# Study Notes: Middle and South America ## Resource-Rich Region ### The Amazon Basin - **Geography**: Vast lowlands east of the Andes, dominated by the Amazon River system. - The Amazon River originates in the Andes and slows as it reaches the flat Amazon Plain, depositing silt. - Flooding renews soil fertility with silt and organic material, supporting agriculture. - **Biodiversity**: - The Amazon rainforest is the largest tropical rainforest, home to unparalleled biodiversity. - Contains 20% of Earth's flowing surface water. - Absorbs approximately 28% of global carbon emissions annually (~7.34 billion metric tons). - **Cultural Significance**: - Historically home to 230 ethnic groups; 87 tribes have gone extinct since 1900. - Some of the last undisturbed Native American communities reside here. The Amazon rainforest plays a critical role in regulating the global carbon cycle and mitigating climate change. When the Amazon floods, the deposited silt enriches the soil, making it ideal for crops like cassava and maize. --- ## Climate and Altitudinal Zones ### Altitudinal Zones of the Andes The Andes' elevation creates distinct climate zones, each supporting specific crops and populations: 1. **Tierra Caliente (Hot Land)**: - Elevation: Sea level to 3,000 feet. - Climate: Hot and tropical. - Crops: Cocoa, bananas, sugarcane. - Ecosystem: Tropical rainforests. 2. **Tierra Templada (Temperate Land)**: - Elevation: 3,000 to 6,500 feet. - Climate: Spring-like year-round. - Crops: Corn, beans, squash, coffee. - Population: Densely populated. 3. **Tierra Fría (Cold Land)**: - Elevation: 6,500 to 12,000 feet. - Climate: Cool. - Crops: Wheat, potatoes. - Population: Major cities like Quito and Lima. 4. **Tierra Helada (Frozen Land)**: - Elevation: Above 12,000 feet. - Climate: Snow and glaciers. - Crops: Limited cultivation. These zones influence where people live and what they grow, making the Andes a hub of agricultural diversity. In Tierra Templada, coffee thrives due to the mild climate, making it a key export for countries like Colombia. --- ## Natural Hazards ### El Niño Phenomenon - **What is El Niño?** - A warming of ocean surface waters along the coasts of Ecuador and Peru, occurring every 2–7 years. - Named "El Niño" (The Christ Child) because it typically appears around December. - **Mechanism**: - Normal air circulation (clockwise) is disrupted, creating two convection cells. - Warm air and water are pushed toward Peru, altering weather patterns globally. - **Impacts**: - Increased rainfall in typically dry areas (e.g., Peru). - Drought in normally wet regions (e.g., Amazon). - Warmer ocean temperatures in North America, leading to more hurricanes. El Niño can cause extreme weather events, such as flooding in South America and droughts in Southeast Asia. Confusing El Niño with La Niña. La Niña is the opposite phenomenon, characterized by cooler ocean temperatures. --- ## Rain Shadow Effect ### The Atacama Desert - **Formation**: - Warm, moist air from the Pacific is forced upward by the Andes. - As the air rises, it cools and releases moisture on the windward side (orographic precipitation). - The dry air descends on the leeward side, creating arid conditions (rain shadow). - **Result**: - The Atacama Desert in northern Chile is one of the driest places on Earth. The lush forests on the windward side of the Andes contrast sharply with the barren Atacama Desert on the leeward side. The Peru Current also contributes to the Atacama's dryness by cooling the air and reducing evaporation. --- ## Environmental Challenges ### Deforestation in the Amazon - **Causes**: - Historically: Subsistence farming. - Modern drivers: Cattle ranching (75% of deforestation), soybean farming, and road construction. - **Consequences**: - Loss of biodiversity. - Release of stored carbon, contributing to global warming. - Disruption of the Amazon's role as a "water pump," affecting rainfall patterns in Brazil. Deforested land converted to cattle ranching yields only $60 per acre, compared to $2,400 per acre if sustainably managed. Sustainable forest management can balance economic needs with environmental preservation. --- ## Water Scarcity ### Case Study: São Paulo, Brazil - **Paradox**: - Brazil holds 12% of the world's freshwater, yet São Paulo faces water shortages. - **Reasons**: 1. **Uneven Distribution**: - The Amazon Basin contains 50% of Brazil's water but only 4% of its population. - Coastal megacities like São Paulo rely on stressed local river basins. 2. **Deforestation**: - Loss of Amazonian trees disrupts the water cycle, reducing rainfall in southern Brazil. 3. **Urbanization**: - Rapid growth outpaces infrastructure development. Deforestation in the Amazon not only affects biodiversity but also exacerbates water scarcity in urban areas. --- ## Historical and Human Patterns ### Pre-Colonial Civilizations - **Aztecs and Incas**: - Advanced technologies rivaled European systems (e.g., sewage systems, urban waterworks). - The Inca Empire (largest in the Americas) spanned from southern Colombia to northern Chile and Argentina. ### Colonial Impact - **Population Decline**: - Indigenous populations reduced by 90% due to disease and exploitation. - **Economic Dependency**: - Colonies could only trade with Spain or Portugal, fostering dependency. - **Enslavement**: - Millions of Africans were enslaved and brought to the Americas to replace the declining indigenous workforce. Assuming colonial systems were entirely dismantled post-independence. Many corrupt practices persist today. Understanding colonial history helps explain modern economic and political challenges in the region. --- ## Key Takeaways 1. The Amazon Basin is vital for global biodiversity, carbon absorption, and water regulation. 2. Altitudinal zones in the Andes shape agriculture and settlement patterns. 3. El Niño and the rain shadow effect significantly influence regional climates. 4. Deforestation and urbanization exacerbate environmental and water crises. 5. Colonial legacies continue to impact governance and development in Middle and South America. Practice Question: How does the rain shadow effect contribute to the formation of the Atacama Desert?