6.7A Impact of Increasing Demand for Food and fuel

• Growing Resource Demands:

  • The biosphere sequesters about one quarter of fossil fuel carbon emissions every year, slowing down the rate of global warming
  • However, the biosphere’s capacity to sequester carbon dioxide is being reduced due to land conversion 
  • Land conversion is being driven by an increasing demand for food, fuel and other resources
• Deforestation:

  • Forests cover 30% of the Earth’s land area and absorb rainfall and increase groundwater storage
  • Deforestation occurs for either the timber or the space they occupy and is driven by the increasing demand for commodity production
  • An estimated 10 million hectares are deforested every year
• Deforestation has impacts on the water cycle:

  • Reduced interception by vegetation so infiltration to soil and groundwater changes
  • Increased erosion and surface run-off, increasing sediment eroded and transported into rivers
• Deforestation has impacts on the carbon cycle:

  • Reduced storage in soil and biomass
  • Reduced carbon dioxide intake during photosynthesis
  • Increased carbon influx to atmosphere by burning and decomposing vegetation
• Afforestation:

  • Afforestation and reforestation are beneficial for carbon dioxide sequestration but can be controversial in its impacts:
  • Commercial trees such as palm oil often store less carbon, use more water and are prone to disease
• Grassland Conversion:

  • There are two main types of grassland which cover 26% of the Earth’s land area
  • Temperate grassland - no trees and a seasonal growth pattern linked to a large annual temperature range e.g. North America
  • Tropical grassland or Savannahscattered trees with a wet and dry season e.g. Africa’s serengeti
• Grassland conversion:

  ->When grasslands are used too intensively for animals or agriculture it disrupts the carbon and water cycles

  • Rapid increase in population and changes from nomadic to sedentary farming along with the impacts of climate change and poor land management 
  • Soil and ecosystem degradation is now becoming a worldwide issue which is leading to a loss in carbon storage