The tectonic plate that Australia sits on is moving at a rate of 7cm to the north every year. This creates a discrepancy between local coordinates and global coordinates that are derived from GNSS. To address this the Geocentric Datum of Australia will be adjusted on 1 January 2017 by 1.8 meters to the north. This will bring local and global coordinates aligned in 2020.
As Joseph Kerski raises in his article, this “is a nice reminder that physical geography matters.” He reminds us to “know the sources of your data, including the datum itself.” An important reminder.