The following are the key findings of the report.
OBSERVED CHANGES:
Warming of the climate system is "unequivocal"
Eleven of the last 12 years (1995 to 2006) rank among the 12 warmest years since 1850
Global temperatures have increased 0.74 degrees since 1906
The pace of sea level rises has increased from 1.8mm per year in 1961 to 3mm per year from 1993 to 2005
Since 1978 Arctic ice has shrunk by 2.7 per cent per decade
CAUSES OF CHANGE:
There is a very high confidence that the net effect of human activities since 1750 has been one of warming
Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in greenhouse gas concentrations from human activities
Global total annual greenhouse gas emissions from human activities have risen by 70 per cent since 1970. Concentrations of carbon dioxide, the main greenhouse gas, far exceed the natural range over the last 650,000 years
CLIMATE CHANGE IMPACTS:
Temperatures are likely to rise by between 1.1 and 6.4 degrees and sea levels by between 18 cms and 59 cms (seven and 23 inches) this century
Human induced global warming could lead to impacts that are "abrupt or irreversible"
There is high confidence
that by mid-century "many semi-arid areas, for example the Mediterranean basin and the western US, will suffer a decrease in water resources.
Almost a third of plant and animal species will be at increased risk of extinction if global temperatures increase by 1.5-2.5 degrees from late 20th century levels
If temperature increases exceed 3.5 degrees between 40-70 per cent of species might be at increased risk of extinction
Increases in sea surface temperatures of 1-3 degrees are projected to result in frequent coral bleaching effects and widespread mortality
ADAPTING AND MITIGATING CLIMATE CHANGE:
More extensive adaptation measures, such as the building of storm barriers, are needed to reduce vulnerability, but there are limits and costs to what is possible
A variety of policies and instruments are available to mitigate climate change. Some examples include: taxes on carbon or reductions in existing subsidies; mandatory fuel economy limits in transport; building codes; and using tradeable permits for industry
Changes in lifestyle and behaviour can contribute to climate change mitigation.
Emission of greenhouse gases would have to peak by 2015 to limit global temperatures rises to 2-2.4 degrees over pre-industrial times.
The cost to global economic growth of fighting climate change will cost less than 0.12 per cent global gross domestic product. In the mostly costly scenario assessed, that means a loss of GDP by 2030 of less than 3 per cent.
THE LONG-TERM PERSPECTIVE:
There is high confidence that neither adaptation nor mitigation alone can avoid all climate change impacts. For example, sea level rise under warming is inevitable
Impacts of climate change are very likely to impose net annual costs, which will increase over time as global temperatures increase
Unmitigated climate change would, in the long-term, be likely to exceed the capacity of natural, managed and human systems to adapt