Global cooling investor Jo Nova writes:
Supernova caused lightning, which caused fires, which (maybe) caused humans to stand upright
Back in the unpoliticized Pliocene it’s possible that cosmic rays bombarded Earth and triggered lightning which started fires all around the Earth. This may (warning: speculation) have pushed human ancestors to stand on two legs.
In the politicized Holocene, however cosmic rays are “irrelevant”. Ancient cosmic rays can set the Earth on fire apparently, change dominant species, and leave a charcoal layer around the Earth. But changes in cosmic rays lately can *not* cause any changes in modern lightning and cloud cover...
The study reminds us that for most of human history Space Weather was important. It’s only modern climate models that decree astronomical-stuff = zero.
Another previous study showed that lightning strikes occur in time with the spinning Sun in 150 year old Japanese farm records.
Supernovae bombarded Earth with cosmic energy starting as many as 8 million years ago, with a peak some 2.6 million years ago, initiating an avalanche of electrons in the lower atmosphere…
The authors believe atmospheric ionization probably triggered an enormous upsurge in cloud-to-ground lightning strikes that ignited forest fires around the globe. These infernos could be one reason ancestors of Homo sapiens developed bipedalism — to adapt in savannas that replaced torched forests in northeast Africa.
“It is thought there was already some tendency for hominins to walk on two legs, even before this event,” said lead author Adrian Melott, professor emeritus of physics & astronomy at the University of Kansas. “But they were mainly adapted for climbing around in trees. After this conversion to savanna, they would much more often have to walk from one tree to another across the grassland, and so they become better at walking upright. They could see over the tops of grass and watch for predators. It’s thought this conversion to savanna contributed to bipedalism as it became more and more dominant in human ancestors.”
Based on a “telltale” layer of iron-60 deposits lining the world’s sea beds, astronomers have high confidence supernovae exploded in Earth’s immediate cosmic neighborhood — between 100 and only 50 parsecs (163 light years) away — during the transition from the Pliocene Epoch to the Ice Age.
“We calculated the ionization of the atmosphere from cosmic rays which would come from a supernova about as far away as the iron-60 deposits indicate,” Melott said. “It appears that this was the closest one in a much longer series. We contend it would increase the ionization of the lower atmosphere by 50-fold. Usually, you don’t get lower-atmosphere ionization because cosmic rays don’t penetrate that far, but the more energetic ones from supernovae come right down to the surface — so there would be a lot of electrons being knocked out of the atmosphere.”
REFERENCE
Adrian L. Melott, Brian C. Thomas. From Cosmic Explosions to Terrestrial Fires? The Journal of Geology, 2019; 000 DOI: 10.1086/703418
