Remote cave study reveals 3000 years of European climate variation

June 15, 2015, University of New South Wales
Professor Andy Baker with part of a stalagmite from Roaring Cave in Scotland. A study of the limestone has produced a unique 3000-year-long record of climatic variations that may have influenced historical events including the fall of the Roman Empire and the Viking Age of expansion. Credit: Mediakoo/UNSW

University of New South Wales Australia-led research on limestone formations in a remote Scottish cave has produced a unique 3000-year-long record of climatic variations that may have influenced historical events including the fall of the Roman Empire and the Viking Age of expansion.

The study of five stalagmites in Roaring Cave north of Ullapool in north-west Scotland is the first to use a compilation of measurements to track changes in a climate phenomenon called the North Atlantic Oscillation.

'Our results also provide the longest annual record of this important phenomenon, which has a big impact on the climate in Europe,' says study leader, UNSW Professor Andy Baker.

'It confirms that the during the Medieval Warm Period between 1080 and 1430 the oscillation index was in an unusually prolonged positive phase, which brings increased rain to Scotland and drier conditions in the western Mediterranean,' says Baker, of the UNSW Connected Waters Initiative Research Centre.

'Our results also reveal there was another persistent positive phase between 290 and 550, which coincides with the decline of Rome and a period of intensified human migration in southern Europe during the Dark Ages.

'This was followed by a persistent negative phase between 600 and 900 which may have provided warm and dry conditions in northwestern Europe that made it suitable for westward expansion by the Vikings, although the precise timing of this event is contested.'

The study is published in the journal Scientific Reports.

The North Atlantic Oscillation climate index measures the air pressure difference between Iceland and the Azores islands off the Portuguese coast, and is a record of the strength of the westerly winds in the North Atlantic.

Roaring Cave in Scotland. A study of its limestone has produced a unique 3000-year-long record of climatic variations that may have influenced historical events including the fall of the Roman Empire and the Viking Age of expansion. Credit: UNSW

Roaring Cave, or Uamh an Tartair, in northwest Scotland, is a shallow cave beneath a blanket of peat that has accumulated during the past 4000 years.

Rainfall levels in this region closely correspond with the strength of the oscillation index in winter, with higher precipitation when it is positive. And the upward rate of growth of stalagmites in the cave is very sensitive to rainfall—the more water in the peat, the more slowly the stalagmites grow.

'We painstakingly measured the thickness of each annual growth ring in five stalagmites taken from the cave, including one that provides a continuous annual record spanning more than 1800 years,' says Baker.

By overlapping the five stalagmites they obtained a proxy record of the climate at the cave during a 3000-year period from about 1000 BC to 2000 AD.

'Our research provides a climate context for some of the big events in Europe and allows us to start building hypotheses about the impact of environment on societal change,' says Baker.

The team includes researcher from UNSW, the University of Lausanne in Switzerland and the University of Arizona in the U.S.

Explore further: Going underground to understand Australia's past climate variability

Related Stories

Research links two millennia of cyclones, floods, El Nino

March 31, 2015

Stalagmites, which crystallize from water dropping onto the floors of caves, millimeter by millimeter, over thousands of years, leave behind a record of climate change encased in stone. Newly published research by Rhawn Denniston, ...

Demise of last ice age encoded in tropical stalagmites

December 10, 2013

Hidden deep underground in Indonesian caves, the missing link in the demise of the last ice age has been uncovered in stalagmites, which have provided a 31,000 year-long record of Australasian monsoon activity.

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

denglish
1 / 5 (9) Jun 15, 2015
Wait. Are they saying that the climate changed cyclically before humans were heavily industrialized?

STOP THE PRESSES!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.