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201527Jul21:32

Mam­moths killed by global warm­ing, not ice age!

Infor­ma­tion
pub­lished 27 July 2015 | mod­i­fied 27 July 2015
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MammothNew research revealed abrupt warm­ing, that closely resem­bles the rapid man-​made warm­ing occur­ring today, has repeat­edly played a key role in mass extinc­tion events of large ani­mals, the megafauna, in Earth’s past.

Using advances in analysing ancient DNA, radio­car­bon dat­ing and other geo­logic records an inter­na­tional team led by researchers from the Uni­ver­sity of Ade­laide and the Uni­ver­sity of New South Wales (Aus­tralia) have revealed that short, rapid warm­ing events, known as inter­sta­di­als, recorded dur­ing the last ice age or Pleis­tocene (60,00012,000 years ago) coin­cided with major extinc­tion events even before the appear­ance of man.

In the arti­cle pub­lished online on 23 July in the jour­nal Sci­ence, the researchers say by con­trast, extreme cold peri­ods, such as the last glacial max­i­mum, do not appear to cor­re­spond with these extinctions.

This abrupt warm­ing had a pro­found impact on cli­mate that caused marked shifts in global rain­fall and veg­e­ta­tion pat­terns,” said lead author Pro­fes­sor Alan Cooper.

Even with­out the pres­ence of humans we saw mass extinc­tions. When you add the mod­ern addi­tion of human pres­sures and frag­ment­ing of the envi­ron­ment to the rapid changes brought by global warm­ing, it raises seri­ous con­cerns about the future of our environment.
Prof Alan Cooper, Direc­tor Aus­tralian Cen­tre for Ancient DNA, Uni­ver­sity of Adelaide »

The researchers came to their con­clu­sions after detect­ing a pat­tern, 10 years ago, in ancient DNA stud­ies sug­gest­ing the rapid dis­ap­pear­ance of large species. At first the researchers thought these were related to intense cold snaps.

How­ever, as more fossil-​DNA became avail­able from museum spec­i­men col­lec­tions and through improve­ments in car­bon dat­ing and tem­per­a­ture records that showed bet­ter res­o­lu­tion through time, they were sur­prised to find the oppo­site. It became increas­ingly clear that rapid warm­ing, not sud­den cold snaps, was the cause of the extinc­tions dur­ing the last glacial maximum.

The research helps explain fur­ther the sud­den dis­ap­pear­ance of mam­moths and giant sloths that became extinct around 11,000 years ago at the end of the last ice age.

It is impor­tant to recog­nise that man still played an impor­tant role in the dis­ap­pear­ance of the major mega fauna species,” said fel­low author Pro­fes­sor Chris Tur­ney from the Uni­ver­sity of New South Wales.

The abrupt warm­ing of the cli­mate caused mas­sive changes to the envi­ron­ment that set the extinc­tion events in motion, but the rise of humans applied the coup de grâce to a pop­u­la­tion that was already under stress.”

In addi­tion to the find­ing, the new sta­tis­ti­cal meth­ods used to inter­ro­gate the datasets (led by Ade­laide co-​author Pro­fes­sor Corey Brad­shaw) and the new data itself has cre­ated an extra­or­di­nar­ily pre­cise record of cli­mate change and species move­ment over the Pleistocene.

This new dataset will allow future researchers a bet­ter under­stand­ing of this impor­tant period than has ever been pos­si­ble before.


(Source: Uni­ver­sity of Ade­laide media release, 24.07.2015)


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