The UN Intergovernmental Panel on Climate Change (IPCC) has evaluated “business as usual” or “do nothing” scenarios and concluded that temperatures would be likely to reach levels where the impacts are serious. The IPCC Working Group II concluded in their 2007 report that some impacts would include
- Species loss: 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction
- Coasts: increasing risks of storm damage and coastal erosion with millions more people affected by flooding by 2080
- Coral: more frequent coral bleaching and mortality, unless thermal adaptation or acclimatisation occurs
- Water: by 2050 river runoff and water availability are projected to increase by 10-40% at high latitudes and in some wet tropical areas, and decrease by 10-30% in some dry regions at mid-latitudes and in the dry tropics
- Human health: studies in temperate areas project that climate change will bring some benefits, such as fewer deaths from cold. But, these benefits will likely be outweighed by negative health impacts particularly in developing countries.
- Food: Overall food production is projected to increase with increases in local average temperature over a range of 1-3°C, but above this range as would be expected in a “do nothing” scenario, it is projected to decrease.