What causes climate change?

There is now strong evidence and almost unanimous agreement that significant global warming is occurring. It is also likely that most of the recent warming can be attributed to human activities.

Natural Causes

Some changes to the earth's climate are caused by the effects on each other of the sun, land, oceans and 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. First, 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.

Second, by burning fossil fuels like coal, oil and gas for energy, we release greenhouse gases. Since before the industrial revolution, which began in the 18th century, concentrations of greenhouse gases have increased by 30 per cent.