From The Sunday Times

August 3, 2008

Captains' logs yield climate clues

Records kept by Nelson and Cook are shedding light on climate change

Jonathan Leake

Britain's great seafaring tradition is to provide a unique insight into modern climate change, thanks to thousands of Royal Navy logbooks that have survived from the 17th century onwards.

The logbooks kept by every naval ship, ranging from Nelson's Victory and Cook's Endeavour down to the humblest frigate, are emerging as one of the world's best sources for long-term weather data. The discovery has been made by a group of British academics and Met Office scientists who are seeking new ways to plot historic changes in climate.

"This is a treasure trove," said Dr Sam Willis, a maritime historian and author who is affiliated with Exeter University's Centre for Maritime Historical Studies.

"Ships' officers recorded air pressure, wind strength, air and sea temperature and other weather conditions. From those records scientists can build a detailed picture of past weather and climate."

A preliminary study of 6,000 logbooks has produced results that raise questions about climate change theories. One paper, published by Dr Dennis Wheeler, a Sunderland University geographer, in the journal The Holocene, details a surge in the frequency of summer storms over Britain in the 1680s and 1690s.

Many scientists believe storms are a consequence of global warming, but these were the coldest decades of the so-called Little Ice Age that hit Europe from about 1600 to 1850.

Wheeler and his colleagues have since won European Union funding to extend this research to 1750. This shows that during the 1730s, Europe underwent a period of rapid warming similar to that recorded recently - and which must have had natural origins.

Hints of such changes are already known from British records, but Wheeler has found they affected much of the north Atlantic too, and he has traced some of the underlying weather systems that caused it. His research will be published in the journal Climatic Change.

The ships' logs have also shed light on extreme weather events such as hurricanes. It is commonly believed that hurricanes form in the eastern Atlantic and track westwards, so scientists were shocked in 2005 when Hurricane Vince instead moved northeast to hit southern Spain and Portugal.

Many interpreted this as a consequence of climate change; but Wheeler, along with colleagues at the University of Madrid, used old ships' logs to show that this had also happened in 1842, when a hurricane followed the same trajectory into Andalusia.

The potential of Royal Navy ships' logs to offer new insights into historic climate change was spotted by Wheeler after he began researching weather conditions during famous naval battles. Later, as global warming moved up the scientific agenda, he and others realised that the same data could shed light on historic climate change.

He said: "British archives contain more than 100,000 Royal Navy logbooks from around 1670 to 1850 alone. They are a stunning resource."

Most of these earlier documents contain verbal descriptions of weather rather than numerical data, because ships lacked the instruments to take numerical readings. However, Wheeler and his colleagues found early Royal Navy officers recorded weather in consistent language.

"It means we can deduce numerical values for wind strength and direction, temperature and rainfall," he said. The information will ultimately contribute to the International Comprehensive Ocean-Atmos-phere Data Set, a global database maintained by the National Oceanic and Atmospheric Administration, a US government agency.

Wheeler makes clear he has no doubts about modern human-induced climate change. He said: "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. These records will give us a much clearer picture of what is really happening."

The Met Office has also set up a project, part-funded by Defra, the environment ministry, to study 900 logbooks kept by the East India Company on voyages between Europe and the Far East between 1780 and 1840. Its vessels carried thermometers and barometers so the data is of higher quality.

Faced with logs taken over so many voyages, the researchers have had to be selective. One of the most avid recorders of such data was Nelson himself, whose personal logbook records the air pressure and other readings he took up to several times daily.