Al said: "We're playing good rugby, have continuously improved during my four years at the club and I can see us continuing to do that."
He added: "Our fans are brilliant as well. They've continued to build year-on-year and that comes from success.
"We've built up a good team spirit and we work hard. That work ethic is massively important for me and the training facilities we will have next year are probably second to none in the Magners League."
Warriors head coach Sean Lineen said: "It's fantastic that Al has signed because it shows that he is committed to Glasgow. He is at the centre of everything that is good about Glasgow."