The earth naturally has an ebb and flow. I live in the middle of South Carolina, about 2 hours from the shore and yet where I live was once beechfront property. Fossils of shells and sand are common here.
I think it would be ignorant to believe that sea levels won't change again. I do believe that in the grand scheme of things, humans are not mighty enough to destroy the earth. She is much older and more resiliant than we are. The earth will heal herself of what we do. If (when) there is another ice age, our population will decrease but survive and then we will have another go at it. Hopefully next time we will take better care.

Bike to the beach, hop on your sail boat, bike to the mountains and run a river in a kayak (yes, you can tow one behind a bike). Both you and the earth will be in better shape!