Let's load up an old cargo ship and invite them to a coral reef cruise. Tell them they would be helping the eviornment by seeding a new coral reef. Sink the ship there with everyone on board. Think of the good the people would be participating in as the sea welcomed the growth and nutrition of liberals and their artificial structure.
Someday (assuming the whole globul warming thing has been "conquered") in about 250 years, those liberal's great, great, great grandkids will be able to visit that reef and tell their liberal children kids their ancestors created life in the ocean and thereby all the life on earth.
I like that!