Try telling people that our sun will disappear as a white dwarf in 8 billion years BUT after 100,000 years it will expand in size sufficiently to make life on Earth impossible. If you suggest to people that human technology may find a way to extend human existence by altering the Earth's orbit and then by sending out ships manned by self repairing robots with all of earths life and knowledge digitized and frozen (like a Noah's ark) seeking a habitable planet.... why people will LAUGH at you and say that they do not care because they will get to live out their miserable little lives eating, drinking, sleeping, cheating one another and they could care less what happens in 100,000 years ... so the bottom line is that no one gives a darn... 

Same with Venice, which is crumbling by the action of the sea. Engineers have devised a plan to save Venice but it would take 30 years and no miserable politician has a term of more than 6 years so no politician would make and effort to implement that plan because it would not personally advance their own self-serving career. So, let Venice crumble and let human culture go to blazes just so long as I get to live out my own selfish little existence of 80 years.