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Crowdsourced Science Pulls Off a Daring WWII Data Rescue

A black-and-white aerial photograph of an early 20th-century U.S. naval battleship on a calm sea.

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During World War II, sailors on U.S. Navy ships documented weather and ocean conditions while sailing in the Pacific Ocean in the early 1940s. However, these records were kept classified and were not included in the data used for current climate models. Thanks to a collaborative science project, these previously confidential meteorological observations have been retrieved and digitized, filling a significant gap in wartime data with nearly 4 million records.

Prior to this project, the observations had only been seen by the individuals who recorded them, according to Praveen Teleti. Teleti, who is a climate modeler at the University of Reading in the United Kingdom, was the lead researcher on the project.

According to Teleti, having access to this collection of past weather information will enhance the precision of our climate projections. He emphasized that without accurate knowledge of past temperatures, it is difficult to accurately determine the extent of climate change.

Maritime Weather Records

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Researchers utilize climate and weather simulations to comprehend the evolution of our world’s climate in the last hundred years, predict potential changes, and identify factors that drive these alterations. These simulations rely on meteorological data gathered worldwide and their validity is contingent upon the accuracy of the data used.

Weather data can be gathered from land through weather stations, but it becomes more complex when collecting data at sea. Before satellites were introduced in the 20th century, sailors on commercial trading ships were the primary source of maritime weather information.

The information available from that time period is not very useful, according to Teleti. Commercial ships typically followed a few specific routes and rarely crossed the Pacific Ocean. The sailors who gathered meteorological data did not follow a standard procedure, resulting in potential biases. Additionally, the data was only submitted sporadically since it was collected on a voluntary basis.

The presence of environmental observations has been greatly impacted by major global conflicts like World War II.

Additionally, there was a significant decrease in the number of observations made by trading ships during World War II, particularly in the Pacific Ocean. This was due to the disappearance of the limited trade routes between the western United States and eastern Asia.

Eric Freeman, a specialist in surface marine data at NOAA National Centers for Environmental Information in Asheville, N.C., stated that the availability of environmental observations has been difficult during World War II and other global conflicts. This is due to changes in how observations are made, the loss of logbooks, and the categorization of materials.

Sepia-tinted photograph of a navy ship logbook page with black printed text.
This naval ship logbook page is from USS Farragut on the day of the attack on Pearl Harbor, 7 December 1941. It contains the ship’s name, passage to/from, date, zone, commanding officer, meteorological information, and navigation information. Credit: Teleti et al., 2023,, CC BY 4.0

But, during that time, there were also other ships sailing in the Pacific Ocean. These were U.S. naval ships sent out after the attack on the naval base in Pearl Harbor, Hawaii in December 1941. Rules of the Navy during that time required each ship to record its location and weather conditions every hour, and provided instructions for sailors on how to make these observations. However, whether or not a sailor actually followed these regulations was a different story altogether.

Retrieving Lost Data from the Past

For many years, the logbooks were kept confidential in order to safeguard classified military information. However, in 2017, the National Declassification Center made public almost 200,000 pages of WWII era documents, which included a significant number of logbooks.

Although they were available, they were not easily accessible. According to Teleti, the majority of the pages were still in paper form at the National Archives and Records Administration in Washington, D.C. In order to view the information, Teleti and his team collaborated with archivists to take photographs and scan each page.

The Old Weather-WW2 project utilized crowdsourced science to record digital versions of logbook pages. Participants were given images of the pages and instructed on how to transcribe ship identifiers, positional data, and weather observations.

The project saved a total of 3.7 million meteorological records from the time period of 1941 to 1945.

Freeman, who has assisted with other crowdsourced science projects to recover surface marine observations, said these projects can drastically reduce the time and cost to recover historic records. “As long as there is an interest by the public in the data you are trying to digitize,” he said, “citizen science is very effective, highly efficient, and typically satisfies many disciplines, providing a large breadth of public use.”

A total of 4,050 individuals volunteered to convert over 630,000 records from 28,000 logbook images of 19 ships into digital format. These records included various weather measurements such as wet and dry bulb temperature, wind speed and direction, barometric pressure, sea surface temperature, visibility, and overall weather conditions. Overall, the project successfully recovered 3.7 million meteorological observations from the years 1941 to 1945.

Ten world maps centered on the Pacific Ocean, organized in two columns and five rows. Data points in pink indicate locations where historical weather data have been logged.

The Old Weather–WW2 project has collected weather information (displayed on the left) that has contributed thousands of data points to the existing dataset (shown on the right) for the years 1941-1945. These data specifically include air pressure observations. This information was obtained from Teleti et al.’s study in 2023, which can be found at and is licensed under CC BY 4.0.

According to Teleti, the project was completed in a year and a half. He believes that the pandemic played a role in the efficient completion of the project as people were spending more time on their computers.

The quantity of weather observations in certain parts of the Pacific has significantly increased due to recent data. Teleti and his team published this information in the Geoscience Data Journal in September and will also share it at the AGU’s Annual Meeting in San Francisco in 2023.

Duo Chan, a climate scientist from the University of Southampton in the United Kingdom, who was not involved in the project, emphasized the importance of citizen science in this project. Through their involvement, citizen scientists not only accelerate the digitization of valuable historical records, but also contribute to a data set that can be used to train AI algorithms for larger-scale digitization.

Solving WWII Era Mysteries

According to Freeman, these recently obtained data greatly improve gaps in the climate data. Having more comprehensive coverage allows us to have greater trust in the accuracy of our models and our ability to replicate previous climates is strengthened.

The group anticipates that this information will not only enhance the general precision of climate reconstructions throughout World War II, but also provide insight into a notably hot period during the war.

It’s likely that they never anticipated anyone would review these observations 80 years later.

Based on historical data, it appears that sea surface temperatures were significantly higher during 1941-1945 compared to the 5 years before and after. However, the reliability of this data is much lower during the war compared to before and after. According to Chan, no climate model has been able to replicate this short-term increase in global sea surface temperature. The use of ship logs can provide insight into the climate during this time period and enhance the accuracy of climate models.

The team is also anticipating that the information could assist researchers in limiting the impact of a powerful El Niño occurrence that took place in that time period. Additionally, they aim to gain insight into the characteristics of Typhoon Cobra, a tropical storm in 1944 that resulted in the sinking of three American destroyers and the deaths of approximately 800 sailors.

Teleti stated that the sailors’ dedication to their work was a source of inspiration. He also mentioned that it is unlikely they imagined anyone would be reviewing their observations 80 years later.

“Kimberly M. S. Cartier, a staff writer, can be found on Twitter as @AstroKimCartier.”

This article is part of our ENGAGE resource, which provides educators with science news for their classroom lessons. Check out all the ENGAGE articles and let your fellow educators know how you used this article in a comment below.

Citation: Cartier, K. M. S. (2023), Crowdsourced science pulls off a daring WWII data rescue, Eos, 104, Published on 20 October 2023.
Text © 2023. AGU. CC BY-NC-ND 3.0

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