Phytoplankton plays a vital role in marine ecosystems. Apart from being a food source for marine animals, it removes carbon dioxide from the atmosphere through photosynthesis. Phytoplankton needs iron to grow. Whale poo is very rich in iron, containing 10 million times as much as seawater. Over the last century, commercial whaling has reduced the number of whales dramatically, starving the oceans of the necessary iron and decreasing the plankton’s capability to remove carbon dioxide from the atmosphere. Protecting whales and restoring their populations should therefore be an important goal for governments.