), indicate (1):

• The largest temperature increases would occur in summer, and in inland areas: Tmin by 4°C and Tmax by 5 °C on average;
• The second largest increase would occur in the fall (2-3°C everywhere);
• Spring temperatures could rise by approximately 2°C;
• Winter and spring temperatures could rise less than 2°C;
• The rise in coastal region temperatures (although less pronounced due to the sea) are expected to be in the 1-2°C range on average, and a bit more than 2°C in summer for Tmax;
• Tmax is expected to rise more than Tmin;
• The increase in the number of summer days, defined as the number of days when Tmax exceeds 25°C, is from 2 to 6 weeks. This translates into about one additional month of summer days on average ;
• The increase in the number of hot days in the Balkans, defined as the number of days with Tmax> 30°C, ranges from 2 weeks along the coast to 5-6 weeks inland, indicating the role the Mediterranean Sea plays in moderating extremely hot weather.

Precipitation changes in the 21st century

Projections of precipitation change over the Mediterranean for the thirty-year period 2031-2060, compared with 1980-1990 (SRES B2 scenario), indicate that all parts of the Mediterranean (including the Balkans) are expected to see a decrease in summertime precipitation and a small decrease or no change in the other seasons (1).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Bosnia and Herzegovina.

1. Vukmir et al. (2009)
2. Majstorovic (2002, 2008), in: Vukmir et al. (2009)
3. Majstorovic et al. (2005), in: Vukmir et al. (2009)
4. Hydrometeorological Service of Serbia (2012b), in: Sippel and Otto (2014)
5. Sippel and Otto (2014)