The study of tree-rings, has been widely used to reconstruct historical variation in environmental conditions. Because trees are widely distributed, long-lived, and often form annual growth rings, they can provide unique insights into climate variability.
A tree ring is a seasonal growth increment made up of sequences of large thin walled tree cells, called earlywood, and more densely-packed thick-walled cells, known as latewood.
Where tree growth is limited by climate (e.g. temperature, rainfall), variation in the width, density and/or chemical composition of the annual growth rings can provide insights into climate variability for centuries into the past.
The SEARCH project is using tree ring records from Tasmania, Western Australia, New Zealand and Indonesia to reconstruct past rainfall patterns in the Australian region.