What causes climate change?

There is now strong evidence, and almost unanimous agreement, that significant climate change is occurring. It is also likely that most of the recent warming can be attributed to human activities. A survey published in 2013 looked at over 12,000 peer-reviewed climate science papers, and found that there was a 97% consensus among papers taking a position on the cause of global warming in the peer-reviewed literature that humans are responsible.

Natural Causes

Some changes to the earth's climate are caused by the interactions between the sun, land, oceans and the atmosphere. These occur over very long periods of time.

Human Causes

Human activity has changed the concentration of greenhouse gases in the atmosphere in two important ways:

  • We have cut down forests to develop land for agriculture. Trees absorb carbon dioxide so, with fewer trees, more carbon dioxide builds up in the atmosphere. Also, the agriculture that replaces the forests can often be a source of emissions.
  • By burning fossil fuels like coal, oil and gas for energy, we release greenhouse gases.

Since the start of the Industrial Revolution in the 18th century concentrations of greenhouse gases have increased by 30 per cent.