Old Weather is a crowd-sourcing effort to transcribe ship’s logs from the 19th and early 20th centuries. This task can’t be performed by computers because of the diverse and idiosyncratic handwriting.
Data about past weather and sea-ice conditions are vital for climate scientists, while historians value knowing about the course of a voyage and the events that transpired. Since many of these logs haven’t been examined since they were originally filled in by a mariner long ago you might even discover something surprising.
Millions of weather, ocean, and sea-ice observations recorded by mariners and scientists over the past 150 years are being recovered by Old Weather. These data are made freely available in digital formats suitable for climate model assimilation, retrospective analysis (reanalysis), and other kinds of research. The performance of data-assimilating modeling and extended reanalysis systems is greatly improved, the uncertainty of results (especially in sparsely observed regions like the Arctic) is reduced, and new long-period calibration and validation data sets are being created. As the historical data resource is extended farther back in time it will be possible to study a wider range of weather and climate phenomena and to better understand their impact on the Arctic and global environment, now and in the future. (Source)