500 BC. In Rome, King Tarquin the Proud has been sent into exile and there’s a brand new Roman republic. At around the same time, in what is now Zimbabwe, an elephant defecates after feasting on baobab fruits. A seed sprouts in the dung.
That tree grew for nearly 2500 years. It grew as the Roman Empire rose and fell, and the Kingdom of Zimbabwe flourished and collapsed, and as British colonisers came and left. The Panke baobab was the oldest flowering tree in the world until 2010 – when it collapsed and died.
Sadly, it is not the only one of these venerable trees to die recently. In the past 12 years, 9 of the 13 oldest baobab trees in Africa, and 5 of the 6 largest, have died. The world has lost some of its greatest living treasures, and climate change is the leading suspect.
“The loss of the largest and oldest baobabs is a wake-up call for the dramatic climate change which has started to affect many areas of the world, especially southern Africa,” says botanist Adrian Patrut of Babeş-Bolyai University in Romania.
His team estimates that the number of baobabs in Africa has halved since 1960, due to climate change, logging and the loss of the large mammals that spread the trees’ seeds. “We believe that the African baobab should be considered endangered,” Patrut says.
In 2005, Patrut and colleagues in South Africa set out to study the growth patterns of African baobabs (Adansonia digitata).
These are the longest-living and largest flowering trees in the world, with wood volumes of up to 500 cubic metres. However, there are longer-lived and bigger non-flowering trees. The oldest bristlecone pine is more than 5000 years old, and the biggest giant sequoia has a wood volume of nearly 1500 cubic metres.
Patrut’s team studied and carbon-dated around 60 of the oldest baobab trees in Africa. As they worked, many of the trees died. The oldest parts of the 2100-year-old Dorslandboom in Namibia fell over and died in 2006; the 2000-year-old Glencoe tree in South Africa died in 2009; and the 1400-year-old Chapman tree in Botswana collapsed and died in 2016.
"We found many young and medium-aged baobabs fallen and dead, especially in southern Africa."
There was an outbreak of a disease called black sooty bark mould between 2000 and 2010, he says. However, the vast majority of the dead trees showed no signs of disease. Instead, the team attributes the deaths to the climate becoming more extreme – not just hotter, but with more intense droughts and floods.