FUTURE PROJECTIONS OF CLIMATE CHANGE AND IMPACT ASSESSMENT IN RAINFED POTOHAR REGION, PAKISTAN USING CMIP5 MODELS

Abstract

Climate change is an emerging issue of 21st century. Agriculture sector in rainfed regions of the world is mostly affected by climate change. The economy of developing country Pakistan is dependent on agriculture. Potohar plateau is rainfed and is an important region of Pakistan whose agriculture is adversely affected by abrupt climate. The objectives of present study were undertaken to find out the projections of temperature and precipitation of 21st century under RCP 4.5 and RCP8.5 and also assessment of farmers’ perception about climate change. Observational data of temperature and precipitation for the period of 1981-2010 were used to plot historical trends. The future data of 14 CMIP5 models were used under RCP4.5 and RCP8.5 for the period of 2021-2100. The study area was divided into two Grids: Grid 1 (Islamabad, Rawalpindi and Jhelum) and Grid 2 (Attock and Chakwal). To find out the change in the temperature and precipitation boxplots and time series were plotted. The future projections were concluded by applying ground truthing. The ground-based survey was evaluated through three statistical test Mann Kendall, correlation and Regression. Models’ results show that under RCP 4.5 temperature will increases in both grids up to 4°C. Under RCP 8.5 it will increase up to 7℃ in both grids. Large temperature variations will occur in grid1. Precipitation will show variation in both regions along with large variations. Under RCP8.5, temperature will more increase in both grids up to 5°C and large temperature variations will occur in grid 1. In both grids, precipitation change will show variation. According to MK and SS tests, the models show significant increase in grid 1 for historical and future periods at 95% confidence level. Moreover. In the historic grid 1, models show the increasing rate of temperature as: IPSL-CM5A-LR (0.05), MIROC-ESM (0.07), MIROC-ESM-CHEM (0.06) and NorESM1-M (0.05). In historic grid 2, the models show rate of increase of temperature as IPSL-CM5A-LR (0.04), GFDL-CM3 (0.03), MIROCESM (0.06), NorESM1-M (0.05). For future their outputs in grid 1 under RCP 4.5 are: IPSLCM5A-LR (0.03), MIROC-ESM (0.02), MIROC-ESM-CHEM (0.03) and NorESM1-M (0.01). In grid 2 their outputs are: IPSL-CM5A-LR (0.02), GFDL-CM3 (0.03) MIROCESM (0.03), and NorESM1-M (0.02). For future their outputs in grid 1 under RCP 8.5 are: IPSL-CM5A-LR (0.08), MIROC-ESM (0.10), MIROC-ESM-CHEM (0.10) and NorESM1- M (0.05). In grid 2 their outputs are: IPSL-CM5A-LR (0.08), GFDL-CM3 (0.10) MIROCv ESM (0.03), and NorESM1-M (0.01). For precipitation, only NorESM1-M shows statistically significant results at 90% confidence level. In historic grid 1 it shows -0.96 rate. For future under RCP 4.5 it gives 0.67 value in grid 1. Under RCP 8.5 in grid 1 it shows 1.21 rate. According to models’ results, noticeable change of temperature and precipitation will occur. According to field survey, noticeable change in climate change variables is present in Potohar region which was confirmed with models’ results. The methodology of the study can be equally applied to the other districts not only in Pakistan but in the other parts off the world for the purpose of future projections and impact assessment.