Rucete ✏ Campbell Biology In a Nutshell
Unit 8 ECOLOGY — Concept 52.1 Earth’s Climate Varies by Latitude and Season and Is Changing Rapidly
The long-term climate of a region—determined by temperature, precipitation, sunlight, and wind—has the most significant influence on where organisms live. These global patterns are shaped by solar input, Earth's movement, and geography, and are being rapidly altered by human-driven climate change.
1. Global Climate Patterns
- Driven by solar energy input and Earth’s rotation and orbit
- Uneven heating causes latitudinal temperature gradients
- Warm air rises at the equator, cools, and releases moisture → tropical rain
- Dry descending air around 30° N and S forms deserts
- Global air circulation and ocean currents distribute heat and moisture
2. Seasonality
- Caused by Earth’s tilted axis and orbit around the sun
- Leads to variation in day length, solar radiation, and temperature
- Wet and dry seasons in tropics arise from shifting air circulation bands
- Seasonal winds can drive upwelling of nutrient-rich water → supports fisheries
3. Bodies of Water
- Oceans and lakes moderate climate due to high specific heat of water
- Currents warm or cool nearby coasts (e.g., Gulf Stream warms Europe)
- Coastal climates are wetter than inland areas
- Local breezes arise as air moves between land and water
4. Mountains
- Mountains alter airflow and precipitation patterns
- Windward side: moist air rises, cools, and causes rain
- Leeward side: dry air descends → rain shadow effect
- Elevation cools climate (~6°C drop per 1,000 m rise)
- Sunlight exposure varies by slope (south-facing is warmer in N. Hemisphere)
5. Vegetation Effects
- Forests absorb solar energy and increase transpiration → cooling and moistening climate
- Deforestation leads to warmer, drier conditions
- Reforestation brings cooler, wetter microclimates
- Vegetation alters local energy and water cycles significantly
6. Microclimates
- Created by shade, wind, soil moisture, and elevation
- Forest interiors stay cooler and moister than open areas
- Logs, rocks, and canopy offer thermal protection for small organisms
7. Global Climate Change
- Fossil fuel burning and deforestation raise greenhouse gas levels → global warming
- Global temp ↑ ~0.9°C since 1900; projected ↑ 1–6°C by 2100
- Shifts wind/rain patterns and increases extreme weather events
- Species migration examples:
- European butterflies moved 35–240 km north
- Plants migrate uphill
- Diatoms colonized new oceans after 800,000 years
- Migration too slow for many species → extinction risk increases
In a Nutshell
Earth’s climate is shaped by global solar patterns and modified by local factors like water, mountains, and vegetation. These elements define habitats and species distributions. Today, climate is changing rapidly due to human activity, forcing many organisms to shift their ranges or face extinction as temperatures rise and weather patterns shift.