Chemistry of the atmosphere

• Phase 1- volcanoes gave out gases


  in the first billion years of Earth's history were pretty explosive- the surface was covered in volcanoes that erupted and released lots of gases. the early atmosphere was mostly made up of carbon dioxide with virtually no oxygen

  volcanic activity also released nitrogen which built up in the atmosphere over time as well as water vapour and small amount of methane and ammonia
• Phase 2- oceans, algae and green plants


  when the water vapour in the atmosphere condensed, oceans were formed. lots of carbon dioxide was removed from the atmosphere as it dissolved in the oceans. this formed carbonate precipitates that formed sediments on the seabed. marine animals evolved- their shells and skeletons were made from carbonates from the oceans. green plants and algae evolved and absorbed carbon dioxide so they can photosynthesise
• Carbon getting trapped in fossil fuels and rocks

  1. Plants, plankton and marine animals die

  2. They fall to the seabed

  3. Get buried by layers of sediment

  4. Compressed over millions of years

  5. Form sedimentary rocks, oil, and gas
• Fossil fuels


  Coal, crude oil and natural gas made by the process of carbon getting trapped in sedimentary rocks
• Crude oil and natural gas

  Formed from deposits of plankton trapped in rock under the seabed
• Coal


  A sedimentary rock made from plant deposit
• Limestone


  A sedimentary rock made of calcium carbonate from shells and skeletons of marine animals
• Phase 3- green plants and algae produce oxygen


  algae evolved first- 2.7 billion years ago and then green plants evolved

  as oxygen built up in the atmosphere over time, more complex life could evolve

  about 200 million years ago, the atmosphere reached a composition similar to how it is today- 80% nitrogen, 20% oxygen
• greenhouse effect


  greenhouse gases act like an insulating layer on earth, they don't absorb the incoming short wavelength radiation from the Sun but do absorb the long wave wavelength radiation that gets reflected back off the earth and re-radiate it in all directions

  the longwave radiation is thermal radiation, which results in the warming of the earth.
• human activity can increase the amount of greenhouse gases in the atmosphere

  deforestation- less trees remove co2 via photosynthesis

  burning fossil fuels- carbon that was locked up is released as co2

  agriculture- more farm animals produce methane through digestion

  creating waste- more landfill sites and more waste from agriculture means more co2 and methane released by decomposition of waste
• increasing carbon dioxide levels is linked to climate change

  the earth's temperature increases naturally

  the average temperature is increasing greater than expected naturally

  hard to fully understand the earth's atmosphere as things are very complicated. led to speculation about the accuracy of carbon dioxide causing climate change to grow at an increased rate
• climate change can have dangerous consequences

  increase in global temperature can lead to ice caps melting causing a rise in flooding and costal erosion

  change in rainfall patterns can cause regions to get too much or too little rainfall which can damage the ability to produce food

  the severity of storms may also increase

  changes in temperature and amount of water can affect animal species distribution and affect their habitats
• carbon footprints


  carbon footprints are a measure of the amount of carbon dioxide and other greenhouse gases released over the full life cycle

  measuring the carbon footprint of something can be very hard because there are many different factors to consider- manufacturing, making, use, disposition

  a rough calculation can be made to give an idea of the worst emitters
• reducing a carbon footprint

  renewable energy sources or nuclear energy can be used instead of fossil fuels. more efficient processes could conserve energy and waste

  governments can tax companies that use an excessive amount of greenhouse gases and can put a cap on emissions

  technology that captures the co2 produced by fossil fuels before it is released into the atmosphere and then can be stored underground
• carbon footprint 


  carbon capture and storage is a relatively new idea and technology is still at the developmental stage

  reducing carbon dioxide emission could harm economic growth

  because not everyone agrees international cooperation is difficult

  there is little education making it hard for individuals to change their lives
• combustion of fossil fuels releases gases and particles 


  fossil fuels contain hydrocarbons, during combustion these are oxidised

  if there is incomplete combustion, some of the fuel does not burn, releasing particulates, made of soot
• particulates


  if particulates are inhaled, they can get stuck in the lungs and cause damage, leading to respiratory problems

  they are bad for the environment as they reflect sunlight back into space, meaning less sunlight reaches the earth, resulting in global dimming
• carbon monoxide 


  carbon monoxide is dangerous because it can bind to haemoglobin resulting in less oxygen travelling round the body

  a lack of oxygen can lead to fainting, a coma, or death

  carbon monoxide doesn't have a colour or smell so it can be very hard to detect, making it particularly dangerous