Topic 4 - Earth Science Flashcards
What was the early atmosphere like 4 billion years ago?
Earth covered in volcanoes
• Little or no oxygen
• Water vapour
• A large amount of Carbon dioxide
Small amounts of other gasses:
• Ammonia
• Methane
• Nitrogen
What is the earth like now?
Earth has oceans on surface.
Main gasses now:
• Nitrogen 78%
• Oxygen 21%
• Very small amount of carbon dioxide 0.04% and water vapour
• Argon 0.9%
What is the evidence for the early atmosphere?
1) The earliest known rocks contain iron compounds that form with no oxygen around
2) Oldest fossil fuels date from 3 billion years ago (when oxygen production by organisms started)
3) Rocks contain different types of iron oxides that form when much more oxygen is present
4) Atmospheres of other planets today, which have not been changed by living organisms
5) The mixture of gasses released by volcanoes
How did carbon dioxide go and oxygen come?
• Volcanic activity let out carbon dioxide and heat
• Earth was very hot
• No plant or animal life
• As planet cooled water vapour condensed to form oceans
• Life forms evolved in the oceans
• CO2 is soluble and dissolved in oceans
• Photosynthesis takes in CO2 and releases oxygen
• Other animals were able to evolve with the oxygen released
What is global warming?
Long term heating of the earths climate.
What is climate change?
Changes to average weather conditions around the world.
What is the greenhouse effect - definition?
The way in which heat is trapped close to the earths surface.
What is the greenhouse effect?
1) Energy (infrared radiation) is transferred to the earth
2) Some energy us absorbed by the earths surface warming it up
3) The warm earth emits infrared waves
4) Some gasses in the atmosphere absorb energy transferred by these infrared waves
5) When the gasses re-emit energy, some of it goes back to the earths surface and warms it, some goes into space
What are greenhouse gasses?
Gasses in the atmosphere that absorb energy
• Carbon dioxide
• Methane
• Water vapour
What is the evidence for global warming?
1) Ice core data - bubbles in ice cores have gasses from atmospheres thousands of years ago. Can analyse composition of gas and show that carbon dioxide has increased.
2) Lab experiments - these show that carbon dioxide absorbs infrared radiation so the detector doesn’t detect it.
3) Weather and temperature records - show that average temperatures are going up. They show a warming effect is happening.
What are the causes of climate change?
• Production and burning of fossil fuels —> CO2
• Deforestation —> CO2
• Live stock farming —> Methane
• Rice paddy farming —> Methane
What are the effects of climate change?
• Extinction
• Flooding
• Drought
• Rising sea levels
• Loss of land
What are the resolutions for climate change?
• Flood defences
• Plant more trees
• Eat less meat
• Reduce burning of fossil fuels
What is the chemical test from oxygen?
If a glowing splint re-ignites the gas is oxygen.
