Chemistry of the atmosphere

• Earth's early atmosphere - early existence of volcanoes

  For the first billion years of the earths existence, highly active volcanoes populated the surface

  The volcanoes frequently erupted. This released CO2

  Scientists think CO2 dominated the early atmosphere in a similar way to modern-day mars and Venus
• Later existence - oceans

  The volcanic activity also released:

  Nitrogen which slowly built-up in the atmosphere

  Water vapour which condensed to form oceans as well as smaller quantities of methane and ammonia

  The formation of oceans removed CO2 from the atmosphere

  Some of the dissolved carbon dioxide reacted with the seawater to produce carbonate precipitates these were deposited as sediment
• The rise of oxygen in the Earth's atmosphere

  Photosynthesis converts CO2 and H2O into Glucose and H2O

  Algae were the first photosynthetic organisms so evolve approximately 2.7 billion years ago

  Over the next billion years, photosynthesising plants began to evolve leading to an increasing rate of oxygen

  Eventually a threshold concentration o oxygen was reached which allowed more complex life forms to evolve, such as animals
• Oceans role in decrease CO2 in the atmosphere 


  The formation of oceans removed large amounts of CO2 from the atmosphere

  Once dissolved in the oceans, some of this carbon dioxide reacted with seawater to give carbonate precipitates
• Photosynthesis role in decreasing CO2 in the atmosphere

  CO2 is one of the reactants of the equation for photosynthesis

  Therefore photosynthetic action of algae and plants removed CO2 from the atmosphere
• Marine animals role in reducing CO2 in the atmosphere 


  Marine animals evolved. This removed carbonates from the oceans as the animals used there to build their shells and skeletons
• Human activities that increase the concentration of greenhouse gases in the atmosphere

  Burning fossil fuels - releases carbon dioxide

  Deforestation - less photosynthesis so less CO2 being removed from the atmosphere

  Landfills sites - The number and sizes of landfills increasing so more mounds of waste decomposing there more methane being released

  Agriculture - some farm animals release methane during digestion
• Although the earths temperature naturally changes, the recent increase in temperature is connected to increasing atmospheric greenhouse gas concentrations
• • The current scientific consensus is that increased greenhouse gas emissions caused by changes to human activity will lead to global climate change
  • This consensus is based upon peer-reviewed evidence
• The global climate system is very complicated making it difficult to create accurate models.

  Because of this, people speculate about climate change based on simple models and inadequate information
• Some people may have reasons to play down the contribution of greenhouse gas emissions to climate change

  If these biased opinions are published in the media misinformation can spread
• Climate change consequences

  • Melting of polar ice caps - sea levels rising
  • Meteorological events becoming more severe
  • Changes in water availability
  • Changes in precipitation (rain)
  • Food shortages
• Carbon footprint 


  Aa carbon footprint is a measure of the total amount of greenhouse gases emitted as a result of a particular service, event or product
• How individuals can reduce carbon footprint

  Maximising the efficiency of their energy use

  Minimising their waste

  Using renewable energy resources
• How governments can reduce carbon footprints

  Emission-based taxes

  Emission caps

  Emissions licenses up to a certain cap, these must be bought
• Carbon capture and storage

  Carbon dioxide, produced by burning fossil fuels is captured before its released into the atmosphere

  The captured carbon is stored deep underground
• Carbon off-setting 


  We can compensate emissions by planting trees. Trees remove CO2 from the atmosphere through photosynthesis
• Carbon neutral products 


  Carbon-neutral products don't change the atmospheric carbon dioxide concentration
• Scientific Barriers to reducing Carbon Footprint

  Scientists don't agree on the causes and consequences of climate change

  This is preventing scientists from making significant advances
• Economic barriers to reducing Carbon Footprint

  Many governments worry that making the required changes may restrict the economic development of their country

  This attitude is most common in developing countries
• Political barriers to reducing carbon footprint

  Countries have different opinions about the right course of action

  This spreads uncertainty. Countries aren't sure what other countries would do when presented with a potential international agreement

  Therefore countries hesitate to sign anything
• Social barriers to reducing Carbon footprint

  People in developed countries may not want to change their lifestyle

  Some societies don't make progress as their people are not educated on the importance of changing lifestyles
• Incomplete combustion - Atmospheric pollutants

  Incomplete combustion happens when fuels are burned in insufficient oxygen. It produces 2 problematic by-products

  • Carbon monoxide - a toxic gas
  • Particulates - small solid particles containing carbon and unburnt fuel
• Sulfur impurities - Atmospheric pollutants

  Sulfur is an impurity that is present in all fossil fuels

  Sulfur oxidises when burned. This produces the toxic gas sulfur dioxide
• Internal combustion engines in cars - atmospheric pollutants


  When fossil fuels are burned in a confined space, the high temperature can cause nitrogen and oxygen to react

  Leading to the formation of toxic nitrogen oxides
• Consequences of Carbon monoxide (CO)

  Binds to haemoglobin in the blood restricting bodies ability to transfer oxygen around the body

  Odourless and colourless making it difficult to detect

  CO poisoning can lead to fainting, comas or even death
• Consequences of Particulates 


  Inhaling particulates can cause respiratory problems

  Particulates reflect incoming radiation back into space causing global dimming

  Global dimming decreases the levels of sunlight available for photosynthesis. This can have knock-on effects for rainfall patterns
• Sulfur dioxide

  Inhaling sulfur dioxide can cause respiratory problems

  Sulfur dioxide can react with water to form sulfuric acid. Sulfuric acid is a major component of acid ran which can cause:

  Steel corrosion and the weathering of buildings and statues

  Insects, plants and aquatic organisms to die
• Nitrogen oxides 


  Inhaling nitrogen oxides can cause respiratory problems

  Nitrogen oxides can react with water to form nitric acid. Major components of acid rain which can cause:

  Steel corrosion and the weathering of buildings and statues Insects, plants and aquatic organisms to die