If some scientists are correct, 536 A.D. might have been the year of a double comet impact that caused tsunamis and cooled the Earth for a decade. While many scientists who study the likelihood of a collision between Earth and a large meteor, comet or asteroid discount the possibility of major events in the Holocene era, a few scientists are looking carefully at the evidence.
Holocene Impact Working Group
In a 2010 National Geographic article Richard Lovett wrote about the Holocene Impact Working group and the hypothesis that a space lump impacted Earth in the Gulf of Carpentraria in Australia, article here. The impact location is between Australia and New Guinea. While Sidney occupies south eastern Australia and Perth is in the south west, this gulf is a sparsly settled area of the continent.
Tunguska event
In 1908 a strange explosion, 1,000 times larger than Hiroshima struck Siberia, Russia. We now know the a space rock exploded above the Earth, and the story of a man at a trading post 40 miles from the center (who survived) is retold here. The event tore up 800 square miles of forest, roughly the size of Lake Okeechobee in Florida. Had the event occured directly over Berlin, which is west a ways, two million people could have been killed or harmed. Luckily, large cities are really just pinpricks on our globe.
2002 Eastern Mediterranean event
In this Telegraph article the 2002 event is mentioned at the end. High in the upper atmosphere, south of Greece and north of Benghazi, it occured in the middle of the Meditarranean Sea.
Chelyabinsk meteor
Feb. 15, 2013 was the first time video cameras caught one of these events on a large scale. Earthsky did a three year hence post mortem, where in a city 800 miles east of Moscow 100’s were injured and dashboard cameras and video surveillance captured the deafening bang and blinding light of the explosion. According to Wikipedia, 7,200 buildings were damaged in six cities near Chelyabinsk, probably mostly broken windows.
Changing interpretations of dinosaur extinction since 1970
In 1970, climate change was probably the top theory for the extinction of the dinosaurs 66 million years ago. By 1980 a theory of Walter Alvarez and colleagues, began to garner wider adoption among scientists. Worldwide iridium layer geology and the identification of the impact site off the Yucatan Peninsula are now accepted as being the top contributor to the decline of the thunder lizards. Some scientists say the destruction may have wiped out entire populations in a matter of hours.
February 6, 2016 event
Feb. 6 fireball fell into the ocean off the coast of Brazil and released energy roughly equivalent to 13,000 tons of TNT. This is significantly less than the Chelyabinsk impact, which injured more than 1,000 people with the equivalent of 500,000 tons of TNT
Clovis Man
Clovis man, the Sabre Tooth Tiger, the Wooly Mammoth, the Mastadon, and the Giant Sloth all inhabited North America yet disappeared 12,900 years ago. Scientists have always blamed this on climate change, or on Clovis Man himself, conjecturing that Clovis Man killed off the animals, destroying his food supply and starved himself to death.
But a geological layer called the Black Mat is being studied, and some, including the Holocene Impact Working Group, are looking closely at other possibilities. This recent extinction may not, after all, be the fault of Clovis Man and their Suburban Utility Vehicles.
Sometimes called the Younger Dryas impact hypothesis, geologists are dissecting a layer of earth from several dozen Clovis sites across the continent, and always finding a carbon rich layer of burnt material that can be dated to 12,900 years ago. One piece of yellow pine showed ‘vitrification’ on one side, evidence of a brief exposure to a temperature in excess of 6,000 degrees F.
However, much debate is ongoing as to the meaning of the black layer, and evidence cannot be neatly organized. Clovis man is thought to have crossed the ice bridge from Siberia to Alaska, a route that melted and ceased to exist around 10,000 years ago. Critics claim that Megafauna declined 1,000 years earlier, and ask why Bison and Brown Bears survived such an event.