A huge asteroid may have hit the world 12,800 years ago causing global climate change and extinction, according to a study.
Evidence to support the theory that one or more asteroids triggered global cooling and the extinction of large animals has been uncovered in South Africa.
A team of scientists discovered signs of a ‘platinum spike’ suggesting a meteor had hit – meteorites are rich in platinum – at a site called Wonderkrater in the Limpopo Province, north of Pretoria in South Africa.
The researchers say the platinum spike supports the The Younger Dryas Impact Hypothesis – which posits that a large asteroid hit the Earth and caused a mini ice age that wiped out dozens of species including mammoths and severely reduced Earth’s human population.
Researchers have discovered their first evidence in the southern hemisphere that a mini ice age almost 13,000 years ago may have been caused by clouds of dust thrown up by an asteroid impact (stock image)
Until now, proof that meteoroids had impacted during that period and potentially led to a mini-ice age had only been documented across the northern hemisphere.
A total of 28 areas with high levels of platinum had been found.
But now evidence to suggest similar sites are present in the southern hemisphere has been uncovered.
Findings from researchers at the University of the Witwatersrand in Johannesburg, South Africa partially support the theory that meteorites crashed into earth, leading to consequences globally – along with another meteorite site discovered in Chile.
An episode of rapid cooling named the The Younger Dryas is a well documented period believed to contributed to the extinction of many species of large animals around 12,800 years ago.
While theories previously pointed to this post-ice age cooling as a result of changes in oceanic circulation systems, another theory was presented by American scientists in 2007 – that the cooling was triggered by the dust fall out of an asteroid impact.
Map shows location of Wonderkrater in South Africa. The yellow dots represent areas where spikes in platinum concentration have been found. Red dots show other areas of interest
Dust circulating in the atmosphere after an impact could have reduced the amount of sunlight reaching the earth, affecting plant growth and temperatures on earth.
Now Francis Thackeray of the Evolutionary Studies Institute at the University of the Witwatersrand in South Africa believes a platinum spike found in South Africa proves that the extinction of many large animals globally could have been caused by one or multiple meteoroid impacts.
Dr Thackeray who was working with researcher Philip Pieterse from the University of Johannesburg and Professor Louis Scott of the University of the Free State, said: ‘Our finding at least partially supports the highly controversial Younger Dryas Impact Hypothesis (YDIH).
‘We seriously need to explore the view that an asteroid impact somewhere on earth may have caused climate change on a global scale.
‘And [it may have] contributed to some extent to the process of extinctions of large animals at the end of the Pleistocene, after the last ice age.’
Many mammals became extinct in North America, South America and Europe at the time of the Younger Dryas.
In South Africa a few extraordinary large animal species became extinct around that period including the giant African buffalo, a large zebra, and a very big wildebeest each weighing around 500kg more than its modern counterpart.
Human populations may also have been indirectly affected at the time in question.
Thackeray argues that a dramatic halt in the development of the use of stone tools by the Clovis people in North America and the Robberg stone artefacts used by populations in South Africa around that period could indicate that an asteroid may have caused global consequences.
Dr Thackery said: ‘Without necessarily arguing for a single causal factor on a global scale, we cautiously hint at the possibility that these technological changes, in North America and on the African subcontinent at about the same time, might have been associated indirectly with an asteroid impact with major global consequences.’
A Meteor glowing as it enters the earth’s atmosphere (stock)
He added: ‘We cannot be certain, but a cosmic impact could have affected humans as a result of local changes in environment and the availability of food resources.’
At Wonderkrater, the team has also uncovered evidence from pollen to show that about 12,800 years ago there was temporary cooling.
This linked up with the ‘Younger Dryas’ drop in temperature that is well documented in the northern hemisphere, and now also in South Africa.
According to some scientists, this cooling in widespread areas could have been caused by the global dispersal of platinum-rich atmospheric dust after a meteorite hit.
Thackeray’s team believes their discovery of a platinum spike at about 12,800 years ago at Wonderkrater is just part of the strengthening view that an asteroid or cometary impact might have occurred at that time.
This is the first evidence in Africa for a platinum spike leading to the mini-ice age of the Younger Dryas.
Younger Dryas spikes in platinum have also been found in Greenland, Eurasia, North America, Mexico and recently also at Pilauco in Chile.
Wonderkrater is the 30th site in the world discovered with evidence of platinum spikes.
Thackeray said: ‘Our evidence is entirely consistent with the Younger Dryas Impact Hypothesis.’
The discovery in South Africa is expected to be analysed in context with those made in other parts of the world.
A large crater 31 kilometres in diameter was discovered in northern Greenland beneath the Hiawatha Glacier last year.
Thackery recognises that the source of the platinum at Wonderkrater could hypothetically be cosmic dust that was dispersed in the atmosphere after a meteorite impact in Greenland.
The South African research has been supported by the National Research Foundation and the DST/NRF Centre of Excellence for the Palaeosciences and was published in Palaeontologia Africana.
