Simplify the following text for a Grade 10 native English-speaking person.
Original: The circulation could have been interrupted by the introduction of a large amount of fresh water to the North Atlantic , possibly caused by a period of warming before the Little Ice Age known as the Medieval Warm Period .
Simplified: The Gulf Stream could have been interrupted by the introduction of a large amount of fresh water to the North Atlantic , possibly caused by a period of warming before the little ice age .