If the Oceans Die will we run out of Oxygen? Some say yes. The world’s oceans are also known as the lungs of our planet. As much as 70% of the world’s Oxygen comes from tiny plants called phytoplankton. Sadly since the 1950 there has been a 40% decline in their numbers. Besides supplying most of the OxygenOxygen we humans breath phytoplankton also provides food for most of the ocean’s creatures. So while I can’t answer the question definitely, if there is even a chance that if the world’s ocean’s die we lose 70% of the Oxygen we breathe, is it worth taking the chance?