Dendrochronologists working in the US South West and in Mexico study tree rings on ancient tree stumps to establish historical weather.
David Stahle explains how he can read a detailed picture of the weather during the 16th Century. The tree ring record reveals that Central America suffered the worst drought in 500 years, it’s known as the ‘Mega Drought’. Stahle’s analysis also uncovers a pattern – 1545 and 1576 were anomalous years – when Mexico experienced heavy rain after prolonged drought.