Ancient baobab trees may be key to future climate change forecasts
INFORMATION gleaned from ancient baobab trees is being used to test weather models, to see how accurate they are in forecasting future climate change.
Researchers have for the first time been able to compile an accurate record of South African rainfall over the last 1 000 years.
They did this through studying core samples and the tree rings of baobabs in Limpopo.
Trees produce growth rings on an annual basis and scientists were able to examine these in two dead baobabs. They also took core samples from live specimens.
Stephan Woodborne, of the National Research Foundation’s iThemba laboratories, and one of the authors of the scientific paper, said the rings provided a year by year record of rainfall.
“Previously people could only go back 200 years, by examining newspaper records,” Woodborne said. “What we have got here is very high resolution.”
The baobabs were dated by using carbon C14 dating. The oldest baobab the researchers found had an age of 1 355 years.
What they found were periods of reduced rainfall, including one that has been called the Little Ice Age, that lasted in the southern hemisphere from about 1550 to the early 1800s.
The Little Ice Age has been blamed by some academics for the fall of the Mapungubwe and Greater Zimbabwe civilisations.
This was also a period, Woodborne said, which saw other societies like that of the Bokoni in Mpumalanga adapt to the drier conditions by radically changing their farming methods.
He said they were using the data to test computer weather models over the same thousand year period. These models would be used to understand how climate change might occur in the future.
Meanwhile, the researchers have found baobabs in Namibia, Madagascar and Botswana which they will also use to obtain further data.