Ice fronts from the early 19th century were far more advanced around the Arctic than they are today, researchers analysing whalers' log books from this time have discovered.
The findings have been revealed as part of the ARCdoc research project, led by the University of Sunderland, which analyses historical logbooks recorded by explorers, whalers and merchants during epic expeditions, between 1750 and 1850. The project aims to increase our scientific understanding of climate change in this environmentally important region. The logbooks include famous voyages such as Parry's polar expedition in HMS Hecla and Sir John Franklin's lost journey to navigate the Northwest Passage.
Some of the most significant data to emerge from the project has come from painstaking analysis of 60 log books belonging to whaling vessels, which contain descriptions of sea ice advancing and retreating every summer, all of which were recorded by whalers who ventured farther north than anyone else.
Phd Student Matthew Ayre has mapped what the ice was doing during that 100 year period, around the Davis Straits area, and at a time pre-dating the emergence of anthropogenic greenhouse gases in the atmosphere. A comparison with satellite data from the last 30 years of this area shows the ice was far more advanced than it is today.
Dr Dennis Wheeler said: "Significantly this is the first time we have ever had direct observational information on the ice fronts in the North Atlantic and Davis Straits area before 1900. Until the introduction of satellite information from the 1970s, we didn't know what the ice was doing. Well, now we know that it was more advanced, therefore the retreat of the ice in the last 30 years is part of a more recent and new pattern of climate change, so these log books contain absolutely vital climatologically information.
"We've only focussed on the North Atlantic and Davis Straits area which is a key driver in the global climatic system, and we have evidence of significant changes in frequency of rain, gales and snow.
"As a result of this data, you can begin to build up a clearer picture of climate change, before human impact begins to exercise any control on the global climate, this is the Arctic under natural weather conditions.
"We now need to ask some significant questions based on this empirical data of climate variation -- what is driving this, is it solar influences, volcanoes or internal changes in oceanic circulation? Those answers could give us the key to understanding the climate of the past and that means if you want to predict the future climate, you can do so with a little bit more confidence than we do now."
To understand how the data relates to today's ice cover decline, Matthew Ayre had to translate the whalers' archaic terminology into the first ever sea ice dictionary in standard 21st Century observational vocabulary. To do this he has traced every sea ice definition in UK history from satellite data of the last three decades, to the accounts of renowned Arctic explorer, scientist and Whitby whaler William Scoresby Jnr (1789-1857). Scoresby wrote an account of the Arctic regions and also deciphered some of the log books' terminology.
Matthew was also able to validate his data and the accuracy of his dictionary on board the Coast Guard Cutter Healey, a research vessel and the US's only operating polar ice breaker, where he spent five weeks recording what was happening to the ice.
Matthew explained: "I was making observations every four hours on board Healey, using Scoresby's definitions, comparing them to my dictionary and the Healy researchers' own daily records, testing how accurate our data is to validate what is in the sea ice dictionary."
He added: "Apart from modern-day research vessels, these are the only books in history from ships which seek out the ice edge in great detail and follow it. They describe various type of ice from 'loose' to 'heavy'; using this data I was able to map the ice edge, which has never been done before in any great detail because it melts and freezes every year. For example we found that if you work your way through the months August to September which is the time of maximum melt, data shows in Baffin Bay, there was a persistent feature of middle ice in the early 19th century, which is not there today."
The log books of up to 20 whaling voyages were analysed, including records from a fleet owned by the Newcastle-based Palmer family and data from the Hudson Bay Company, one of the oldest commercial companies in the world. Researchers believe as well as climatological data, the logbooks will be of great interest to those academics working on the social and economic history of whaling.
The three-year project has been funded by the Leverhulme Trust, led by Dr Dennis Wheeler, in collaboration with the Scott Polar Research Institute, The MET Office Hadley Research Centre and Hull University's Maritime Studies Unit.
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