Lecture 8 Climate & Ecosystem Diversity

Introduction to Environmental Systems Lecture 8

• Date: January 24, 2025

• Topic: Climate & Ecosystem Biodiversity (Part I)

Course Feedback

• Survey on course difficulty:

  • Too easy: 33.3%

  • Appropriate level of difficulty for an intro class: 33.3%

  • Too hard: 33.3%

• Optional feedback survey available in Canvas under Lecture 7.

Climate Overview

• Earth's climates are influenced by:

  • Solar energy

  • Earth's rotation

  • Greenhouse gases

  • Global air circulation

  • Surface features

  • Ocean currents

• Difference between weather and climate:

  • Weather: Short-term atmospheric changes (daily)

  • Climate: Long-term atmospheric patterns (30 years to thousands of years)

• Climate zones determined by temperature and precipitation averages.

• Upwelling: Nutrient-rich cold water rises from ocean depths, crucial for coastal ecosystems.

Air Circulation and Ocean Currents

• Climate variation caused by air circulation patterns and ocean currents:

  • Air circulation factors:

    • Uneven solar heating

    • Earth's rotation

    • Properties of air, water, land

• Prevailing winds: Help in distributing heat and moisture across the atmosphere.

Link Between Oceans and Atmosphere

• Ocean currents driven by winds; ocean heat influences atmospheric circulation.

• El Niño-Southern Oscillation (ENSO): Occurs every few years; impacts global weather patterns.

  • Weakened eastern Pacific winds affect large-scale weather for 1-2 years.

ENSO Diagnostic Discussion

• ENSO Alert Status: La Niña conditions present, likely to persist into early 2025.

• La Niña Characteristics:

  • Below-average sea surface temperatures (SSTS) in the equatorial Pacific.

  • Low-level easterly wind anomalies and upper-level westerly wind anomalies lead to altered weather patterns.

• El Niño Characteristics:

  • Weaker surface winds; warmer ocean temperatures in central/east Pacific; increased rainfall in these areas.

  • Changes in rising and sinking air cause varied surface pressures.

Impact of Earth's Geography on Climate

• Mountainous terrain can create weather effects via the rain shadow effect.

• Urban heat islands caused by cities absorbing heat, impacting local climates.

  • Heat island causes:

    • Reduced natural landscapes

    • Human activity (vehicles, AC)

  • Impacts: Increased energy consumption, pollution, impaired water quality, and health effects.

Terrestrial Ecosystems and Climate

• Climate is a determinant of biome and ecosystem location:

  • Major ecosystems include deserts, grasslands, and forests.

  • Influences: Temperature, precipitation patterns, and air circulation.

• Biomes are regions defined by climate and dominant vegetation.

Types of Deserts

• Three major types of deserts based on temperature and low annual precipitation:

  • Tropical: (e.g., Sahara Desert)

  • Temperate: (e.g., Mojave Desert)

  • Cold: (e.g., Gobi Desert)

• Fragile ecosystems with slow nutrient cycling; survival adaptations focus on water conservation.

Types of Grasslands

• Types of grasslands:

  • Tropical: (e.g., East African savannas)

  • Temperate: (many converted to farmland)

  • Cold: (arctic tundra)

• Monoculture farming is less sustainable compared to high-biodiversity grasslands.

Types of Forests

• Tropical forests: High productivity and biodiversity with vulnerable thin topsoil.

• Temperate forests: Deciduous and coniferous with higher nutrient storage due to slower decomposition.

• Cold forests: Limited sunlight, cold winters, and different ecological dynamics.

Ecological Roles of Mountains

• Essential source of fresh water for millions (e.g., California's water from Sierra snowpack).

• Biodiversity sanctuaries often contain endemic species vulnerable to climate change.

Human Impact on Terrestrial Ecosystems

• Roughly 60% of terrestrial ecosystems are degraded or used unsustainably, raising concerns about future ecological and economic stability.

Marine Ecosystems and Human Activity

• Oceans harbor significant biodiversity and provide critical ecosystem services.

• Aquatic Life Zones: Distinguished by saltwater (marine) and freshwater ecosystems, affected by various environmental factors (temperature, oxygen availability).

• Three major marine life zones:

  • Coastal zones (estuaries, coastal wetlands)

  • Open ocean (varying depths)

  • The ocean bottom (benthic)

Ecosystem Services Provided by Oceans

• Coastal ecosystems filter pollutants and support fisheries and biodiversity.

• Protect against coastal erosion and storm damage.

Lecture 8 Key Takeaways

• long-term climate differences dictate earth's biomes (deserts, grasslands, forests).

• Saltwater and freshwater cover nearly three-fourths of Earth’s surface with oceans being predominant.

• Human activity is significantly disrupting the critical services provided by both terrestrial and aquatic ecosystems.