1.2 Natural Climate Change Flashcards
What does natural climate change refer to?
Natural climate change refers of how the climate conditions vary over time.
How long do glacial periods last for?
Around 100,000 years
How long do interglacial periods last for?
Around 10,000 years
What are the four main theories that climatologists use to explain why the climate has changed in the past.
- Obital changes
- Asteroid collisions
- Volcanic activity
- Solar output variation
What are orbital changes?
Orbital changes are a variation of in the way the earth moves around the sun. These changes may have caused the glacial and interglacial cycles during the quaternary period.
What are the 3 orbital changes?
Eccentricity
Obliquity/tilt
Precession
What is eccentricity?
The path of the Earth’s orbit around the sun changes from an almost perfect circle to an ellipse( an ovel) and back again every 96,000 years
What is obliquity / tilt?
The Earth’s axis is tilted at an angle as it orbits Sun. This tilt changes over a cycle of about 41,000 years.
Explain precession
The axis of the Earth wobbles lile a spinning top on a cycle of about 23,000 years.
How do asteroid collisions affect the climate?
- Asteroids hit the Earth’s surface throwing up dust into the atmosphere.
- Particles prevent the sun’s energy from reaching the Earth’s surface so global temperatures fall.
Explain how volcanic activity can affect the climate.
- Major volcanic eruptions ejecting large quantities of ash into the atmosphere.
- Some of these particles reflect the Sun’s rays back out to space so the Earth’s surface cools.
Explain how solar output variation affects the climate
- The Sun’s energy output isn’t constant as it changes in short cycles of about 11 years and possibly longer cycles of several hundred years.
- Periods of reduced solar output can cause the Earth’s climate to cool.
Give example evidence for climate change
Ice cores
Tree rings
Historical evidence - temperature logs
Pollen analysis
Explain how tree rings show evidence for natural climate change
As each ring shows a year of growth, changes in shape and size show the conditions during that year. - Warmer wetter weather is shown by greater growth as the ring is bigger.
- Cooler drier weather is shown by thinner rings.
Expalin how ice cores show evidence for natural climate change.
The ice contains bubbles of the air from each year. Scientists analyse the bubbles in each layer to see how much CO2 they contain. Ash and pollution can show what happened over the years.
Explain how historical sources show evidence for natural climate change.
Old photos, drawings, written records, diaries and the records of dates at regular intervals e.g. the harvests, the arrival of migrating birds and tree blossom. These sources are often not very accurate because they were not intended to record climate. However they can still give us some evidence of recent climate trends.
