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https://theconversation.com/madagascars-ancient-baobabs-store-700-years-of-climate-secrets-what-they-reveal-279387>
"Madagascar is home to seven species of baobab trees, of which six are found
nowhere else on the planet. Many of the trees have been alive for well over
1,000 years. The ancient trees have become symbols of Madagascar itself.
They’re also gifts to climate science.
Imagine these trees as filing cabinets for climate history. Every year a tree
grows, it lays down a new ring, and locked inside that ring are chemical
fingerprints that reveal how much rain fell that year.
These records could tell society what it needs to know about the climate
history of Madagascar. But until now, this information was hidden in the trunks
of the trees.
We are a team of applied palaeoecologists and climate scientists who set out to
provide the first ever tree ring rainfall record reconstructed from isotopes in
baobab rings in Madagascar.
Isotopes are different forms of the same chemical element that have the same
number of protons but a different number of neutrons in their nucleus. Baobab
trees absorb carbon dioxide, which contains three carbon isotopes: carbon-12
(light, most common), carbon-13 (heavy, stable but less common), and carbon-14
(rare and radioactive).
The chemistry is elegant: in dry years, trees absorb more of a heavier form of
carbon because they close their stomata to conserve water, which leads to
higher absorption of ¹³C relative to normal conditions. In wet years, that
signal drops. String enough of these signals together, and combine them with
radiocarbon dating that establishes how old the trees are, and you have a
natural rain gauge running through the centuries – the first of its kind ever
produced for Madagascar.
Our research aimed to increase Madagascar’s palaeoclimate records. These are
records of temperature, rainfall and climate that span centuries and millennia.
When used along with other palaeoecological proxies such as pollen, they help
to show how ecosystems function and change over hundreds of years.
Most of the palaeoclimate records in Madagascar are found in mineral deposits
like speleothems, stalagmites and sediments, and to date there are not many.
Although scientists have previously used this method to generate a 1,000-year
rainfall record from baobabs for South Africa, this hadn’t been tried in
Madagascar.
Our goal wasn’t just academic. This kind of long-term evidence has direct,
practical relevance for biodiversity conservation, land management, and
building resilience to global warming."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
