Climate of Ethiopia - Geography Chapter 5 PDF

Okay, here's the conversion of the document into a structured markdown format, I have included as much detail as possible. ## Chapter Five: Climate of Ethiopia and the Horn ### 5.1 Introduction Ethiopia, located in the Horn of Africa, exhibits a diverse range of altitudinal variations and climatic...

Okay, here's the conversion of the document into a structured markdown format, I have included as much detail as possible. ## Chapter Five: Climate of Ethiopia and the Horn ### 5.1 Introduction Ethiopia, located in the Horn of Africa, exhibits a diverse range of altitudinal variations and climatic conditions due to its proximity to the equator and the Indian Ocean. The climate is influenced by the seasonal migration of the Intertropical Convergence Zone (ITCZ), complex topography, and associated atmospheric circulations. **Key Concepts:** * **Weather:** The immediate state of the atmosphere, including temperature, atmospheric pressure, humidity, wind speed and direction, cloudiness, and precipitation. Weather phenomena occur in the troposphere. * **Climate:** The long-term average of weather conditions, including variations and extremes, over decades or more. **Objectives:** * Differentiate between weather and climate. * Understand the spatiotemporal patterns and distribution of temperature and rainfall in Ethiopia. * Analyze the implications of climate on biophysical and socio-economic aspects. * Understand the causes, consequences, and response mechanisms of climate change. ### 5.2 Elements and Controls of Weather and Climate **Weather Elements:** * Temperature * Atmospheric pressure * Humidity * Wind speed and direction * Cloudiness * Precipitation **Controls of Weather and Climate:** * **Latitude:** Affects solar insolation and temperature. Closer to the equator, there are higher average temperatures and minimal variation in day and night length. * **Inclination of Earth's Axis:** Causes seasonal changes due to the tilt of the Earth's axis ($23\frac{1}{2}^\circ$ from the perpendicular to the ecliptic plane). * **Equinoxes:** Days when the sun is directly over the equator, resulting in equal day and night lengths (March 21 and September 23). * **Solstices:** Points when the sun is farthest from the equator, causing the longest or shortest days (June 21 and December 22). * **Altitude:** Temperature generally decreases with increasing elevation due to the lapse rate. **Lapse Rates:** * **Dry Adiabatic Lapse Rate:** Temperature changes by 10°C per 1000m in unsaturated air. * **Wet Adiabatic Lapse Rate:** Temperature changes by 5°C per 1000m in saturated air. * **Environmental Lapse Rate:** The actual observed change in temperature with altitude, averaging 6.5°C per 1000m. **Key Influences:** * **Latitude:** Determines the amount of solar energy received. Ethiopia's location results in high temperatures and minimal seasonal day-length variation. * **Earth's Axis Tilt:** Creates seasonal variations. The Tropics of Cancer and Capricorn and the Arctic and Antarctic Circles define the extent of solar impact. * **Altitude:** Higher elevations experience lower temperatures due to the lapse rate. **Understanding Lapse Rates:** * **Dry Adiabatic Lapse Rate:** Temperature change in unsaturated air due to expansion and compression without heat exchange. * **Wet Adiabatic Lapse Rate:** Temperature change in saturated air where latent heat from condensation affects the cooling rate. * **Environmental Lapse Rate:** The actual observed temperature change with altitude, influenced by the density and composition of the lower atmosphere. ### 5.3 Spatiotemporal Patterns and Distribution of Temperature and Rainfall in Ethiopia #### 5.3.1 Spatiotemporal Distribution of Temperature **Key Factors Influencing Temperature:** * **Altitude:** The primary determinant of temperature in Ethiopia. Higher altitudes correspond to lower temperatures. * **Latitude:** Close proximity to the equator means high solar insolation throughout the year. * **Humidity and Winds:** These elements also play significant roles in temperature variations. **Temperature Distribution:** * **Highlands vs. Lowlands:** Ethiopia's highlands experience cooler temperatures compared to the tropical lowlands. * **Mean Annual Temperature:** * **Lowlands:** Over 30°C. * **Highlands:** Less than 10°C, particularly in regions like the Bale Mountains. * **Temperature Extremes:** * **Highest Mean Maximum Temperature:** Recorded in the Afar Depression. * **Lowlands of Northwestern and South-eastern Ethiopia:** Mean maximum temperatures exceed 30°C. **Local Temperature Zones (Traditional Terms):** * **Wurch:** >3,200m, < $10^\circ C$ * **Dega:** 2,300-3,300m, 10-15°C * **Woina Dega:** 1,500-2,300m, 15-20°C * **Kola:** 500-1,500m, 20-25°C * **Bereha:** <500m, >25°C **Temporal Temperature Characteristics:** * **Daily vs. Annual Ranges:** * **Daily Range:** Significant variation; can exceed 37°C in lowlands and drop to 10-15°C in highlands. * **Annual Range:** Minimal variation; high consistency due to tropical location. * **Seasonal Variations:** * **March to June:** Highest temperatures. * **November to February:** Lowest temperatures. * **Summer:** Slight temperature increase, particularly in northern regions. * **Southern and Southwestern Highlands:** Lower temperatures during certain seasons due to directness of the sun and rainfall patterns. #### 5.3.2 Spatiotemporal Distribution of Rainfall **Key Factors Influencing Rainfall:** * **Intertropical Convergence Zone (ITCZ):** Central to the rainfall system; its position dictates the seasonal and spatial distribution of rainfall. * **Pressure Cells and Trade Winds:** Influence the movement of moist air masses. **Rainfall Patterns:** * **ITCZ Movement:** * **Northward Shift (July):** Brings equatorial westerlies, leading to the main rainy season. * **Southward Shift (January):** Dominated by Northeast Trade Winds, causing dry conditions except in Afar and Eritrean coastal areas. **Seasonal Rainfall Variability:** * **Summer (June to August):** Most regions receive rain, influenced by the Equatorial Westerlies and Southeast Trade Winds. * **Autumn (September to November):** ITCZ near the equator; Southeast Trade Winds bring rain to southeastern lowlands. * **Winter (December to February):** Dominance of Northeast Trade Winds, minimal rain primarily in Afar and Red Sea coastal areas. * **Spring (March to May):** ITCZ shifts northward; Southeast Trade Winds bring rain to central and southeastern regions. **Rainfall Regions in Ethiopia:** * **Summer Rainfall Region:** Majority of the country, divided into dry and wet zones based on rainfall amounts. * **Wet Zones:** High altitudes with >1,000mm annual rainfall. * **All Year-round Rainfall Region:** Southwestern Ethiopia, influenced by the Guinea Monsoons, with annual rainfall ranging from 1,400 to 2,200mm. * **Autumn and Spring Rainfall Regions:** Southeastern lowlands receive rainfall primarily in these seasons, influenced by Southeast Trade Winds. * Rainfall Amounts: 500 to 1,000mm annually. * **Winter Rainfall Region:** Northeasterly winds bring rain to the Red Sea escarpments and parts of Afar. ### 5.4 Agro-ecological Zones of Ethiopia Ethiopia's diverse altitudes and climatic conditions have led to the formation of distinct agro-ecological zones. These zones are traditionally defined in terms of temperature and include Bereha, Kolla, Weyna Dega, Dega, and Wurch. Each zone has unique characteristics suitable for different types of agriculture and settlement. **The Wurch Zone** * **Altitude:** Higher than 3,200 meters above sea level * **Mean Annual Temperature:** Less than 10°C * **Locations:** Includes mountain systems such as Ras Dashen, Guna, Megezez in North Shoa, Batu, Choke, Abune Yoseph. * **Characteristics:** Cold to moist climate with a significant length of growing periods (211-365 days). Covers 0.98% of Ethiopia's area. **Dega Zone** * **Altitude:** 2,300 - 3,200 meters above sea level * **Mean Annual Temperature:** 11.5°C to 17.5°C * **Rainfall:** 900-1,200 mm annually * **Characteristics:** Cool to humid climate. This zone is densely populated due to reliable rainfall and the absence of vector-borne diseases like malaria. Covers 9.94% of Ethiopia's area. **Weyna Dega Zone** * **Altitude:** 1,500 - 2,300 meters above sea level * **Mean Annual Temperature:** 17.5°C to 20.0°C * **Rainfall:** 800-1,200 mm annually * **Characteristics:** Warm, sub-humid climate. It is the second-largest zone, covering 26.75% of Ethiopia's land. Suitable for a majority of crops with two growing seasons. **Kolla Zone** * **Altitude:** 500-1,500 meters above sea level * **Mean Annual Temperature:** 20.0°C to 27.5°C * **Rainfall:** 200-800 mm annually * **Characteristics:** Warm, semi-arid climate. Rainfall is erratic but can be as high as 1,500 mm in the wet western lowlands of Gambella. Covers 52.94% of Ethiopia's area. It forms the boundary between the hot arid (Bereha) and humid climates (Weyna Dega). **Bereha Zone** * **Altitude:** Below 500 meters * **Mean Annual Temperature:** Above 27.5°C * **Rainfall:** Less than 200 mm annually * **Characteristics:** Hot arid climate typical of desert lowlands. Strong winds, high temperatures, low humidity, and minimal cloud cover are common. Covers 9.39% of Ethiopia's area. Includes regions like the Danakil depression which falls below sea level. **Table of Agro-ecological zones of Ethiopia: Altitude, Rainfall, Growing period, Temperature and Share** | Zone | Altitude (m) | Mean annual Rainfall (mm) | Length of growing periods (days) | Mean Annual Temperature (°C) | Area Share (%) | |-------------|--------------|---------------------------|-------------------------------|------------------------------|---------------| | Wurch | >3,200 | 900-2,200 | 211-365 | Below 10 | 0.98 | | Dega | 2,300-3,200 | 900-1,200 | 121-210 | ≥11.5-17.5 | 9.94 | | Weyna Dega | 1,500-2,300 | 800-1,200 | 91-120 | >17.5-20.0 | 26.75 | | Kolla | 500-1,500 | 200-800 | 46-90 | >20.0-27.5 | 52.94 | | Bereha | <500 | Below 200 | 0-45 | >27.5 | 9.39 | ### 5.5 Climate Change/Global Warming: Causes, Consequences and Response Mechanisms **Definition and Relevance** Climate change refers to significant changes in climate patterns over an extended period, due to both natural variability and human activities. Its relevance today stems from the increased impact of human activities leading to unprecedented changes. #### 5.5.1 Current Trends of Climate in Ethiopia **Temperature Variability:** * Over the last few decades, mean annual temperatures in Ethiopia have risen by 0.2°C to 0.28°C per decade. * A rise of about 1.3°C was observed between 1960 and 2006. * Higher increases were noted in the drier areas of northeast and southeast Ethiopia. **Rainfall Variability:** * Precipitation has remained fairly stable on average but shows significant local variability. * Regions receiving spring and summer rainfall (e.g., southern, southwestern, and southeastern Ethiopia) have seen a decline by 15-20% between 1975 and 2010. * Increasing frequency and severity of extreme events such as floods and droughts. #### 5.5.2 Causes of Climate Change **Natural Causes:** * **Earth Orbital Changes:** Variations in the Earth's tilt affect seasonal strength. * **Energy Budget:** Gradual increase in the Sun's radiation over geological time scales. * **Volcanic Eruptions:** Release of gases and ash can lead to temporary cooling. **Anthropogenic Causes:** * **Industrial Activities:** Significant increase in greenhouse gases ($CO_2$, methane, nitrous oxide) due to industrialization, deforestation, and agriculture. * **Land Use Changes:** Clearing land for agriculture and other activities contributes to greenhouse gas emissions. #### 5.5.3 Consequences of Climate Change **Human Health:** * Increased heat-related mortality and morbidity. * Higher incidence of infectious diseases following extreme weather events. **Water Resources:** * Melting snow and glaciers lead to rising sea levels and altered water cycles. * More frequent and severe droughts and floods. **Agriculture:** * Changes in temperature and rainfall patterns affect crop yields. * Increased physiological stress on livestock and reduced fodder quality. **Ecosystems:** * Altered success and distribution of species. * Potential extinction of species unable to adapt to rapid changes. #### 5.5.4 Climate Response Mechanisms Climate change is a multifaceted issue, and even with the cessation of all greenhouse gas emissions today, its effects will persist due to natural emissions. Thus, response mechanisms to reduce the impact of extreme events are essential. These mechanisms can be categorized into mitigation, adaptation, and resilience. **Traditional and Indigenous Mechanisms** Historically, our forefathers have employed various traditional and indigenous mechanisms to cope with climate variability and extreme weather events. These practices, honed over generations, provide valuable insights into sustainable living and environmental stewardship. **Indigenous Practices:** 1. **Agroforestry:** Integrating trees and shrubs into agricultural lands to enhance soil fertility, provide shade, and reduce soil erosion. 2. **Water Harvesting:** Traditional methods such as terracing and building small check dams to capture and store rainwater for agricultural use during dry periods. 3. **Crop Diversification:** Growing a variety of crops to ensure food security despite changing weather patterns. 4. **Seasonal Migration:** Moving livestock to different grazing areas based on seasonal changes to avoid overgrazing and allow vegetation to recover. These practices reflect a deep understanding of local ecosystems and offer practical strategies that can be integrated with modern approaches to climate resilience. **Mitigation and Its Strategies** Mitigation involves actions taken to reduce and control greenhouse gas emissions to slow the pace of climate change. The goal is to avoid significant human interference with the climate system by either reducing sources of these gases or enhancing the sinks that absorb them. **Mitigation Strategies:** 1. **Practice Energy Efficiency:** Implementing energy-saving measures in industries, homes, and transportation to reduce energy consumption. 2. **Increase Use of Renewable Energy:** Transitioning to solar, wind, hydro, and other renewable energy sources to reduce reliance on fossil fuels. 3. **Efficient Transportation:** Promoting electric public transport, cycling, and shared car services to decrease emissions from vehicles. 4. **Reforestation and Afforestation:** Planting trees and restoring forests to absorb carbon dioxide from the atmosphere. **Adaptation and Its Strategies** Adaptation involves adjusting to actual or expected climate changes to minimize harm and take advantage of potential benefits. This approach aims to reduce vulnerability to adverse effects such as extreme weather events and food insecurity. **Adaptation Strategies:** 1. **Building Flood Defenses:** Constructing levees, sea walls, and flood barriers to protect against rising water levels and storm surges. 2. **Planning for Heatwaves and Higher Temperatures:** Implementing urban planning measures such as green roofs, urban greening, and cooling centers. 3. **Water-Permeable Pavements:** Installing pavements that allow water to pass through, reducing the risk of flooding and improving stormwater management. 4. **Improving Water Storage and Use:** Developing efficient water storage systems and practices to ensure a stable water supply during droughts. 5. **Landscape Restoration and Reforestation:** Restoring degraded landscapes and planting trees to enhance ecosystem resilience and carbon sequestration. 6. **Flexible and Diverse Cultivation:** Encouraging agricultural practices that can adapt to changing weather patterns, such as drought-resistant crops and crop rotation. 7. **Preventive and Precautionary Measures:** Developing evacuation plans, improving healthcare infrastructure, and raising public awareness about climate risks. These adaptation measures aim to build resilience and ensure that communities can withstand and recover from the impacts of climate change.