Shifting of agro-climatic zones, their drought vulnerability, and precipitation and temperature trends in Pakistan

Agro-climatic classification helps to determine the different features of a region. This climatic classification provides a useful insight for a farmer to grow their crops according to the conditions of their region. This study identifies the shifting of moisture index from average values in different agro-climatic zones of Pakistan. Unpredictable climate remains dominant over long periods. Observational data of precipitation and evapotranspiration were used to determine the agro-climatic zone during the period 1951-2010. This study reveals that almost 87% of Pakistan is in extremely arid to semi-arid zones, a 5% decrease in over the last 30 years (1981-2010). The largest decrease of 8% and increase of 5% were observed in the extremely arid and humid zones, respectively. The semi-arid zone is more vulnerable to drought, while intensity and severity are greater in the extremely arid region. An agro-climatic regional analysis identifies 1952, 1969, 2000, 2001 and 2002 as years when the most severe droughts were observed during the study period. The trends of precipitation and temperature were performed at 95% significance level on a monthly, seasonal and annual basis over the entire agro-climatic zone of Pakistan during 1951-2014. The annual precipitation trends show a significant increase of 0.828 mm year(-1) in arid regions, whereas the maximum temperature trends shows a significant increase of 0.014 degrees C year(-1) and 0.018 degrees C year(-1) in extremely arid and humid regions, respectively. The trend of minimum temperature shows an increase over the whole region, which may place pressure on the water demands of crops.