‘Weather’ is what happened today or yesterday, or this year, or since the baby was born. ‘Climate’ is what you understand about a place when you have lived in it for 30 years or longer. If the place was Adelaide, you may remember hot summer days occasionally reaching 40°C, frosty winter mornings and cold school rooms, but mostly an equable, so-called Mediterranean climate. If you lived in Scotland perhaps you recall freezing winters with a metre of snow, chilly springs with gusts of rain and so on. The weather varies very widely wherever you are, but the climate, well, it really stays the same over half a lifetime – or at least it used to, because climate is the average of all the weather’s variations.

During most of the first decade of the 21st century, southern and western Australia experienced severe drought. Explosive bushfires in the summer of 2008–9, the drying of the Murray and the Darling rivers, unheralded water restrictions; to those younger than age 60 these seemed to be a remarkable change from the normal climate. But there were enormous fires in Victoria in 1939, there were devastating droughts at the end of the 19th century and before the construction of dams and weirs the Murray would shrink during drought to a series of pools (see Figure 3.1). Droughts (and flooding rains) are just part of the Australian climate. Particularly long droughts, those lasting for up to 10 years, occurred in the periods 1898–1905, 1911–16, 1939–45, 1958–68 and 1991–96.