Cosmic dust resulting from an enormous asteroid collision in outer space caused Earth to freeze, triggering an explosion in biodiversity 466 million years ago. A 93-mile (150km) wide asteroid ruptured between Mars and Jupiter, flinging vast quantities of dust towards Earth, blocking sunlight and causing dramatic global cooling. The dust floated down to Earth over a period of 2 million years, meaning the cooling was gradual enough for species to adapt.
New animals evolved to survive in regions with different temperatures.
This the first time it’s been shown that dust from an asteroid break-up can lead to cooling that triggers an ice age on Earth
Professor Birger Schmitz
Professor Birger Schmitz, of Lund University in Sweden, said: “This the first time it’s been shown that dust from an asteroid break-up can lead to cooling that triggers an ice age on Earth.”
Evidence from rock formations suggests that Earth experienced the short-lived ice age.
The dramatic temperature drop turned water into ice covering much of the planet, causing sea levels to fall globally.
The period coincided with an apparent spike in the diversity of life on Earth, much of which was still in the oceans.
In the hope of learning more about the ice age, Professor Schmitz’s team searched for evidence in ancient limestone in southern Sweden and near St Petersburg.
The researchers specifically looked for remnants of the huge asteroid, dubbed the “L chondrite parent body” by geologists.
The researchers dissolved with acid more than a ton of limestone of different ages from the sites.
They found the abundance of grains matching its chemical make-up rose by between 1,000 and 10,000 times after the asteroid’s annihilation.
These levels remained high for up to four million years.
Professor Schmitz added: “The grains come with the dust so when you see an increase in these, you know there’s been an increase in the dust.”
Scientists call the resulting explosion in marine life at the time the Great Ordovician Bio-diversification Event (GOBE).
Professor David Harper, a palaeontologist at Durham University who worked on the study, said it was “the most spectacular hike in marine diversity in the history of life”.
He added: “Ice ages have been associated with major volcanic eruptions, but for the first time the team has implicated asteroid-derived dust in the initiation of global cooling and a major leap in biodiversity that changed marine ecosystems forever.”
Researchers have cautioned against proposals to carry out geoengineering to create a similar dust shower to combat global warming.
Professor Philipp Heck of the University of Chicago said: ““Geoengineering proposals should be evaluated very critically and very carefully, because if something goes wrong things could become worse than before.”
Source: Read Full Article