Final answer:
Melting of the Greenland ice sheet could disrupt the formation of North Atlantic deep water, leading to colder temperatures in northern Europe and North America. Hence, the correct answer is option D.
Step-by-step explanation:
The warming of the earth's climate and the resulting melting of the Greenland ice sheet could disrupt the formation of North Atlantic deep water. This disruption could lead to colder temperatures in northern Europe and North America. The North Atlantic deep water plays a critical role in driving the Gulf Stream, which warms these regions. If the formation of this deep water is impeded, the heat transfer to northern latitudes will decrease, making these areas colder despite the overall global warming.