3.4 Greenhouse Effect & Climate Change

Greenhouse Effect

NATURAL process: greenhouse gases trap heat → keeps Earth ~33°C warmer than it would otherwise be. Essential for life!

Greenhouse Gases

CO2, methane (CH4), water vapor, nitrous oxide. Trap outgoing infrared radiation.

Enhanced Greenhouse Effect

HUMAN activities (burning fossil fuels, deforestation) → increased CO2 → more heat trapped → global warming.

Global Warming

Earth has warmed ~1.1°C since pre-industrial times. Caused by human greenhouse gas emissions.

Climate Change

Long-term shifts: rising seas, more extreme weather, melting ice caps, shifting ecosystems.

Fossil Fuels

Coal, oil, natural gas; formed from ancient organisms. Burning releases 'ancient carbon' stored for millions of years into atmosphere.

Sea Level Rise

Caused by: (1) melting glaciers/ice sheets, (2) thermal expansion of warming ocean water.

Carbon Footprint

Total greenhouse gases produced by a person/organization. Reduced by renewable energy, less driving, less meat.