Climate change in Vilnius at XXI century

The world population is increasing and the majority of these people live in cities. Increasing anthropogenic impact on the Earth changes the atmospheric composition, land surface and ecological balance. Even if population growth in cities and climate change may not be related at first glance, it remains very important to adapt the cities to increasing population and extreme climatic phenomena. Timely preparations and precautions may help save human lives and reduce damage to city infrastructure.

The temperature and precipitation forecasts for Vilnius were made according to A1B greenhouse gas emission scenario and the average of data derived from three climate models (BCM-RCA, ECHAM5-REMO, HadCM3-HadRM).

The expected average annual, minimum and maximum temperature in Vilnius will grow and by the end of the 21st c. will be 3.0–3.2 ºC higher than the average in 1981–2010.

Most notable temperature changes will take place during the cold season, making it very likely that at the average winter temperature at the end of the century will rise above zero (Fig. 1).

Fig. 1 The average seasonal temperature (°C) in Vilnius during different periods in the future.

 

Increasing temperature will change the pattern of extreme heat or cold. At the end of the century extreme cold (with temperatures lower than -25 °C) in Vilnius should cease. The probability of extreme heat (when the maximum temperature is higher than 30 °C for 3 or more days in a row) should increase by 31 %.

At the end of the 21st c. extreme heat in Vilnius city may repeat on average every 2.5 years (during the period of 1981-2010 it used to repeat approximately every 7.5 years). The cases of tropical nights (when the minimum temperature is at least 20 °C) may increase 13 times, resulting in approximately 7 cases every year at the end of the 21st c. Currently tropical nights in Vilnius don't occur every year.

Predicting precipitation changes is much more difficult, but it is very likely that by the end of the 21st c. the average amount of precipitation in Vilnius will increase by 50 mm (Fig. 2). It is expected that the number of days with precipitation should not change, however the intensity of precipitation will increase. The maximum amount of precipitation may increase by 15 %. The increase will be most notable in winter (24 %) and due to increasing average temperature the increasingly larger share of the winter precipitation will consist of sleet and rain.

Fig. 2 Average annual precipitation (mm) in Vilnius during different periods in the future.

 

This forecast reflects one of the possible scenarios for climate change with the changes subject to the future emissions of greenhouse gasses.

The increased possibility of heat waves and tropical nights may result in larger amounts of people with cardiac and respiratory diseases, increased mortality rate, more common disruption of the transport system or more difficult power and water supply due to extreme weather conditions (rain, heat or snow). Frequent winter temperature fluctuations around 0 °C will result in more intensive frost weathering and corrosion. However, climate changes can also offer new opportunities – increasing temperatures will lengthen the summer tourism season and reduce general energy costs in winter.

A more detailed forecast for climate change in Vilnius city according to A1B scenario is available here.