6.12 - Effects of Global Warming

Biological consequences of global warming

• The rise in temperature is driven by rising carbon dioxide, mainly from the combustion of fossil fuels and from deforestation.
• Global warming then has several biological consequences: changes in distribution of organisms, rising sea levels, more extreme weather, and falling biodiversity.

Changes in the distribution of organisms

• As temperatures and rainfall patterns change, organisms shift where they can live:
  • Organisms that need warmer conditions spread into new areas
  • Organisms that need cooler conditions occupy smaller ranges
  • Some species migrate towards the poles
• Some organisms shift to new regions, but others cannot move or adapt quickly enough, so their ranges shrink and some are lost.
• Evidence for these shifts in distribution links the environmental change to its effect on living things.

Rising sea levels and extreme weather

• Higher temperatures make seawater expand and the ice caps melt, so sea levels rise.
• This increases flooding in low-lying coastal areas and the loss of habitats.
• Extreme weather events - Droughts, storms, and floods - become more frequent and more severe.
• Habitats are lost as a result - for example, wetlands dry out or are submerged.

Falling biodiversity

• Together these changes reduce the variety of organisms an area can support, so biodiversity is likely to fall.
• This is because some species cannot adapt or migrate quickly enough and may become extinct.