How can I convence my dad to quit smoking?

He has a bunch of things wrong with him, medically. And yesterday he was diagnosed with Chronic Obstructive Pulmonary Disease. He won't listen to me or my brothers about quitting. His life expectancy was 7-9 years about 6 years ago...now with the COPD it's cut even shorter. How can I convince him to quit or slow down at the least?? He has 6 grand children and he is 53.