The causes of climate change give us an insight into what we must do - the economic, environmental and social impacts tell us what we risk if we don''t act.

At A Glance.....




Most of the Earth's energy comes from the sun. Some of the sun's energy that hits the Earth's atmosphere is reflected back into space. The sun's energy that remains within the atmosphere is trapped by greenhouse gases (such as carbon dioxide). These warm the Earth, making it livable. This is called the greenhouse effect.

The problem occurs when concentrations of greenhouse gases keep increasing, due to the use of fossil fuels, trapping too much heat within the Earth's atmosphere.

Greenhouse Gases

RainAbout three-quarters of the natural greenhouse effect is due to water vapour. The next most significant greenhouse gas is carbon dioxide. Methane, nitrous oxide, ozone in the lower atmosphere, and CFCs are also greenhouse gases.

The concentration of carbon dioxide is approximately 30 per cent greater than it was in the 18th century, before the industrial revolution. It has increased from around 280 parts per million (ppm) to approximately 379 ppm (2005). Methane levels have risen from a pre-industrial concentration of about 700 parts per billion (ppb) to 1700 ppb with concentrations of CO2 equivalent currently at 455ppm (2005). This will have an effect on the world's climate.

Most of the increase in carbon dioxide comes from burning of fossil fuels such as oil, coal and natural gas for energy, and from deforestation.


DroughtThe earth's temperature has already risen 0.74 of a degree (2005). A temperature rise higher than 2 degrees Celsius is predicted to result in catastrophic and irreversible damage. In Australia, climate change impacts include:

  • more severe and more frequent droughts
  • more severe and more frequent bushfires
  • a decrease in water availability
  • loss of snow cover
  • bleaching of the Great Barrier Reef
  • loss of many plant and animal species

Globally, the impacts of climate change include:

  • the breakdown of globally important ice sheets that could lead to very large and irreversible sea level rises over the long term
  • changes in ocean circulation systems that are important for moving rain, air and marine life
  • much more extreme climate conditions, like severe storms, winds, floods and droughts around the world irreversible damage to important and vulnerable ecosystems such as coral reefs, alpine areas and rainforests.


Global warmingThe scientific evidence of climate change is overwhelming - no longer prediction but actual events show us this. How do the scientists assess the world's climate and verify the changes?

In 1988, the United Nations Environment Programme and the World Meteorological Organization set up the Intergovernmental Panel on Climate Change (IPCC) to examine the most current scientific information on global warming and climate change. More than 2,500 of the world's leading climate scientists, economists, and risk experts contributed to the panel's report, Climate Change 2001: The Third Assessment Report.

The most recent report from the IPCC is the 'IPCC Fourth Assessment report (AR4)' which was released in 2007.

Further information

Australian Greenhouse Office

Greenhouse Effect and Climate Change Bureau of Meteorology

Intergovernmental Panel on Climate Change


ScepticsThe international scientific consensus on climate change caused by human activities is overwhelming. A recent paper in Science examined every single peer reviewed scientific journal article from 1993 to 2003 that contained the phrase "global climate change". Of the 928 articles that used the phrase, not a single one disagreed with the consensus view that current climate change is caused by human activity.

However, some right-wing think tanks, fossil fuel companies and a few lone scientists deny that it exists or deny that its impacts will be problematic. Click here for a review of skeptic's arguments.

In early 2010 Lord Monckton visted Australia with some alarming claims.  Click here to read a debunk from Mike Carelton of the Sydney Morning Herald.  Also see Clive Hamilton's expose of the climate change denial movement.

Update on global warming 'contrarians' from the Union of Concerned Scientists.

William Kininmonth - Ten years ago, William Kininmonth was a senior administrator at the Bureau of Meteorology. His book Climate Change: A Natural Hazard was recently launched by the industry lobby group Lavoisier Group (see below).

Ian Castles former head of the Australian Department of Finance and a former Statistician.

Ian Plimer Professor of Geology at the School of Earth Sciences at the University of Melbourne. He sits as Director on the boards of several mining companies.

The Lavoisier Group

The Lavoisier Group distributes the work of geologist Bob Carter, Ian Castles, William Kininmonth, Ian Plimer and a few other Australian sceptics.

The Institute of Public Affairs

The Institute of Public Affairs is financially backed by a business lobby, receives funding from Exxon Mobil and is Chaired by former Victorian Treasurer Alan Stockdale. Promotes 'free market ideology' and seeks to put an end to the influence of NGOs such as Oxfam and the World Wide Fund for Nature (WWF). Prior to taking up the role of Executuve Director of the IPA, John Roskam worked for the Howard and Kennett Governments and was Manager of Government and Corporate Affairs for Rio Tinto.

Toxic Sceptics