A recent popular visualisation of global temperature changes since 1850 was created by Ed Hawkins, a climate scientist from the University of Reading in the UK. What would the data for Australia look like? A visualisation with the same date range is not possible as Australian climate records do not exist with an reliability before 1910.
For this work the following was used:
- the Bureau of Meteorology (BOM) ACORN-SAT data is validated data from over 60 Australian weather stations and is used for long term climate modelling. 62 of the stations have data extending from 1910 to the present date. Many more start at a later date. The data is updated annually and finishes in December 2015. Data for Jan to Mar of 2016 was added from the BOM monthly average data for the 62 individual stations, although some only have partial data sets.
- the monthly average maximum temperature was averaged across all stations for each month.
- each average was compared to the monthly average for the period 1950 to 1980 and expressed as a variation – this period being selected as a baseline as it is a frequently used reference date range. Temperature rise prior to this period since pre-industrial times would add approximately 0.25 degrees C to the indicated values.
- as there are only 62 data points, the month to month variation is quite high so an exponential smoothing function was applied. This does not affect the overall trend, only the individual monthly values.