C13 - The Earth's Atmosphere Flashcards
What is the atmosphere made up of today
- Around 80% N₂
- Around 20% O₂
- 0.9% Argon
- 0.04% CO₂
- Trace other gases
Common theory for how the early atmosphere was formed
Intense volcanic activity released gases
What was the early atmosphere composed of and what was it like
- Some N₂, other amounts of CO₂ and H₂O
- Trace amounts of NH3 and CH4
- Similar to atmosphere of Mars or Venus
How were the oceans formed?
- The Earth cooled down
- This condensed the water vapour in the atmosphere
Also allowed plants to grow
How did Oxygen levels in the atmosphere increase
- Plants and algae photosynthesised
- This produced O₂
How did CO₂ levels in the atmosphere decrease
- Dissolved in oceans forming carbonates and then precipitated to form sedimentary
- Micro-organisms died and fell into sediment, forming carbon fossil fuels
- Plants and algae photosynthesised
How did ammonia and methane levels in the atmosphere decrease
- They reacted with oxygen to form either CO₂ and water vapour or N₂ and water vapour
How was coal formed
- Ferns and trees die in wetlands
- The conditions prevented oxidation
- High pressure and temp. formed coal
How was crude oil and natural gas formed
- Micro-organisms (plankton) died in the sea
- Their remains got buried by sediment (lack of O₂)
Name 3 Greenhouse Gases
- Co₂
- Methane
- Water Vapour
Describe the greehouse effect
- Shortwave radiation from Sun passes through atmosphere
- Earth absorbs these and then radiates them as longwave IR
- This is absorbed by greenhouse gases and emitted back down which warms the atmosphere
Human activities that increase Co₂
- Burning fossil fuels
- Deforestation
Human activities that increase methane
- Growing rice in flooded paddy fields
- Cattle farming
Effects of climate change
- Melting ice caps + rising sea levels
- Extreme weather
- Famine + drought
- Distribution change in animals (migration)
- Loss of biodiversity and habitat
Why do many scientists believe in climate change
- Evidence is shared between them
- This is a peer review process and it avoids false claims or bias
Why is information about climate change hard to communicate
- It is hard to model and there are uncertanties e.g. how much the temperature will rise
- This means it has to be simplified for the general public
- This can lead to bias or speculation
Defenition of a carbon footprint
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
Ways to reduce carbon footprint
- Insulating homes
- Using public transport
- Renewable electricity sources
- Eat less beef and dairy
- Trapping methane
Problems with reducing carbon footprint
- Solutions are expensive
- Can be inconvenient
What is carbon monoxide and how is it formed
- It is a toxic, colourless gas
- Formed from incomplete combustion
How is sulfur dioxide formed
- Some fuels have sulfur in them
- this is then oxidised
How are oxides of nitrogen formed
- High pressure and temperature inside diesel engines
Problems with sulfur dioxide and oxides of nitrogen
- Cause respiratory problems
- Form acid rain which damages infrastructure and kills organisms
How are particulates formed and problems with them
- Unburned hydrocarbons and carbon in engines
- This is due to incomplete combustion due to insufficient oxygen
- Cause health problems such as heart disease
- Cause global dimming which affetcs rainfall patterns
Problems with increased carbon dixoide emissions
- It is a greenhose gas so traps more heat increasing teh surface temperature
- This causes global warming and clomate change
- Leads to polar ice caps melting, sea levels rising
- Leads to flooding + other extreme weather events (droughts)
- Reduction in biodiversity
