Climate change and climate variability are two different things.
Climate variability means natural alterations in the earth’s climate1, or the shorter term (daily, seasonal, year-to-year) variations in weather. Australia has a highly variable climate, which includes cycles of wet and dry periods, and droughts. El Niño (dry) or La Niña (wet) events are part of climate variability.
Climate change means the long-term changes in average weather patterns, such as the rise in global average air temperatures. It involves a persistent series of unusual or irregular weather events, rather than simply one or two unusual weather events. The World Meteorological Organisation describes it as when events that used to be rare occur more frequently, or vice-versa (e.g. duration and thickness of seasonal lake ice decreasing with time)2.
In Australia, the situation is made more complex by the fact that our climate is already extremely variable. The current low rainfall and reduced runoff being experienced in southeast Australia are partly caused by natural variability, as well as human-induced climate change. According to the CSIRO the relative contribution of each of these mechanisms remains uncertain3.
The CSIRO is involved in researching Australia’s climate and how it changes and varies. For more information visit its climate website or download its free publication Climate Change: Science and Solutions for Australia.