Climate Change Downscaling Using Stochastic Weather Generator Model in Rift Valley Basins of Ethiopia

Magarsa Ensarmu Fereda,Feyisa Seboka Tura,Kinde Negessa Disasa

doi:10.4236/ajcc.2019.84030

Abstract

Agriculture is the mainstay of Ethiopian economy. Developing country like Ethiopia suffers from climate change, due to their limited economic capability to build irrigation projects to combat the trouble. This study generates climate change in rift valley basins of Ethiopia for three time periods (2020s, 2055s and 2090s) by using two emission scenarios: SRA1B and SRB1 for faster technological and environmental extreme respectively. First, outputs of 15 General Circulation Models (GCMs) under two emission scenarios (SRA1B and SRB1) are statistically downscaled by using LARS-WG software. Probability assessment of bounded range with known distributions is used to deal with the uncertainties of GCMs’ outputs. These GCMs outputs are weighted by considering the ability of each model to simulate historical records. The study result indicates that LARS-WG 5.5 version model is more uncertain to simulate future mean rainfall than generating maximum and minimum mean temperatures. GCMs weight difference for mean rainfall is 0.83 whereas weight difference for minimum and maximum mean temperatures is 0.09 among GCMs models. The study results indicate minimum and maximum temperatures absolute increase in the range of 0.34˚C to 0.58˚C, 0.94˚C to 1.8˚C and 1.42˚C to 3.2˚C and 0.32˚C to 0.56˚C, 0.91˚C to 1.8˚C and 1.34˚C to 3.04˚C respectively in the near-term (2020s), mid-term (2055s) and long-term (2090s) under both emission scenarios. The expected rainfall change percentage during these three time periods considering this GCMs weight difference into account ranges from -2.3% to 7%, 0.375% to 15.83% and 2.625% to 31.1% in the same three time periods. In conclusion, the study results indicate that in coming three time periods, maximum and minimum temperature and rainfall increase is expected in rift valley of basins of Ethiopia.

Highlights

Climate change is considered to be the biggest challenge facing by mankind in the twenty first century
Developing countries like Ethiopia are the ones which could suffer more from the effects of climate change, due to their limited economic capability for constructing irrigation projects to abbreviate climate change impact on crop production which is dominantly based on rainfall
Research conducted on climate change and Ethiopian economy explained that agriculture in Ethiopia is heavily dependent on rain

Summary

Introduction

Climate change is considered to be the biggest challenge facing by mankind in the twenty first century. The change in the climate mean state within a certain time period is referred to as climate variability which can be more detrimental than climate change. Both climate variability and change can lead to severe impacts on different major sectors of the world such as water resources, agriculture, energy and tourism [1]. In the United States and other developed nations, extensive studies on the impacts of climate change on agricultural production have been carried out [2]. Over a 50-year period, the projected reduction in agricultural productivity may lead to 30 percent less average income, compared with the possible outcome in the absence of climate change [5]

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