1. Greenhouse Effect

2. Greenhouse Effect Without climate system, Earth much colder than it is
Climate system traps Sun’s energy; distributes heat around world
Warming process called ‘Greenhouse Effect’
Recall: UV from sun; IR from ground
Greenhouse gases in atmosphere absorb radiation from Earth’s surface and radiate it out in all directions
Half of IR radiation sent back to Earth

4. Greenhouse Gases Air mostly N and O – don’t absorb radiation
Gases that do absorb IR are called greenhouse gases (mostly H2O and CO2)
Also methane (CH4) , ozone (O3) and nitrous oxide (N2O)

6. Carbon Dioxide Atmosphere contains 385ppm CO2 (0.0385% of gases)
Estimated to cause up to a quarter of natural greenhouse effect on Earth – volcanoes, burning, cellular respiration of plants and animals

7. Carbon Cycle Movement of C through living things
Oceans and living things remove CO2 from atmosphere and store C atoms in different form – called carbon sinks
Eg. Plants use CO2 in photosynthesis; ocean sediment is solid calcium carbonate (like in seashells)

9. Water Vapour Causes roughly two-thirds of natural greenhouse effect
Quantity depends on temperature – up to 4%
Higher temp., more water vapour in atmosphere
Relationship called a feedback loop

10. Greenhouse Effect How do greenhouse gases trap IR?
N and O are diatomic atoms (2 of same atom); vibrate back and forth
Water, carbon dioxide and methane have 3 or more atoms; wiggle in many ways and hit more energy waves