 Now we're talking about shorter-term changes in climate on human timescales and Lake George is famous for the way the water level rises for a number of years and then falls and sometimes disappears completely. In 2015 the lake was completely dry. In 2016 after a wet year the water came up quite close to the road again but it didn't come nearly as high as it had done in parts of the 1980s and particularly in the 1950s and the 1960s. The 1950s and through to the mid-1960s was a period of above-average rainfall right across south-eastern Australia and the lake was full enough. It was up to nearly five metres deep, four and a half metres deep at its maximum point so it's not a very deep lake. But in the 50s and 60s it lapped up against the highway. Sometimes it even flooded the highway in those days. And when I came to Canberra in 1963 I learned to water ski on Lake George when I was a boy. My parents had a boat and there were often quite a lot of power boats out here as well as yachts and people going fishing. There were fish in the lake and it seemed like it was a permanent lake and it was a focal point for picnics and for family outings and all the rest of it. So from the mid-1960s there was a period of dry years and the lake started to drop and there have been periods since when it was completely empty. So the variations can be almost annual but you can have decade or periods where the lake is either relatively empty of water because it's dry or as of the case in the 50s and 60s you see a real lake.