Page 136 - AJWEP-22-5

Messel, et al.

1. Introduction Tana Basin.
Therefore, the present study aims to address the
Global temperature and precipitation patterns are gap by identifying the relationship between long-term,
shifting due to climate change, significantly affecting multi-variable climatic changes and global emission
the Earth’s climate system. These changes impact patterns and concurrently evaluating the existing
[1]
human communities, agriculture, water resources, policy framework within the specific context of the
and ecosystems. [2],[3] Donat et al. confirmed that Lake Tana Basin. Many studies rely on climatic data
[4]
temperature and precipitation patterns exhibit significant from the past few decades. However, there is a need for
variations globally. longer-term, continuous climate datasets with trends
Recent research highlights that temperature changes in relation to greenhouse gas emissions, along with
are accompanied by rainfall pattern shifts, characterized appropriate climate change adaptation and mitigation
by greater fluctuations in frequency and intensity. policies tailored to the basin. Linking local climate
[5]
These changes affect water availability, agriculture, trends to global drivers and analyzing policy responses
and the frequency of extreme weather events such as within the specific context is essential to capture more
floods and droughts. The factors that contribute to comprehensive trends in climate variability. This
[6]
these variations in rainfall and temperature are well study makes a unique contribution by providing a
established. According to Stocker et al., the main comprehensive, long-term climatic assessment directly
[7]
cause of climate variability and global warming is linked to global emission drivers, coupled with policy
greenhouse gas emissions from human activities, such analysis specific to the basin – addressing a gap in
as fossil fuel combustion and deforestation. holistic regional climate impact and response studies.
Ethiopia, with its reliance on rain-fed agriculture and
climate-sensitive ecosystems, is highly vulnerable to 2. Methods
climate change. [8],[9] Rapid population growth and limited
adaptive capacity exacerbate this vulnerability. Over 2.1. Study area
[10]
recent decades, the country has experienced significant The Lake Tana Basin is the second-largest sub-basin of
changes in rainfall and temperature, affecting food the Blue Nile (Abbay) Basin in Ethiopia and covers an
security, water resources, and agricultural productivity. estimated area of 15114 km . Its geographic coordinates
[2]
[11] Thus, understanding temporal variability and trends range from 11°00’0” N to 12°40’0” N latitude and
in rainfall and temperature is crucial for designing 36°45’0” E to 38°15’0” E longitude (Figure 1). The
effective adaptation and mitigation strategies. [12],[13] basin’s highest elevation is ≈4100 m above mean
The Lake Tana Basin, due to its ecological importance sea level (mamsl), with an average elevation of 2025
and socioeconomic significance, serves as a critical mamsl. The Lake Tana Basin has a unimodal rainfall
case study for assessing climate variability. [14],[15] distribution, with a mean annual rainfall estimated at
[18]
The basin has experienced notable shifts in rainfall 1280 mm. Most rainfall occurs during the summer
[16]
and temperature patterns, impacting agriculture, season, from mid-June to mid-September. The mean
livelihoods, and water resources. [16],[17] Studies indicate annual temperature of the basin is 21°C. [20],[21]
that temperatures are rising while rainfall is decreasing, Summer (Kiremet) is the basin’s main rainy season,
thereby affecting evaporation rates, water levels, spanning from mid-June to mid-September, with the
and rainfall frequency. [13],[18] This variability poses basin’s climate predominantly characterized as tropical
challenges for water management, food security, and highland monsoon. Air temperature in the basin
[22]
agricultural sustainability. [12],[19] Within the Lake Tana exhibits strong diurnal variation but small annual and
Basin, research by Addisu et al. and Ayalew et al. seasonal fluctuations, with a mean annual temperature
[17]
[12]
has revealed warming trends and declining rainfall, of about 20°C. The basin has a unimodal rainfall
[23]
highlighting the need for climate-resilient infrastructure distribution, receiving the majority of rainfall during
and adaptive agricultural strategies. Contrary to this, the summer. Lake Tana has great economic value for
Tesfaw et al. and Weldegerima et al. reported Ethiopia, serving as a vital resource for agriculture,
[8]
[20]
increasing amounts of annual rainfall in the Lake Tana water supply, and hydropower production. The basin
Basin, though the rate of increase was not statistically also presents significant economic potential, particularly
significant during the periods 1981 – 2020 and 1989 – in areas such as Fogera, Dembia, and Gilgel Abay River
2015, respectively. This suggests a discrepancy between mouth floodplains, which are suitable for irrigation, as
the findings of different studies conducted in the Lake well as in hydropower generation through facilities in

Volume 22 Issue 5 (2025) 130 doi: 10.36922/AJWEP025190142