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Old ships' logs show temporary global warming in 1730s

Records interrupted only by looting of treasure galleons

A climate prof noted for data mining of archived ships' logs has produced further insights into global warming. Dr Dennis Wheeler of Sunderland Uni says his latest analysis shows sudden warming of the North Atlantic and Europe - much like that seen in recent times - during the 1730s.

This, Wheeler believes, shows that widespread rises in temperature of the kind recorded lately can be caused naturally. He thinks that human-caused carbon emissions are contributing to climate change now, but says it is unwise to link human emissions to specific events unless evidence is very strong.

“Global warming is a reality, but what our data shows is that climate science is complex and that it is wrong to take particular events and link them to CO2 emissions," Wheeler told the Times at the weekend.

Wheeler's new 1730s temperature spike info comes from trawling through mountains of archived ship's logs. Royal Navy logbooks have been particularly valuable, both for this project and previous ones.

“British archives contain more than 100,000 Royal Navy logbooks from around 1670 to 1850 alone," says Wheeler. "They are a stunning resource.”

The new research, compiled by Wheeler and colleagues from the Met Office and other institutions, is to be published in the journal Climatic Change. The paper has already gained a good deal of ink in the UK media, generally referencing Admiral Nelson and Captain Cook for their zeal in keeping accurate records.

As neither Cook nor Nelson were at sea during the 1730s, this seems a bit unreasonable. Perhaps the most famous British naval officer active at the time was Captain (later Admiral) George Anson. Anson subsequently became a naval legend after his epic voyage round the world from 1740-44, during which he and his crew captured a Spanish treasure galleon in the Pacific - making the survivors who eventually got home to England rich men. Later, as an admiral, Anson also handed the French a massive kicking at Cape Finisterre and then became First Sea Lord - the head of the Navy.

During the 1730s - the period where Wheeler's sudden warming occurs - Captain Anson was at sea in the Atlantic, so it's likely that his logs form part of Wheeler's data set. However, it wasn't normal for warships to carry thermometers at the time, so much of the analysis draws on winds and the "consistent language" used by sea officers of the time, as well as European shore-based records. ®

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