According to the passage, which of the following is true about the sea ice that surrounds the Antarctic continent? A. The amount of sea ice that forms in the winter has been declining. B. Most of the sea ice that forms in the winter remains intact in the summer. C. Even small changes in the amount of sea ice dramatically affect the temperature of the surface waters. D. Changes in the amount of sea ice due to global warming would significantly affect the stability of the Antarctic environment. E. Changes in the amount of sea ice affect the degree of saltiness of the surface waters.