Physical factors of climate change
- Changing output of solar radiation
- Volcanic eruptions
- Wobble roll and stretch theory
- Changing oceanic circulation and land masses
Human factors of climate change
- Increased consumption of fossil fuels
- Increased output of methane, nitrous oxides and CFC's
Changing output of solar radiation
When sunspot activity is greatest the global mean temperature seems to rise
After violent eruptions, enourmous amounts of volcanic dust particles, are ejected high into the atmosphere. After being blown all over the atmosphere by global winds these particles shield the sun's rays and therefore reduce the temperatures
Wobble, roll and stretch theory
- The earth wobbles in space like a spinning top. As a result there is a variation in the time of year when the earth is nearest the sun.
- Every 41000 years, there is a change in the tilt of the earth's axis. A greater tilt or "roll" means more sunlight for polar regions.
- Over a 97000 year cycle, the earth's orbit "stretches" affecting the amount of energy received
- These changes affect the amount of insolation reaching the earth
Changing oceanic circulation and land masses
- Varying oceanic circulation causes certain areas to cool down and warm up depending on how the current changes.
- If land changes over time, current can alter.
Increased consumption of fossil fuels
- Since the industrial revolution, we have been burning a lot of carbon based fuels e.g. Coal, oil and natural gas.
- All this burning has resulted in an increase in global CO2 levels.
- Apparently combustion is responsible for 55% of greenhouse gas emissions.
- Once in the atmosphere, it remains there for a long time.
The clearance and burning of tropical rain forests increase the level of co2 in the atmosphere because trees- once they are cut down- cannot recycle the CO2 through photosynthesis.
Increased output of methane, nitrous oxides and CFC's
- These gases are a lot more harmful than CO2.
- Methane has been increased by, rice production, increasing number of cattle, and waste disposal sites which leak methane
- Nitrous oxides by car exhausts, fertilisers and deforestation
- CFC's are 177000 times more powerful than CO2. They do not exist naturally and are now banned.