20th Century Temperatures of Palestine: Variability, Trend and the Global Warming (1901-2000)

Abstract

Historical temperature data of Palestine in the 20th century have been analysed using time series analysis to detect the warming and cooling phases. Linear regression analysis was used to identify the signs and the magnitude of the temperatures trends. Linear correlation coefficient is used to identify the strength of the relationships of the temperature with time. The warming of the first and last decades is a general feature of the monthly, seasonal and annual temperature. The strongest positive trend of 1.2oC/100 years was found in summer and spring, while autumn and winter were warmed by 0.32oC and 0.95oC/100 years respectively. The annual temperature of the last century (1901- 2000) was warmed by 0.9oC. The strongest warming trend was found in the next half of the last century, particularly from around 1970s/mid1980s onward. Annual temperature was significantly warmed by 1.1oC from 1980 onward. Seasonal warming trend from mid 1980s onward was 1.1oC for both Summer and Autumn, and 0.5oC to 0.7oC for Spring and Winter respectively. T-test was applied to validate the statistical significance of the mean temperature differences between 1901-1950 and 1951-2000. Monthly, seasonal and annual temperatures in 1951-2000 showed positive and statistically significant differences, except for a few months. There was gradual decreasing trend/cooling for February and March from 1970s onward.