Study of Multi-Model Ensemble High-Resolution Projections of Major Climatic Variables Over the Indus River Basin and Pakistan

Ghulam Hussain Dars,Muhammad Tauseef,Courtenay Strong,Muhammad Raza Najafi,Mehran Sattar

doi:10.22581/muet1982.2101.10

Abstract

Water resources managers and policy-makers need reliable projections of hydro-climatic conditions to develop sound water management policies. Global Climate Models (GCMs) are the primary basis for projecting howthe climate may change over the coming decades. However, GCMs have low spatial resolution and inherentbiases that limit their direct utility for understanding localized climate change impacts. These limitations are particularly pronounced in mountainous areas, where the terrain exhibits variations at scales much finer than the GCM grid spacing. The main goal of this study is to downscale precipitation and mean temperature simulations from an ensemble of 10 GCMs that participated in the Coupled Model Inter-comparison ProjectPhase-5 (CMIP5) under two Representative Concentration Pathways – RCP4.5 and RCP8.5. The simulations were bias corrected using quantile mapping and downscaled to a 30 arc second spatial resolution (approximately 1 km) through using the delta method over the Indus River Basin and Pakistan for 2040-2070. The GCM processing was carried out using the Global Climate Data (GCD) package. The results show that for all seasons and most of the Indus River Basin (IRB) and Pakistan, future precipitation will be highly uncertain except UIB wherein mean annual precipitation is projected to increase by 8% under RCP 4.5 and 14% under RCP 8.5. However, the models are highly confident about increase in the temperature for this region. Relative to the baseline period (1960-1990), the annual mean temperature in the IRB is projected to increase by 2°C under RCP 4.5 and 2.6°C under RCP 8.5 for 2040-2070.

Highlights

The Indus River is often referred to as a “lifeblood” of Pakistan because it provides water for the country’s irrigation system, which is one of the world’s largest irrigation systems.Pakistan is one of the most vulnerable countries to the adverse impacts of climate change
Study of Multi-Model Ensemble High-Resolution Projections of Major Climatic Variables Over the Indus River Basin and Pakistan weather events such as storms, floods, heat waves, etc. and related socio-economic data based on the period 1997 to 2016
According to the Inter-Governmental Panel on Climate Change Assessment Report 5 (IPCC AR5), climate models project that the global temperature is likely to increase from 0.3°C to 1.7°C under the lowest emission scenarios; whereas, it is likely to rise from 2.6°C to 4.8°C for the higher emission scenarios over this region

Summary

Introduction

The Indus River is often referred to as a “lifeblood” of Pakistan because it provides water for the country’s irrigation system, which is one of the world’s largest irrigation systems.Pakistan is one of the most vulnerable countries to the adverse impacts of climate change. The CRI 2018 categorizes the countries accounting the recent impacts of extreme. The country is facing various climaterelated challenges, of which changes in precipitation and temperature are significantly important in the climatic water balance [2, 3]. According to the Inter-Governmental Panel on Climate Change Assessment Report 5 (IPCC AR5), climate models project that the global temperature is likely to increase from 0.3°C to 1.7°C under the lowest emission scenarios; whereas, it is likely to rise from 2.6°C to 4.8°C for the higher emission scenarios over this region. Precipitation in Pakistan has increased significantly over the past century, but future changes in precipitation patterns are not well understood [5]

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Results