Baobab could settle climate-change debate

Sipho Masombuka
The baobab could hold the secret to the effects of climate change in Southern Africa over the past 1000 years.
Iconic baobab tree

Lead researcher Professor Stephan Woodborne, from the Pretoria University’s Mammal Research Institute, said scientists were able to date baobab trees very accurately using radio-carbon dating. And because baobabs can grow for over a thousand years, they can provide researchers with a rainfall record spanning centuries.

According to Woodborne, most records of rainfall patterns in South Africa date back to about 50 years, with only a few going back 100 years. He said this was not a long enough time to understand the climate system. He added: “When you look at rainfall variability over 1000 years it is possible to pick out what is driving the rainfall variability and how the rainfall systems are responding. We can see the impact of the temperature of the ocean in the Agulhas Current, for example, and the effect of El Niño, and other influences.”

Woodborne said the project started in 2008 when a baobab fell over in the Pafuri area, in the north of the Kruger National Park, and provided researchers with a good sample. “Subsequently we learned of a team that was working on baobabs and we partnered with them using the cores that they removed from baobab trees to procure more samples and get a robust climate pattern from the trees,” Woodborne said.

Woodborne explained that the process by which plants took carbon dioxide and water in and out through the leaves and roots was regulated by the availability of moisture. This, and the trees’ growth rings, showed how much rainfall there was since the time it formed. By measuring the carbon ratio in all the growth rings of a tree, the researchers can gather a record of rainfall over the course of the tree’s lifespan.

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