New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt #ClimateChange for Earth
Published: October 22, 2019
"What kicked off the Earth’s rapid cooling 12,800 years ago?
"In the space of just a couple of years, average temperatures abruptly dropped, resulting in temperatures as much as 14 degrees Fahrenheit cooler in some regions of the Northern Hemisphere. If a drop like that happened today, it would mean the average temperature of Miami Beach would quickly change to that of current Montreal, Canada. Layers of ice in Greenland show that this cool period in the Northern Hemisphere lasted about 1,400 years.
"This climate event, called the #YoungerDryas by scientists, marked the beginning of a decline in #IceAge #megafauna, such as #mammoth and #mastodon, eventually leading to #extinction of more than 35 genera of animals across North America. Although disputed, some research suggests that Younger Dryas #environmental changes led to a population decline among the #NativeAmericans known for their distinctive #Clovis spear points.
"Conventional geologic wisdom blames the Younger Dryas on the failure of glacial ice dams holding back huge lakes in central North America and the sudden, massive blast of freshwater they released into the north Atlantic. This freshwater influx shut down #OceanCirculation and ended up cooling the climate.
"Some geologists, however, subscribe to what is called the impact hypothesis: the idea that a fragmented #comet or #asteroid collided with the Earth 12,800 years ago and caused this abrupt climate event. Along with disrupting the glacial ice-sheet and shutting down ocean currents, this hypothesis holds that the extraterrestrial impact also triggered an 'impact winter' by setting off massive #wildfires that blocked sunlight with their smoke.
"The evidence is mounting that the cause of the Younger Dryas’ cooling climate came from outer space. My own recent fieldwork at a South Carolina lake that has been around for at least 20,000 years adds to the growing pile of evidence.
"In the White Pond samples, we did indeed find high levels of platinum. The sediments also had an unusual ratio of platinum to palladium.
"Both of these rare earth elements occur naturally in very small quantities. The fact that there was so much more platinum than palladium suggests that the extra platinum came from an outside source, such as atmospheric fallout in the aftermath of an extraterrestrial impact.
"My team also found a large increase in soot, indicative of large-scale regional wildfires. Additionally, the amount of fungal spores that are usually associated with the dung of large herbivores decreased in this layer compared to previous time periods, suggesting a sudden decline in ice-age megafauna in the region at this time."
Full article:
https://theconversation.com/new-evidence-that-an-extraterrestrial-collision-12-800-years-ago-triggered-an-abrupt-climate-change-for-earth-118244
Greg Cocks 
From conductivity, we can calculate salinity of the water. 
