>>11366238They were homogenised to produce consistent data
If you have thousands of different weather stations that take temperature at different times of day with different equipment in different conditions of shade/direct sunlight you cant get a clear picture of climate
By standardising the reading of temperature across australia which is what they did they can get rid of anomaly's that cock up the data
Also they didnt delete or lose the data, its still available on the meteorology website:
>"While the national analysis of temperature begins in 1910, the Bureau of Meteorology also holds temperature data from earlier periods.">"Working with this early data is challenging, due to the relative sparseness of temperature records across the country, and the large range of unstandardised instrumentation and observing practices." 
