Scientists hope to unlock climate secrets in old trees

Scientists are hoping to get a global perspective of climate changes over the last 1,000 years by studying the rings in New Zealand's native kauri trees.

Researchers from New Zealand's National Institute of Water and Atmospheric Research (NIWA) say the trees, which can live for centuries and are unique to New Zealand, could provide a Southern Hemisphere perspective on climate events previously only recorded in the Northern Hemisphere.

Scientists from NIWA and the United States will examine precisely-dated kauri tree rings for highly-detailed "chemical signatures" that could indicate temperatures, storms, droughts, and winds in centuries past, said a statement from NIWA Wednesday.

The findings would provide information on New Zealand's past climate changes during periods such as the widely-documented Medieval Climate Anomaly (MCA), which occurred from around 1000 to 1400, and the Little Ice Age (LIA), which spanned the 16th to 19th centuries.

The MCA brought warmer temperatures, comparable to today's, to parts of Europe, while the LIA was a time of cooler temperatures and glacial advances in the Alps.

Dr Andrew Lorrey, of NIWA, who is leading the research team, said the study would indicate how these periods affected the Southern Hemisphere.

"We know very little from this part of the world. What types of changes occurred and when they occurred, and the timing and rate of changes, are very important. This information will help us better understand the factors influencing our regional climate. We are building a holistic picture of what happened in the past," Lorrey said in the statement.

The relationship between the hemispheres, and how the atmosphere and oceans interacted, was increasingly important to understanding the global climate, he said.

A better understanding of events in the Southern Hemisphere during critical climate intervals would help understanding of the causes and ramifications for future climate changes.

"If you are dealing with limited information - just a Northern Hemisphere perspective - there is very little that can be drawn out about the dynamics of our climate system here. To gain a full view of global climate change the whole picture needs to be presented," said Lorrey.

The "embedded chemical record" in kauri samples from living and recently dead trees, as well as building timbers, would contain valuable information.

The study would run from March next year to February 2015.