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Climate change
- Global temperatures have consistantly
fluctuated from cooler phases and glacial
periods to warmer periods where these
glaciers have retreated
- In recent years the warming stage has been
accelerated: termed global warming
- In recent years the warming stage has been
accelerated: termed global warming
- Feedback mechanisms
- Negative feedback: Restoration by nature back to its previous
state eg Deforestation: given time trees will grow back
- Positive feedback: things are not restored to back
to a previous state and things begin to get worse
- Examples
- Melting permafrost: peat deposits decompose anaerobically
at a quicker rate. This releases methane in large quantities
and speeds up global warming
- Changing albedo: snow/ice holds a high albedo. As this melts dark
soils and oceans reveled which have lower reflective ability and
therefore absorb more heat
- Rainforests: less rainfall occurs in equatorial regions and
so vegetation begins to dry. This increases the risk of
burning and subsequent emission of gases.
- "Switching off" of the Gulf Stream that keeps Europe warm
- Melting permafrost: peat deposits decompose anaerobically
at a quicker rate. This releases methane in large quantities
and speeds up global warming
- Negative feedback: Restoration by nature back to its previous
state eg Deforestation: given time trees will grow back
- Evidence for climate change over the past 20,000 years (proxy (secondary) sources)
- Tree ring dating: tree rings increase as they get older. The patterns of their growth are
used to produce timescales which provide information on previous climates.
- Ice core analysis: Different levels of CO2 are trapped in the ice dependent on
the climatic temerature
- Sea level change
- Shift in vegetation belts: location of certain types of vegetation is dependant on the current climate
- Tree ring dating: tree rings increase as they get older. The patterns of their growth are
used to produce timescales which provide information on previous climates.
- Causes of global warming
- Increased production of CO2 and other greenhouse gases (primarily
human induced). Caused by the burning of fossil fuels, land clearing
and agriculture which traps heat radiation and increases the
greenhouse effect, causing the Earth's temerature to increase.
- Fossil fuels have been burnt more readily within
industry and transport
- Leads to:
- Increase in sea level temerature due thermal expansion
- Glacial retreats
- Increased extreme weather events
- Increased acidity of oceans
- Reduction in crop yields due to the burning of land and
inhospitable temperatures, resulting in greater food
shortages and disease.
- Increase in sea level temerature due thermal expansion
- Fossil fuels have been burnt more readily within
industry and transport
- Additional CO2 within our atmosphere comes mainly from the burning of fossil fuels,
according to IPCC. This is due ti the isotopic signature of CO2 that has been produced since
the Industrial Revoultion
- Increased production of CO2 and other greenhouse gases (primarily
human induced). Caused by the burning of fossil fuels, land clearing
and agriculture which traps heat radiation and increases the
greenhouse effect, causing the Earth's temerature to increase.
- Response to global warming
- International responses: coutries need to
co-operate if we are to succeed in reducing the
effects of global warming
- Kyoto Agreement and protocol (1997): Limits placed on reduction in
greenhouse gas emissions, many countries have pledged to
reduce CO2 emissions by 20%, however many countries are not
on course to reach these targets due to a rise of the energy sector
- Carbon credits: a scheme that allows amounts of CO2 usage according
to their need and have been implemented to reduce global warming.
Credits can be exchanged businesses, or bought and sold.
- Agenda 21: a voluntary action plan implemented by the UN to improve
sustainable development. First introduced at the Rio summit in 1992.
- Kyoto Agreement and protocol (1997): Limits placed on reduction in
greenhouse gas emissions, many countries have pledged to
reduce CO2 emissions by 20%, however many countries are not
on course to reach these targets due to a rise of the energy sector
- Small scale, local responses:
- Congestion charges ie London
- Catalytic converters
- Increased availability of public transport
- Clean air act of London 1956: Raised height of chimneys, smoke
free zones, and a shift to natural gas and electricity instead of the
burning of coal within industry
- Double glazing and insolation
- Double glazing and insolation
- Number plate regulations
- Deforestation reduction policies
- Renewable energy investment
- Awareness and education eg recycling
- Congestion charges ie London
- International responses: coutries need to
co-operate if we are to succeed in reducing the
effects of global warming
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