Effects on the Biosphere (DP IB Geography): Revision Note

Ecosystems and biomes play a key role in carbon cycling

The availability of moisture for plant and animal distribution and growth is important

Changes in temperature, rainfall, and habitats affect species' survival, migration patterns, and interactions

This results in changes to ecosystem functions and services

Some places will improve conditions for crops and ecosystems, while others will suffer

Biomes may move north or south because they need specific climate conditions:

• Polar and tundra biomes are at risk because they cannot move any further north or south

• Rising sea temperatures and ocean acidification have caused coral bleaching

As biomes move, migration and behaviour patterns also change

• Animals will have to migrate longer distances to find cooler climates, reduced pests, diseases and predators so they can breed 

• Fish species are already moving further north and south of their usual habitats 

• Reduced hibernation time due to warmer winters

• Migrations begin earlier every year, with the birds leaving their winter nesting sites and heading north for the summer

Soil erosion reduces the fertility of the remaining soil

Soil erosion increases when rainfall is higher and vegetation is low

Warmer temperatures and increased rainfall increase soil loss on slopes

Increased rates of drought slow plant growth, reduce carbon cycling and reduce nutrient transfer to the soil; lack of nutrients and water exposes soil erosion; soil erosion can lead to desertification

Agricultural practices expose soil to increased run-off and erosion

• Overgrazing: grazing animals destroy vegetation that binds soil particles

• Over-cultivation: soil becomes exhausted

• Deforestation: loss of roots to bind the soil 

Suitable areas for agriculture will change

• Farmers may have to change their crops 

• Areas that could grow certain crops will have to change

  • Wheat grown in the USA will have to be grown in Canada

  • This will affect the USA's economy while boosting Canada's

Coastal flooding may lead to salt intrusion

Water shortages affect irrigation, limiting the choice of crops that can be grown

Food shortages will lead to malnutrition and famine

• A rise of 3°C would reduce crop yields by 35% across Africa and the Middle East

• A 2°C rise would cause 200 million people globally to experience hunger