Changing Ecosystems (AQA A Level Geography): Revision Note

Climate Change & Ecosystems

• On a global scale, changes to the climate – especially rapid change – have the potential to cause ecological collapse, especially when species cannot adapt at the same rate of climate change

• The overall effect can be described in three ways:

  • Species die out, allowing other species to dominate (either through inward movement or natural order of existing species)

  • Species respond through adaptation if given time

  • Species move to other areas with more suitable conditions

• Changes include:

  • Temperature rise – affects the distribution of species, particularly those sensitive to temperatures (coral reef, polar bears, etc.), leading to changes in ecosystem composition and species death

    • The IPCC estimates that a rise of 1.6°C will affect 20-30% of all plant and animal life at risk of extinction

  • Extreme weather – floods and droughts – are expected to increase, which could kill species unable to adapt to wetter or drier climates 

    • In the UK, beech woodland is at risk from summer droughts and changes in migratory bird paths

  • Sea level rise - (melting ice and thermal expansion of oceans) puts coastal ecosystems at risk of being permanently lost and saltwater intrusion into freshwater systems endangers species found within or force them to move further inland

    • Salt marshes along the coast of the UK are at risk of being submerged permanently through rising sea levels, endangering breeding patterns of birds and other animals reliant of this ecosystem

Climate Change Impacts on Europe

Mediterranean Region

• Temp. rise is more than European average

• Decrease in annual precipitation

• Increased desertification

• Increased water demand

• Higher mortality rates and risks of forest fires

Arctic Region

• Temp. rise is more than global average

• Decrease in sea ice cover

• Decrease in permafrost

• Intensified shipping and exploitation of oil and gas

• Increased loss of biodiversity and Greenland ice sheet

Coastal and Regional Seas

• Increase in sea surface temps

• Increase in winter precipitation

• Increase ocean acidification

• Expansion of fish and plankton species northwards

• Decreased fish stock

Mountainous Regions

• Temp. rise is more than European average

• Glacial volume and extent decreases

• Decrease in mountain permafrost

• Upward shift of plant and animal species

• Increase risk of soil erosion and loss of tourism

Northern Europe

• Temp. rise is more than global average

• Snow, lake and river ice decreases

• Increased river flows

• Increase in hydropower potential

• Increased summer tourism and damage from winter storms

Central and Eastern Europe

• Warm temp.  extremes increase

• Decrease in summer precipitation

• Increased rise in water temps

• Increase risk of forest fires

• Decrease in economic value of forests

North-western Europe

• Increase rise in temps above European average

• Increase in winter precipitation

• Increased river and coastal flooding

• Decrease in energy demand for heating

• Increased demand for energy for cooling

Human Exploitation of Ecosystems

• Human exploitation of ecosystems has changed them over time

• Deforestation has had the biggest impact globally, with over 50% of all mature forests lost to logging

• Tropical rainforests are threatened the most with loss of biodiversity through deforestation

• Coastal ecosystems have been damaged through pollution, oil spills and waste (raw sewage and plastics in particular)

• Other anthropogenic examples include:

  • Urban planning – building developments separate natural ecosystems and split populations

  • Leisure and recreation – diving on coral reef systems disturbs feeding and breeding grounds; touching corals kills the polyps

  • Marine resources – overfishing has depleted fish stocks to the point of collapse; dredging for sand destroys coastal ecosystems and increases risk of coastal erosion and flooding

  • Resource use – many species die out through clearance of ground for resources as habitats are destroyed, along with feeding and breeding grounds

  • Flooding and erosion – management strategies can interfere with natural succession or affect downstream/coastal ecosystems by starving them of nutrients that would normally be transported to the area, thereby preventing species from growing there