The Geography and Map Division is excited to share the publication of our latest interactive map, showcasing the Climatological Database for the World’s Oceans (CLIWOC), a fascinating database of digitized European ship logbook entries from 1750 to 1850. Our visualization lets you explore this data by ship nationality and provides voyage and weather details for individual logbook entries. The database, digitally acquired by the Library of Congress and available for download, provides a global view of colonial maritime expansion and detailed climatological recordings for this period of history.
CLIWOC was a 2001-2003 European Union-funded research project involving a large international team of researchers and organizations compiling and digitizing data from over 280,000 logbooks written aboard European sailing ships between 1750 and 1850. As was already common practice, sailors in this time period would systematically record daily weather observations, especially wind conditions, primarily for the purposes of calculating their geographic position on the open ocean. From the details of individual logbook entries to the extensive collection of European logbooks analyzed for the project, the resulting database is an invaluable resource for the study of climate and maritime history at many scales.
The CLIWOC database was originally published in Microsoft Access format. In 2018, after seeing a presentation of CLIWOC data by Georgetown University environmental history professor Dagomar Degroot, programmer Steven Ottens worked to reformat the database into more manageable OpenOffice spreadsheet, tab-delimited text file, and Geopackage formats. The database in these formats was then hosted on Degroot’s HistoricalClimatology.com website. Later in 2018, with recommendation by the Geography and Map Division, the Library of Congress acquired a digital copy of the database in these formats as part of the Selected Datasets Collection, a collection managed by the Digital Content Management section with the aim of preserving and providing enduring access to important datasets in a wide range of fields.
This visualization of the CLIWOC database categorizes logbook entries by ship nationality: British, Dutch, French, and Spanish. An interactive legend allows users to isolate the map view only on select ship nationalities. Viewing ship locations by nationality across the database shows clear geographic patterns in imperial expansion and global trade. The voyages of Atlantic Slave Trade, including the Middle Passage in which millions of enslaved Africans were transported across the Atlantic to colonial possessions in the Americas, are clearly visible across the dataset.
Patterns specific to European colonial possessions are evident as well, including Spanish ships sailing to Mexico and British ships associated with the Hudson Bay Company voyaging north into present-day Canada. Geographic chokepoints faced by all mariners of the time are also noticeable, from Cape Horn at the southern tip of the Americas to the Strait of Malacca between present-day Malaysia and Indonesia.
The dataset is far more sparse in the Pacific Ocean, as CLIWOC only captures a subset of European sailing vessels and does not include the journeys of indigenous Pacific Islanders, among other groups, who have mastered maritime travel for thousands of years. Zooming in on Pacific Ocean voyages in CLIWOC, however, provides opportunities to explore the incredible level of detail in this dataset. For example, John Byron, a British Royal Navy captain, completed the first circumnavigation of the globe that was accomplished in less than 2 years (June 1764 to May 1766) at the helm of the HMS Dolphin. One of many logbook entries from this voyage can be found along the coast of Chile. This entry (screenshot below) notes the exact date of the observation, ship name, nationality, captain, origin, destination, and weather conditions. Here we see that at this point, John Byron and his crew experienced “first moderate, remainder strong gales and squally” conditions on April 17, 1765. This is just one of countless fascinating snapshots of distinct voyages to be found in the database.
As the name would suggest, the Climatological Database for the World’s Oceans is a valuable resource not only to studiers of maritime history, but to climate researchers as well. As described in the original CLIWOC report on the database, from the observations contained within thousands of logbooks, “a picture can be recreated of the climate of those times, which, coming as they did before any significant anthropogenic influence could be exerted on the climate, provide a unique opportunity to explore how the climate of the oceans behaved in ‘natural’ conditions.”
The CLIWOC interactive map offers an engaging, user-friendly view of a hundred years of European maritime travel while also providing just a glimpse of the vast possibilities for study in this rich dataset. To explore CLIWOC further, we encourage you to download the database and dive in!