6.9A Future Emissions

• Future Uncertainties:

  • There are many uncertainties about future global warming and contributing natural and human factors
  • Uncertainty about natural factors include:
  • The role of carbon sinks and their capacity to cope with changes
  • Possible feedback mechanisms such as carbon release from peatlands and permafrost
  • Tipping points associated with forest dieback and the reversal of thermohaline circulation
• Future uncertainties:

  • Uncertainty about human factors include:
  • Future rates of global economic and population growth
  • Planned reduction in global carbon emissions
  • Exploitation of renewable energy sources
• Natural Factors:

  • Research has been conducted to see what the future changes to carbon stores may be with increasing carbon emissions
• Terrestrial carbon sinks:

  • Modelled to increase until 2050
  • When saturation is reached, they begin to act as sources:

  ->Thawing of permafrost (tundra) in the Arctic

  ->Shift of boreal forests to the north (as tundra thaws)

  -> Tropical rainforests (currently at carbon capacity) may reduce their storage
• Ocean carbon sinks:

  • Increased store in sea grasses and algae, but overall reduction as sink because:
  • Tropical oceans have decreased carbon dioxide solubility as they are becoming warmer so absorb less 
  • Decreased efficiency and slowing down of the biological pump
• Human Factors

  • The IPCC has identified key factors driving anthropogenic greenhouse gas emissions

  
• • The top five countries that emit carbon dioxide are China, the USA, India, Japan and Russia
  • China overtook the USA as a result of rapid urbanisation and industrialisation which indicates a positive relationship between economic growth and carbon emissions