A new study has examined supernovae explosions that happened 2.5 and 8 million years ago to determine if these occurrences could be linked with mass extinctions here on Earth. At the time of the supernova explosion 2.5 million years ago, our planet was just entering the Ice Age or Pleistocene era after the end of the Pliocene, which was a decidedly warmer time for Earth.
While it is certainly possible that changes in our planet’s orbit and wobble could have greatly contributed to climate change that was happening at the time, new research conducted by Washburn University’s Dr. Brian Thomas has delved deeply into whether the occurrence of a supernova at the same time could have helped to cause large extinctions, or at the very least changes to life on Earth, as Phys.org reports.
The supernova explosion that occurred 2.5 million years ago would have been approximately 163 to 326 light-years away from our planet, which is an astonishingly long distance. But could the ionizing radiation that happened as a direct result of this event have affected Earth at the time?
When looking at fossil records from 2.5 million years ago, Dr. Thomas noted that “there were changes, especially in Africa, which went from being more forested to more grassland.” There was also a concentration worldwide of elevated levels of iron-60, which is a consequence of a supernova, and Thomas was interested in learning if there was a connection between these events.
“We are interested in how exploding stars affect life on Earth, and it turns out a few million years ago there were changes in the things that were living at the time. It might have been connected to this supernova.”
While there were no mass extinctions during the divide of the Pliocene and Pleistocene eras, if you look at the number of extinctions that occurred overall, these still would have been much higher than normal.
Dr. Brian Thomas has observed that the general consensus appears to be that a “supernova goes off and everything dies,” but notes that this is not at all factual. For instance, harmful cosmic rays occurring afterward would not happen immediately, and these rays, along with “radioactive iron rain,” could end up taking so long that it could be hundreds of thousands of years before they occurred.
What would happen first, according to Dr. Thomas, is that the earth would be struck by higher energy particles. Thomas looked at models to determine at what levels ozone would be at on Earth 100, 300, and 1,000 years after the supernova explosion to determine how much ozone would have been depleted during these times. Three hundred years after the supernova, it was determined that the depletion in ozone was at its highest point.
As Dr. Dimitra Atri of Seattle’s Blue Marble Space Institute of Science explained, this new study is hugely important as any decrease in ozone is likely to have a major effect on life on Earth.
“This work is an important step towards understanding the impact of nearby supernovae on our biosphere.”
In terms of mass extinctions on Earth after such supernovae explosions, Dr. Thomas has concluded that what it boils down to is that some species and organisms will die off, while others may thrive. For instance, wheat and soybeans appear to grow spectacularly well after such an event, while other crops dwindle.
“There is a subtler shift. Instead of a ‘wipe-out everything,’ some organisms are better off and some are worse off.”
The new study on the link between mass extinctions on Earth and supernovae explosions has been published in the journal Astrobiology.