Do you think a Captain making entries in his ship logbook in the 19th century could possibly have imagined that 150 years in the future, scientists would be using that data to reconstruct climate records?

That’s exactly what’s happening as part of the GloSAT project. Marine air and sea temperatures recorded in ships’ logbooks as well as other observations are being digitised and used to evaluate the temperatures produced by climate models. However, it’s not quite as simple as just copying the measurements from a logbook into a digital format. It’s important to know what instruments were used and how those measurements were made in order to be able to compare and calibrate them with existing data.

Page from the log of HMS Tourmaline from 1895 listing instruments carried on board. From the UK National Archives, Kew. Image courtesy Clive Wilkinson

Clive Wilkinson, a member of the GloSAT team, has been investigating and has collected an array of observing instructions and examples of observing methodologies, as well as examples of instrument type and exposure from various data rescue projects. These data rescue projects, representing several nationalities, have taken place over the last two decades. Although visiting archives has not been possible in the past few months, archives and colleagues in Norway, Finland, Argentina, Chile and the United States have been contacted and are all enthusiastic about contributing to the work.

Cover of a register of thermometers issued to Royal Navy ships between about 1855 and 1900. From the UK National Archives, Kew. Image courtesy Clive Wilkinson