Some environmental changes can be easily seen (eg droughts and bushfires). However, many are less evident as they occur over a long time (climate change); in remote areas (eg feral camels); under the ground (eg historic pollution); in the sea (eg ocean acidification); and in the atmosphere (eg ozone-layer depletion).
The large and complex natural systems in which these changes take place make them even more challenging to observe and understand. Such systems include the climate, cycles of carbon, water and nitrogen, and ecosystems.
For these reasons, many countries are undertaking systematic studies of environmental conditions to help them make informed decisions in response to environmental changes and associated impacts.
One broadly used method to provide a consolidated perspective on environmental change is a periodic state of the environment report (SOER). International bodies such as the Organisation for Economic Cooperation and Development (OECD) encourages its member countries to each produce a regular SOER. To assist with this, the OECD has developed a range of methods, and it also carries out its own formal reviews of member countries. The first OECD environmental performance review for Australia was published in 1998, the second in 2007 and the next is due for release in 2019.
State of the environment reports provide information about changes and trends in environmental conditions in the same way as economic indicators are used to report on the state of the economy.
Every 5 years, the EPA undertakes a review of the condition of SA's environment. The aim is to inform the SA Government and all South Australians of the current state of the environment and long-term environmental trends, and to highlight issues that can potentially prevent us achieving our environmental goals.