Climate Change
Geography: Edexcel A Level, topic 8.4.3
Climate Change
Climate change is causing changes in climate zones across the world, particularly with the increase in areas suffering from drought.
Human causes
- Human causes of climate change include the enhanced greenhouse effect.
- The enhanced greenhouse effect causes an increase in global temperature.
- Greenhouse gas emissions increase because of the burning of fossil fuels and carbon stores are reduced because of human activity, such as deforestation and urbanisation.
Change in climate belts
- Change in temperature impacts the air circulation system.
- The current system sees low pressure and high rainfall at the equator with high pressure and low rainfall at the poles and at 30oN and 30oS.
- A change in temperature may cause these systems to shift into a different position, leading to rainfall patterns changing.
- With a 2oC increase in temperature, 5% of the world’s climate zones have changed. A further 2oC increase would see a further 10% shift in climate zones.
Frequency of droughts
- Because of the shift in climate zones, the areas which are cold are decreasing and the areas which are dry are increasing.
- The arid and semi-arid areas are likely to expand further within continents such as Sub-Saharan Africa.
- Europe and Western Asia are seeing the highest threat from the risk of drought.
Amazonian Drought Events
If the changes in drought events that we are currently seeing continue, there are concerns that the Amazon will stop being a carbon sink and be a carbon source instead.
Drought
- Drought causes trees to die and plant growth rates decline, resulting in the forests losing their ability to be a carbon sink during a drought.
- As a result of dried dead organic matter, forest fires can break out quickly, releasing the CO2 back to the atmosphere.
Amazon droughts
- In 2005 and 2010, the Amazon suffered droughts. But the drought of 2014/15 was the worst drought in Brazil in 80 years.
- The rainforests and other vegetation found within the Amazon basin holds 17% of the world’s terrestrial vegetation carbon.
Test yourself on Climate Change
What percentage of the world's climate zones have already changed with a 2oC increase in temperature?
What percentage of the world's terrestrial carbon is held in the Amazon basin?