chemistry of the atmosphere

• when was the earth formed?

  4.6 Billion years ago
• what did the earths atmosphere mostly consist of 4.6 Billion years ago?

  Co2
• what started to increase in the atmosphere ?

  oxygen and nitrogen
• what gas is the majority of our atmosphere?

  nitrogen
• why did the atmosphere change?

  -intense volcanic activity

  -green plants and algae evolved
• what effect does evolving green plants and algae have on the atmosphere?

  -carbon dioxide is reduced as the plants take it in and give out oxygen.

  -micro-organisms that cant tolerate oxygen are killed off

  -carbon from co2 becomes locked up in sedimentary rocks formed from the shells and skeletons of marine organisms.
• what effect does the intense volcanic activity have on the atmosphere?

  -releases mainly co2

  -releases water vapour, which condenses to form the oceans

  -releases small proportions of methane and ammonia
• what is the earths atmosphere like today?

  -20% oxygen

  -80% nitrogen

  -amount of co2 has decreased significantly
• why has there been an increase in oxygen?

  Algae and plants photosynthesising
• what is the products of photosynthesis?

  Glucose and water
• what are the reactants of photosynthesis

  carbon dioxide and water
• how long has the earths atmosphere been roughly the same for?

  200 million years
• when did algae start producing oxygen?

  2.7 billion years ago
• why did animals manage to evolve?

  Levels of oxygen increased
• why did the level of co2 decrease?

  -plants and algae evolved

  -carbon has become locked up in sedimentary rocks and fossil fuels

  -reaction between co2 and sea water
• what is an example of a sedimentary rock?

  -limestone

  -coal
• what does limestone contain?

  Calcium carbonate which can be formed from the shells and skeletons of sea creatures
• how is coal formed?

  Plant deposits that were buried and compressed over millions of years
• why may too much co2 dissolving into the sea be bad?

  Harm marine life, such as coral reefs
• what does the reaction between co2 and sea water produce?

  -insoluble carbonates that are deposited as sediment

  -soluble hydrogen carbonates
• what are examples of greenhouse gases?

  -co2

  -methane

  -water vapour
• what radiation is absorbed by earth?

  infrared
• what must the radiation have for it to be absorbed not reflected by earth?

  High energy, short wavelength
• why may some infrared radiation be reflected?

  if the infrared radiation has lower energy and a longer wavelength
• what happens when earths greenhouse gases absorbs infrared radiation?

  increases earths temperature
• what could happen without greenhouse gases?

  Earth would be too cold for water to be a liquid and would not be able to support life
• what absorbs infrared radiation?

  greenhouse gases
• what human activities increase the levels of greenhouse gases?

  -burning fossil fuels

  -deforestation

  -decomposition of rubbish in landfill sites

  -increase in animal farming
• why does burning fossil fuels increase the levels of greenhouse gases?

  Fossil fuels contain carbon which has been locked up for millions of years, burning them will release co2.
• why does deforestation increase the levels of greenhouse gases?

  Leads to fewer trees taking up the gas for photosynthesis
• what 2 ways specifically increase methane levels?

  -decomposition of rubbish in landfill sites

  -increase in animal farming as methane is produced during animals digestion and by the decomposition of their waste
• what will be effected if the earths temperature increases?

  Result in a global climate change
• why is it hard for scientists to produce an accurate model?

  Lots of different factors involved makes it a complicated system
• why may models not be accurate?

  -oversimplification

  -inaccurate

  -biased
• what may happen if the global temperature increases?

  -a rise in sea levels which could cause floods and coastal erosion

  -more frequent and severe storms

  -changes in the amount and timing of rainfall

  -increased number of heatwaves which may be harmful to people and wildlife

  -more droughts

  -changes to the distribution of plants and animals as some areas may become inhabitable

  -food shortages due to changes in amount of food a country can produce
• what is a carbon footprint?

  The total amount of co2 and other greenhouse gases that are emitted over somethings full life cycle
• how can a carbon footprint be reduced?

  -using more alternative energy supplies such as solar power

  -wasting less energy

  -carbon capture and storage to prevent co2 being released

  -carbon taxes and licences

  -carbon off-setting through activities such as tree planting

  -encouraging people to choose carbon-neutral products
• why may there be problems on reducing a carbon footprint?

  -disagreements between scientists over the causes and consequences of global climate change

  -lack of information and knowledge

  -reluctance of people to make lifestyle changes

  -economic considerations (high cost of producing electricity from alternative resources)

  -disagreements between countries as to what should be done