The leading mainstream explanation involves Lake Agassiz — an ancient lake larger than all five Great Lakes combined. When an ice dam failed, massive amounts of cold fresh water surged through the Mackenzie River Valley into the North Atlantic. Since fresh water floats atop denser salt water, it essentially stalled the Atlantic conveyor belt, cutting off the hemisphere's primary heat transport. Climate models reproduce the cooling pattern when fed realistic meltwater volumes. However, this mechanism doesn't fully account for the near-total collapse of megafauna and human populations occurring simultaneously — that's where alternative hypotheses come in.
Meltwater hypothesis: mainstream explanation for Younger Dryas climate shift
Key facts
- The mainstream explanation involves Lake Agassiz, which was larger than all five modern Great Lakes combined
- An ice dam failed and drainage re-routed through the Mackenzie River Valley into the Arctic
- An enormous pulse of cold fresh water flooded into the North Atlantic
- Fresh water being lighter than salt water created a lid, stalling the Atlantic conveyor belt
- Without heat transport from ocean circulation, the northern hemisphere lost its main source of warmth
- Ocean sediment cores show the freshwater signal the theory predicts
- Climate models reproduce the cooling pattern when fed realistic meltwater volumes
- However, the hypothesis does not fully explain the near-total collapse of megafauna and Clovis people coincidence
Sources
Glacial Lake Agassiz: A 5000 yr history of change and its ...pubs.geoscienceworld.org
Lake Agassiz was the largest lake in North America during the last period of deglaciation; the lake extended over a total of 1.5 × 106 km2 ...
Glacial Lake Agassiz - North Dakota Geologic Surveydmr.nd.gov
Evidence of glacial Lake Agassiz occurs over an area of roughly 365,000 square miles, an area five times the size of the state of North Dakota, although at no ...
Lake Agassiz - Wikipediaen.wikipedia.org
Lakes of the Lake Agassiz basin ; Lake Winnipeg, 400 kilometres (250 miles), The southern area is 40 km (25 mi) wide. The northern area is 97 km (60 mi) wide.
The Legacy of Lake Agassiz - Conservation Corps Minnesota & Iowaconservationcorps.org
Its area surpassed all of our modern Great Lakes, combined. In fact, many of the major lakes in northern Minnesota and southern Manitoba are ...
North America's 6th Great Lake was larger than the other ... - AOL.comaol.com
Lake Agassiz no longer exists, however, it was one of the largest lakes in North America during the last ice age at an estimated size of around 170,000 ...
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