Climate Change Impact on Extreme Temperatures and Heat Waves in Armenia

Armenia is located in close neighbourhood to the Mediterranean region and Middle East, which have been identified as climate change 'hot spots' and water-stressed regions. The continental climate and mountain topography of the country further increase the vulnerability to climate change. The trends in nine extreme temperature and five heat wave indices have been analysed over the period 1979-2023 using daily maximum and minimum temperature observations from 40 meteorological stations across Armenia. The results show that climate change induced a significant increase in the frequency and intensity of warm extreme temperature indices and heat waves in recent decades. The most prominent and statistically significant warming trends have been found for the summer season. Extreme temperature indices and heat waves that are based on daily maximum temperatures have shown stronger warming trends at most of the stations, especially in the summer season. These asymmetric warming trends of daytime temperatures have enlarged the daily temperature range. The asymmetric warming was partly attributed to an increase in sunshine duration and a decrease in precipitation and wet days observed in the summer season. The urban heat island (UHI) significantly impacted the frequency and severity of heat waves over Yerevan (the capital city). In contrast to the background climate change effect over the entire country, the asymmetric warming trends of nighttime temperatures were observed over Yerevan due to the UHI effect. The nighttime temperatures reached 25 degrees C-28 degrees C during the heat waves, while the maximum duration of heat wave events reached 10-12 days in recent decades.