Greenhouse effect

The greenhouse effect is a natural process that warms the Earth's surface. When the Sun's energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs).The absorbed energy warms the atmosphere and the surface of the Earth. This process maintains the Earth's temperature at around 33 degrees Celsius warmer than it would otherwise be, allowing life on Earth to exist.



Department of the Environment 

Climate change

Human activities—such as burning fossil fuels or clearing forested land for agriculture and housing—are increasing the levels of greenhouse gases, particularly carbon dioxide.

This is the enhanced greenhouse effect, which is contributing to warming of the Earth.

The average air temperature of earth has increased by around 0.85 degrees Celsius since 1880. In Australia, average air temperatures have increased by around 0.9 degrees Celsius since 1910, and each decade has been warmer than the previous decade since the 1950s. 

Rainfall patterns have also changed. South-west Western Australia has experienced long-term reductions in rainfall during the winter half of the year. Rainfall in this region has already reduced by around 15 per cent since the mid-1970s. (Department of the Environment)

Pseudo scorpion pic by Michael Curran
Pseudo scorpion - Photo © M Curran

Carbon dioxide and forests

  • During photosynthesis, plants absorb carbon dioxide, water, and energy from the sun to produce sugars and other compounds.
  • During this process, carbon is stored or 'fixed' in the stems, leaves and branches of the plant, and oxygen is released into the air. Half of the dry weight of woody plants is carbon.
  • Some carbon dioxide is released into the atmosphere by the plant (in the process of 'respiration') and when the plant is burnt or decomposes.

Climate change and the management of our forests

In south-western Western Australia, the impact of climate change is most apparent in a substantial drying trend, with significant decreases in rainfall, streamflow and groundwater levels since the mid-1970s in the last 40 years.

In the northern jarrah forest there has been a 15 per cent reduction in rainfall since the mid-1970s, resulting in some tree deaths, and negatively affecting water dependent ecosystems throughout the forest.

The Department, in recognition of the possible impacts of climate change on native forest ecosystems and processes, will manage our State forest and timber reserves to support and promote mitigation of climate change, and the adaptation of forest ecosystems and their elements to climate-related changes, consistent with the principles of ecologically sustainable forest management.