How severe can climate change become in a warming world? Worse than anything we've seen in written history, according to results of a study appearing this week in the journal Science.
An international team of scientists led by Curt Stager of Paul Smith's College, New York, has compiled four dozen paleoclimate records from
sediment cores in
Lake Tanganyika and other locations in Africa.
The records show that one of the most widespread and intense droughts of the last 50,000 years or more struck Africa and Southern Asia 17,000 to 16,000 years ago.
Between 18,000 and 15,000 years ago, large amounts of ice and meltwater entered the North
Atlantic Ocean, causing regional cooling but also major
drought in the tropics, says Paul Filmer, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research along with NSF's Division of Atmospheric and Geospace Sciences and its Division of Ocean Sciences.
"The height of this time period coincided with one of the most extreme megadroughts of the last 50,000 years in the Afro-Asian monsoon region with potentially serious consequences for the Paleolithic humans that lived there at the time," says Filmer.
The "H1 megadrought," as it's known, was one of the most severe climate trials ever faced by anatomically modern humans.
Africa's
Lake Victoria, now the world's largest tropical lake, dried out, as did Lake Tana in Ethiopia, and Lake Van in Turkey.
The Nile, Congo and other major rivers shriveled, and Asian summer monsoons weakened or failed from China to the Mediterranean, meaning the
monsoon season carried little or no rainwater.
What caused the megadrought remains a mystery, but its timing suggests a link to Heinrich Event 1 (or "H1"), a massive surge of icebergs and
meltwater into the North Atlantic at the close of the last ice age.
