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https://theconversation.com/africa-dramatically-dried-out-5-500-years-ago-our-new-study-may-warn-us-of-future-climate-tipping-points-229323>
"Around five and half millenia ago, northern Africa went through a dramatic
transformation. The Sahara desert expanded and grasslands, forests and lakes
favoured by humans disappeared. Humans were forced to retreat to the mountains,
the oases, and the Nile valley and delta.
As a relatively large and dispersed population was squeezed into smaller and
more fertile areas, it needed to innovate new ways to produce food and organise
society. Soon after, one of the world’s first great civilisations emerged –
ancient Egypt.
This transition from the most recent “African humid period”, which lasted from
15,000 to 5,500 years ago, to the current dry conditions in northern Africa is
the clearest example of a climate tipping point in recent geological history.
Climate tipping points are thresholds that, once crossed, result in dramatic
climate change to a new stable climate.
Our new study published in
Nature Communications reveals that before northern
Africa dried out, its climate “flickered” between two stable climatic states
before tipping permanently. This is the first time it’s been shown such
flickering happened in Earth’s past. And it suggests that places with highly
variable cycles of changing climate today may in some cases by headed for
tipping points of their own.
Whether we will have any warnings of climate tipping points is one of the
biggest concerns of climate scientists today. As we pass global warming of
1.5˚C, the most likely tipping points involve the collapse of ice sheets in
Greenland or Antarctica, tropical coral reefs dying off, or abrupt thawing of
Arctic permafrost.
Some say that there will be warning signs of these major climate shifts.
However, these depend very much on the actual type of tipping point, and the
interpretation of these signals is therefore difficult. One of the big
questions is whether tipping points will be characterised by flickering or
whether the climate will initially appear to become more stable before tipping
over in one go."
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
