There is nothing like Lake Agassiz today so I’m not too worried. No chance Greenland will melt in one day.
——glacial Lake Agassiz in North America burst its banks and poured into the North Atlantic and Arctic Oceans.-—
Just because there is nothing like Lake Agassiz today, doesn’t mean there is nothing to worry about. One of the risks of global warming is the total summer melting of the Arctic ice cap. Normally as the Gulf Stream flows north, it hits freezing weather, and the surface water freezes. This concentrates the salt below it making the water heavier so it flows to bottom of the ocean and moves back toward to Equator. This is called the North Atlantic Oscillation, NAO, or North Atlantic Deep Water, NADW. You can Google those terms for more details. Thus, no arctic ice, no significant freezing, and the NAO grinds to a halt. No warm water for the British Isles or Europe. Do you realize how much further north they are than we are.
At any rate, I think the Firestone Book that Sunken Civ has made us aware of is more likely the answer, although I think it could have caused a significant impact on Lake Agassiz too. This book hypothesizes a major boloid strike(s) in North America at the same time, wiping out the megafauna and the Clovis culture. Also there was another big outflow of Agassiz around 8,400 years ago, which may also have had a worldwide inpact