Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks.
Answer:
Which one
Explanation:
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the lakes used to be covered in glaciers and when that averaged to about one kilometer thick, the glaciers moved towards canada and then it left behind big holes that filled with melted water, that became the great lakes.