Understanding Climate Change

Climate change science

Climate change is a change in the average pattern of weather over a long period of time.

There is clear evidence that our climate is changing, largely due to human activities. The Fourth Assessment Report, produced by the Intergovernmental Panel on Climate Change (IPCC) in 2007, states global warming is ‘unequivocal’ and ‘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’.

In other words, there is overwhelming evidence for human-made global warming.

The IPCC report represents the international consensus on climate change science from literature that has been extensively peer-reviewed and published in scientific journals.

There are multiple lines of evidence that show the Earth's climate system is warming. These include increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

When scientists talk about climate change they mean warming of the climate system as a whole, which includes the atmosphere, the oceans, and the cryosphere (ice, snow and frozen ground). The evidence clearly indicates that the climate system is continuing to warm, including increasing land temperatures, warming oceans and melting snow and ice.

Climate change is not just about global warming. The science indicates that the climate will be altered in many other ways. For example, there will be changes in rainfall patterns and ocean currents, changes to the intensity and frequency of extreme events such as storms, droughts and floods, rising global sea level and ocean acidification.