J. Geophys. Res. Atmos. http://doi.org/bgd8 (2016)

Credit: © IKON IMAGES / ALAMY STOCK PHOTO

The difference between daily maximum and minimum temperatures — the diurnal temperature range — is one measure of changes in daily temperature distributions. However, in the IPCC Fifth Assessment Report, it was noted that we only have medium confidence in such changes, with observational uncertainties reducing confidence.

To address this issue, Peter Thorne of Maynooth University, Ireland and co-authors investigate changes in the diurnal temperature range over the past century using seven independently derived datasets. Multiple datasets were compared as they have differences in collection and analysis, such as the resolution of interpolation and the reporting of absolute values or anomalies. The authors look at the global average, and at some regions such as North America, Europe and Australia to determine the limitations of the datasets.

The authors show that there is consensus across the datasets for a significant decrease in the global-mean diurnal temperature range from 1950 to 1980. After this, there is disagreement between the datasets, with some showing increasing, while others show decreasing trends — and so no significant trend is detected. This disagreement is also seen before 1950, and is attributed to data paucity, which could be remedied through data recovery.