why is the statue of liberty green?

Copper develops a green patina. You'll see it on many buildings with copper domes or trim.

Green is the colour of all those movements which want to reduce global warming.

Because it's sheathed in Copper to protect it

The Statue of Liberty is coated with a thin layer of copper, which turns a blue-green with age due to chemical reactions between metal and water. This process is known as patination and occurs with most copper when it’s placed outside.

The true color of the Statue of Liberty before patination was a shiny reddish brown color. The photo to the right shows a replica of the statue and what the Statue of Liberty’s original color would look like.

Some interesting info relating to that. When iron or steel rusts over time it creates flakes of rust - oxide. Those fall off and expose fresh metal underneath and it all happens again. And eventually the iron or steel just rusts away to nothing, which is why it's such a big problem in things like bridges and anything steel.Most other metals don't do that and the oxide layer stays put and protects the metal underneath. So yes, the green layer protects the metal underneath. We could clean it off, which would expose more copper, which would corrode, and over and over until the statue is gone. As it is it just sits there just fine. Aluminum oxidizes almost immediately upon exposure and it is a tough layer. If not for that we couldn't have aluminum things in life. The patina on Liberty protects it almost as well as a coat of paint would.

Copper oxidizes green, just as iron rusts red/brown. What do you suppose Lady Liberty is made of?

cause whoever made it painted it that way

Copper tarnish.

They should clean it some time.

It's copper, which over time takes on a green appearance.  When the statue was initially crafted and placed in New York Harbor, it had a copper appearance.

In theory, the statue could be restored to its initial copper appearance, but in addition to being very difficult and expensive to restore, the process of turning green would only start over again.  Too much cleaning would damage the statue.   So, the decision was made to leave it green.

That’s how copper looks when it gets old and it oxidizes. It used to be bright and shiny like a shiny new penny.