❄️Earth Surface Processes Unit 14 – Human Impacts on Earth Processes

Key Concepts and Terminology

• Anthropocene refers to the current geological age viewed as the period during which human activity has been the dominant influence on climate and the environment
• Earth systems include the atmosphere, hydrosphere, biosphere, and geosphere which are interconnected and influenced by human activities
• Geomorphology studies the physical features of the Earth's surface and the processes that shape them such as erosion, deposition, and weathering
• Biogeochemical cycles describe the fluxes of chemical elements among different parts of the Earth (atmosphere, oceans, land, and living things)
  • Carbon cycle involves the exchange of carbon between the atmosphere, oceans, terrestrial biosphere, and geological deposits
  • Nitrogen cycle converts nitrogen between various chemical forms primarily through biological processes
• Ecosystem services are the direct and indirect contributions of ecosystems to human well-being (food, clean water, climate regulation)
• Sustainability aims to meet the needs of the present without compromising the ability of future generations to meet their own needs
• Anthropogenic forcing refers to human activities that change the Earth's energy balance and drive climate change (greenhouse gas emissions, land-use changes)

Natural Earth Surface Processes

• Plate tectonics drive the formation and movement of continents and oceanic crust resulting in mountain building, volcanic activity, and earthquakes
• Weathering breaks down rocks and minerals through physical, chemical, and biological processes
  • Physical weathering involves mechanical breakdown of rocks into smaller fragments without changing their chemical composition (frost wedging, abrasion)
  • Chemical weathering alters the chemical composition of rocks through reactions with water, air, or acids (dissolution, oxidation)
• Erosion is the removal and transport of weathered materials by water, wind, ice, or gravity
  • Fluvial erosion occurs through the action of rivers and streams (abrasion, hydraulic action)
  • Aeolian erosion is caused by wind (deflation, abrasion)
• Deposition is the settling of eroded sediments in new locations (floodplains, deltas, dunes)
• Mass wasting is the downslope movement of rock, soil, and debris under the influence of gravity (landslides, rockfalls)
• Glacial processes shape landscapes through erosion and deposition (U-shaped valleys, moraines)
• Coastal processes involve the interaction of waves, tides, and currents with shorelines (longshore drift, beach formation)

Human Activities Affecting Earth Systems

• Deforestation removes forest cover for agriculture, urbanization, or resource extraction disrupting ecosystems and altering climate
• Agricultural practices such as tillage, irrigation, and fertilizer use modify soil structure, hydrology, and nutrient cycling
  • Overgrazing can lead to soil erosion and desertification
  • Monoculture reduces biodiversity and increases vulnerability to pests and diseases
• Urbanization converts natural landscapes into built environments altering hydrology, biodiversity, and climate (urban heat island effect)
• Mining and resource extraction can cause land subsidence, water pollution, and habitat destruction
  • Mountaintop removal mining drastically alters topography and damages ecosystems
  • Oil spills contaminate marine and coastal environments
• Damming of rivers for hydropower, irrigation, or flood control disrupts natural flow regimes and sediment transport
• Groundwater extraction can lead to aquifer depletion, land subsidence, and saltwater intrusion
• Coastal development modifies shorelines through the construction of seawalls, jetties, and beach nourishment

Environmental Consequences

• Climate change driven by anthropogenic greenhouse gas emissions leads to rising temperatures, sea levels, and altered precipitation patterns
  • Melting glaciers and ice sheets contribute to sea-level rise and alter freshwater availability
  • Extreme weather events (droughts, floods, hurricanes) become more frequent and intense
• Soil degradation results from erosion, compaction, salinization, and loss of organic matter reducing fertility and productivity
• Desertification is the persistent degradation of dryland ecosystems due to human activities and climate variations
• Biodiversity loss occurs through habitat destruction, overexploitation, invasive species, and climate change
  • Deforestation in tropical rainforests threatens species richness and ecosystem services
  • Coral reef bleaching and degradation result from ocean warming and acidification
• Water pollution from agricultural runoff, industrial discharges, and sewage affects aquatic ecosystems and human health
• Air pollution, including particulate matter and ground-level ozone, impacts respiratory health and contributes to acid rain
• Land subsidence can damage infrastructure and increase flood risk in coastal and low-lying areas

Case Studies and Real-World Examples

• The Aral Sea in Central Asia has shrunk dramatically due to river diversions for irrigation leading to ecosystem collapse and health issues
• The Dust Bowl in the United States during the 1930s resulted from a combination of drought and unsustainable farming practices causing severe soil erosion
• The Three Gorges Dam in China, the world's largest hydroelectric project, has displaced communities, altered ecosystems, and increased landslide risk
• The Amazon rainforest, a biodiversity hotspot, is under threat from deforestation for cattle ranching, soybean cultivation, and logging
  • Deforestation in the Amazon contributes to carbon emissions and alters regional climate patterns
• The Maldives, a low-lying island nation, faces existential risk from sea-level rise and coral reef degradation
• The Deepwater Horizon oil spill in the Gulf of Mexico in 2010 was the largest marine oil spill in history impacting coastal ecosystems and economies
• The Sahel region in Africa experiences desertification and food insecurity exacerbated by overgrazing, deforestation, and climate variability

Measurement and Assessment Methods

• Remote sensing techniques (satellite imagery, aerial photography) monitor changes in land cover, vegetation health, and topography
  • Landsat and MODIS satellite data are used to map deforestation, urbanization, and land-use change
  • LiDAR (Light Detection and Ranging) provides high-resolution topographic data for studying geomorphology and erosion
• Geospatial analysis tools (GIS, GPS) integrate and visualize spatial data for environmental assessment and decision-making
• Field surveys and ground truthing validate remote sensing data and provide detailed site-specific information
• Soil and water quality testing assess the chemical, physical, and biological properties of these resources
• Ecological indicators (species richness, habitat quality) evaluate the health and integrity of ecosystems
• Carbon and greenhouse gas accounting quantify emissions from human activities and natural sources
• Environmental impact assessments evaluate the potential effects of proposed projects on the environment and communities

Mitigation and Sustainability Strategies

• Sustainable land management practices (conservation tillage, agroforestry) reduce soil erosion and improve soil health
• Ecosystem restoration and reforestation efforts aim to recover degraded habitats and enhance carbon sequestration
  • Mangrove restoration protects coastlines, supports biodiversity, and stores carbon
  • Grassland restoration in the Great Plains of North America reduces soil erosion and supports wildlife
• Protected areas and conservation corridors preserve biodiversity and maintain ecosystem services
• Sustainable water management (drip irrigation, rainwater harvesting) improves water-use efficiency and reduces depletion
• Urban green infrastructure (green roofs, permeable pavements) mitigates urban heat island effect and manages stormwater runoff
• Renewable energy transition reduces greenhouse gas emissions and dependence on fossil fuels
• Circular economy approaches minimize waste and promote resource efficiency through recycling and reuse
• Community-based natural resource management engages local communities in conservation and sustainable use of resources

Future Outlook and Challenges

• Climate change adaptation and resilience-building are critical for managing the impacts of a changing climate on Earth systems
  • Sea-level rise adaptation measures include coastal retreat, accommodation, and protection
  • Drought-resistant crops and water-saving technologies are needed for agricultural resilience
• Population growth and urbanization will continue to put pressure on natural resources and ecosystems
• Sustainable development goals (SDGs) provide a framework for integrating environmental, social, and economic objectives
• Transboundary cooperation is essential for managing shared resources (river basins, migratory species) and addressing global challenges
• Ecosystem-based approaches that value and work with nature are gaining recognition as cost-effective solutions
• Advances in technology (remote sensing, big data, artificial intelligence) offer new opportunities for monitoring and managing Earth systems
• Behavioral change and public awareness are crucial for driving sustainable consumption and production patterns
• Equitable distribution of costs and benefits is a key challenge in implementing sustainability strategies