C9 Flashcards
Describe 3 things about the earth 4.6 billion years ago.
- no life
- little oxygen
- lots of volcanic activity
- until eventually it decreased
What did the decrease in volcanic activity cause? How were ocean created?
the earth’s temperature dropped —> the earth cooled down
water vapour in the atmosphere condensed to water —> caused rain for many years —> creating oceans
—> caused CO2 in the atmosphere as CO2 dissolves in water —> forms limestone
How did oxygen levels later increase and CO2 levels drop?
green algae and plants developed photosynthesis which produced more oxygen and used more CO2
what is limestone?
a sedimentary rock that is often found at bottom of oceans or in a query
- used to make buildings or statues
what is limestone made from?
Marine organisms
what is oil made from?
dead sea organisms
which 2 gases did the early volcanic activity produce lots of?
CO2 and water vapour
- little nitrogen
which gas condensed to from oceans?
water vapour
which gas dissolved into the oceans?
CO2
what percentage did CO2 make up in the early atmosphere vs the modern atmosphere?
Early atmosphere: the vast majority
Modern atmosphere: 0.04%
what percentage did oxygen make up in the early atmosphere vs the modern atmosphere?
Early atmosphere: little/none
Modern atmosphere: 21%
what percentage did nitrogen make up in the early atmosphere vs the modern atmosphere?
Early atmosphere: Trace ( very little)
Modern atmosphere: 78%
what percentage did water vapour make up in the early atmosphere vs the modern atmosphere?
Early atmosphere: Lots
Modern atmosphere: Trace%
what percentage did ‘other gases’ make up in the early atmosphere vs the modern atmosphere?
Early atmosphere: Trace ( very little)
Modern atmosphere: Trace%
(ONA) Exam question: Describe and explain the changes in the composition of gases between the early atmosphere and the modern atmosphere
How are fossil fuels made?
sea organisms die and are compacted and pressured to form fossil fuels over millions of years
How is limestone made?
dead marine organisms die, sand and silt are compacted and pressured over millions of years
why is CO2 given off when fossil fuels are burnt?
the carbon in the organisms react with oxygen in the air to form CO2
what is the atmosphere?
layers of gases surrounding the earth
How GHGs make the earth warmer?
they absorb heat energy—> stops heart energy escaping into space –> so the earth gets warmer
what is it important to have some GHGs?
so the earth isn’t cold
Give 4 ways GHGs are produced?
- burning fossil fuels
- farming cattle
- rice fields
- rotting landfill
Exam question: why should you not leave a dog in the car?
Dogs respire, producing CO2 in the car —> the CO2 absorbs heat energy –> so the car heats up dramatically
Steps for the greenhouse effect (6)
- Electromagnetic radiation passes through the earth’s atmosphere
- The earth absorbs most of the radiation and warms up
- The earth radiates energy as infrared radiation
- Some of the infrared radiation goes into space
- Some of the infrared radiation is absorbed by GHGs in the atmosphere
- The atmosphere warms up
Exam question: Explain why scientists believe that rising CO2 levels are leading to an increase in global temperatures?
If CO2 levels increase more heat energy is absorbed and stops the infrared radiation from escaping to space so stays on earth and causes an increase in global temperatures
what is climate change?
a change to average global temperatures of the earth