Biases in the Australian High Quality Temperature Network

Various reports identify global warming over the last century as around 0.7°C, but warming in Australia at around 0.9°C, suggesting Australia may be warming faster than the rest of the world. This study evaluates potential biases in the High Quality Network (HQN) compiled from 100 rural surface temperature series from 1910 due to: (1) homogeneity adjustments used to correct for changes in location and instrumentation, and (2) the discrimination of urban and rural sites. The approach was to compare the HQN with a new network compiled from raw data using the minimal adjustments necessary to produce contiguous series, called the Minimal Adjustment Network (MAN). The average temperature trend of the MAN stations was 31% lower than the HQN, and by a number of measures, the trend of the Australian MAN is consistent with the global trend. This suggests that biases from these sources have exaggerated apparent Australian warming. Additional problems with the HQN include failure of homogenization procedures to properly identify errors, individual sites adjusted more than the magnitude of putative warming last century, and some sites of such poor quality they should not be used, especially under a “High Quality†banner.