Kauri trees offer unique climate data

Two British universities say they are racing the clock - and New Zealanders milling kauri trees preserved in swamps - to recover irreplacable climate records.

Scientists at Exeter and Oxford universities believe the trees hold the secret to understanding climate fluctuations spanning back to the end of the last Ice Age.

Oxford University archaeologist Professor Christopher Ramsey, said in a statement the trees gave a unique opportunity to increase climate knowledge.

"The radiocarbon measurements should give us important new data that will help us to understand interactions between the atmosphere and the oceans during this period when there was rapid and dynamic change," he said.

"Equally exciting is the prospect it will give us of more precise dating of archaeological sites from this period.

"We are facing a race against the clock to gather the information locked inside these preserved trees."

Exeter University has been awarded a grant by Britain's Natural Environment Research Council to carry out carbon dating and other analyses of the kauri tree rings.

It said in a statement that the trees - which live up to 2000 years and can be 4 metres thick - store an immense amount of information about rapid and extreme climate change in the past.

By analysing details such as wide ring widths associated with cool dry summer conditions, the researchers hope to extract very precise and detailed data on atmospheric carbon to plug a large gap in knowledge of climate change.

Historical weather records date back only to the mid-19th century.

Lead researcher Professor Chris Turney of Exeter University said there was nowhere else with such a rich resource of ancient wood spanning such a large period of time.

While various records existed for historic climate change, such as those derived from ice cores, there was no easy way of correlating these records. Though the British research will focus on the past 30,000 years, some trees recovered from Northland swamps date back 130,000 years.

Prof Turney said the unique archive of kauri trees was likely to be lost within the next 10 years because the swamp kauri were being rapidly extracted from the bogs and turned into furniture.

Samples from a network of sites with buried trees will be collected in New Zealand and taken back to the British laboratories for preparation and analysis at Exeter, then radiocarbon measurement at Oxford.

- NZPA