NEW ORLEANS -- Mayor Mitch Landrieu on Friday unveiled plans he said will ensure New Orleans plays its part in combating climate change.

Speaking on the roof of the Sewerage & Water Board's Warehouse District where he showed off the utility's new "green roof," Landrieu said that the city might not exist in the next 300 years if action is not taken.

Landrieu signed an executive order that features four points aimed at fighting climate change: modernizing energy use, improving transportation choices, reducing waste and creating a culture of awareness and action.

"It is abundantly clear that climate change is a matter of life and death," Landrieu said.

Landrieu said a study from the National Academy of Science notes the sea level in New Orleans is expected to rise to about 6.5 feet by 2100. The study said average temperatures are expected to climb as well.

"We have coastal erosion happening before our eyes, and we have sea level rise,” Landrieu said. “That means it's an existential threat if don't do anything to protect ourselves."