Answer: Phytoplankton and the single-celled variety that krill eat are responsible for absorbing a massive amount of carbon from the atmosphere. In the absence of whales, krill would likely eat much of the free-floating phytoplankton on the ocean's surface, resulting in a marked acceleration in climate change.
Explanation:
Humans selectively fish out the largest species from Earth's oceans, causing their populations to dwindle. If that weren't alarming enough, the extinction of those animals—think a great white shark, bluefin tuna, and blue whale—could ripple down the food chain and spell extinction for entire ecosystems.