Everyone knows that you can age a tree by counting its rings, and the width of those rings is a record of climate. But do you need trees to track the climate?

Climate isn’t the same everywhere. The forthcoming El Niño event threatens parts of the world with droughts and other parts with floods. So in recreating models of past climates it’s helpful to be able to check your work against a wide data set.

Dendrochronology, the study of tree rings, is a useful tool for doing this. A tree has annual growth and it’s visibly marked in the structure of the tree, making rings as the trunk grows bigger. The width of these rings is a record of the climate for that year. During a wet year a tree may be able to put on more growth than during a drought. So take a sample from a trees and the rings give you a very tight match between the year and its climate.

Of course, that does mean you’re reliant on the area you’re looking at having trees.

Eryuan Liang and Dieter Eckstein have looked at the Tibetan plateau, where there are few trees, and thhey’ve found an alternative. They published a paper in Annals of Botany, Dendrochronological potential of the alpine shrub Rhododendron nivale on the south-eastern Tibetan Plateau, where they showed shrubs could be used instead.