reality of climate change - the trees don't lie

reality of climate change – the trees don’t lie

A few weeks ago, I was standing in awe of the forest giants in the world’s second largest temperate rainforest, the Tarkine, in Tasmania’s north-west. Little did I know that these trees are silent recorders of the environment. Not until Mike Peterson, an experienced forester, unlocked the secrets of dendrochronology – or tree ring analysis.

Many trees produce a single ring of growth in a year. Because climate and environment affect the way trees grow, the size of the annual rings varies from year to year. Dendrochronology requires knowledge of the exact years during which individual rings grew, which is achieved by carbon dating technology. In Tasmania, 1500 year old Huon pines from Mount Read have been cored with a small 5mm increment borer, and with other samples from dead tress and partially buried logs in the stand, it has been possible for tree ring scientists to develop a chronolgy of more than 4000 years.

Climatologists use the statistical association between ring width and weather data to estimate climate variation in the past. Mike sidled up to the back of his ute and pulled out some cores from old Huon Pine specimens that dated back more than 1000 years. He then showed me his published work, in conjunction with the University of Tasmania, on temperature variation over this period. Guess what? There was about 0.5 degrees Celsius of average variation for the entire 1000 year period until we get to the 1960′s. From that time on, the tree rings suggest that temperatures have climbed an incredible 1.0 to 1.5 degrees Celsius in an unbroken upward trend line. The trees don’t lie. They are detecting and recording global warming, deep in the Tasmanian rainforest.

I was amazed at what I’d been shown, not that I need any convincing about global warming, and the contribution of man to it – and yet the sceptics continue to give our decision makers licence to stall action. John Quiggin (AFR Feb 3, 2011 – no hyperlink because of Fairfax content charging policy!) captures my perspective when he argues that “the spoilers generally lack the understanding of basic statistical analysis of trends in time series, or the fundamentals of the greenhouse effect. Worse, they haven’t bothered to learn”. Regardless of their scepticism in the light of overwhelming scientific evidence, it would be pretty hard for these people to mount effective arguments against the evidence that I saw – presented first hand by the mighty Huon Pines of  Tasmania.

If you’re really interested in the subject, then you might even be interested in attending the second Asian Dendrochronology Conference in Xian, China in August 2011! And I’ve just heard that the next major international conference “World Dendro 2014″, will be held in Melbourne, with several excursions and field studies planned for Tasmania.