Earth and Space Science / Unit 8: Climate
8.4 Natural Climate Change
Notes
Climate has always changed because of natural causes.
- Milankovitch cycles: changes in Earth's orbit shape, axial tilt and wobble over 20,000 to 100,000 years drive ice ages.
- Solar output varies slightly.
- Volcanic eruptions release ash and sulfur dioxide that reflect sunlight and cool Earth for 1-3 years.
- Plate tectonics shifts continents and ocean currents over millions of years.
- Ice ages are cold periods with large ice sheets; glacials alternate with warmer interglacials.
Practice
Which natural cause changes climate over tens of thousands of years?
Orbital changes alter sunlight distribution.
A very large volcanic eruption often causes global:
Sulfur aerosols reflect sunlight.
Ice ages are best explained by:
Orbital changes plus feedbacks control glacial cycles.
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