What drives interannual variation in tree ring oxygen isotopes in the Amazon?

In a new study, LEAF scientists use the isotopes present in tree rings to examine rainfall across the Amazon basin.

Developing a good understanding of past climate is vital when trying to interpret ongoing, and predict future, climate changes. This can be challenging in regions such as Amazonia where weather station data are particularly limited.

In remote regions like this, other means of reconstructing the historical climate are needed. Tree rings are an example of a natural climate record, with each ring recording information about the environment during the period of its formation.

To use tree ring characteristics as a proxy for past climate it is important to understand exactly how climate influences the signal stored in the wood.

In a study published recently in Geophysical Research Letters, LEAF scientists from the School of Geography and the School of Earth and Environment looked at the factors controlling the ratio of light and heavy oxygen atoms in tree rings from northern Bolivia. The isotopes in these tree rings have been shown to be a good indicator of rainfall over the whole Amazon basin.

The researchers used a model to reconstruct the transport of air over the continent, and examine large-scale moisture flow into, and out of, the basin. They found that the dominant factor controlling the tree ring oxygen signal is the amount of rain that falls during air travel.

Lead author on the study, Jessica Baker said, "This result is important because it shows that oxygen isotope ratios in tree rings, and other natural archives, can be reliably used to reconstruct Amazon rainfall."

You can read the original article here.