Warming Trends over the Major Urban Centers of Pakistan Due to Climate Change

The urban centers are considered as the prime hub for the human induced climate change consequences due to the higher anthropogenic activities which results in the occurrence of urban heat island and warmer climate in the urban cities. Pakistan is a developing country with high population growth rate, and pulls large population towards its urban centers due to the better life facilities, which is resulting in sprawling urbanization and rapid landuse changes, ultimately affecting the Normal climate patterns of the major urban cities of country. A number of studies have been conducted in the past to investigate the temperature trends over the high elevation zones and lower plains of country. However, this study was conducted to specifically investigate the annual and seasonal temperature trends over the major urban centers of Pakistan including Karachi, Lahore, Islamabad, Peshawar, and Quetta for the period 1990-2020 using the Mann-Kendall test. The Sen's slope estimator method was used to detect the change in magnitude, and the serial correlation in the time series data was removed using the Pre-Whitening method. The results obtained showed a warming trend of annual mean temperature at Karachi, Lahore, Islamabad, and Quetta stations at the rate of about 0.005, 0.005, 0.008, and 0.021 °C/year, respectively at 95% confidence interval, while a substantial decreasing trend was found at the Peshawar station. For the Summer season, Peshawar, Lahore, and Islamabad stations showed a declining trend, while an upward trend was found at the remaining stations. For Winter season, Quetta, Peshawar, Islamabad, and Karachi showed an increasing trend, while a downward trend was found at the Lahore station. For Spring season, Peshawar showed a declining trend, while the remaining stations showed a warming trend. Thus, it was concluded that the landuse changes, rapid urbanization and migrations, and other anthropogenic activities are among the main causes for the warming temperatures over the major urban centers of country.