Whales help mitigate climate change by pooping carbon into the ocean and taking more with them when they die, scientists say

• Whales are the biggest animals on Earth and their huge bodies play a role in the carbon cycle.
• They capture carbon in their body as they live and encourage biodiversity with their poop.

Whales naturally help divert carbon away from the atmosphere in life and death, scientists said in a review published Thursday.

Because they are so large — with the largest whales bigger even than the dinosaurs — the amount of carbon they capture throughout their lifetime is substantial.

Though it may not be a solution to the climate crisis on its own, their ability to store carbon is another reason to encourage their numbers to rise in the oceans, the scientists said.

The results of their analysis were published in the peer-reviewed journal Trends in Ecology and Evolution.

Whales naturally store carbon by living their life

Whales capture carbon mainly by pooping and dying. The diagram below explains how.

Any animal, big or small, is part of a carbon cycle. Carbon is present in every lifeform on Earth. Animals get carbon by eating plants and animal products, and plants get it from the atmosphere.

That carbon is either stored in the body until the animal's death or shed as feces. These byproducts are then nibbled on by other animals and plants, putting that carbon back into the food chain.

When you're as big as a whale, what happens to your body and your poop can have a huge effect.

"Because whales are so large, they have the potential to store vast amounts of carbon," said Heidi Pearson, a study author and biologist from the University of Alaska Southeast, in an interview with Insider.

Whales weigh up to 150 tons and can live more than 100 years. That's a lot of carbon stored in their body, away from the atmosphere, until they die.

"You can think of whales as like big floating trees in the ocean," Pearson said.

Eating, pooping, and peeing the ecosystem back to life

What they don't store in their body, the whales poop and pee back into the ocean.

Previous studies have shown that this is incredibly important for the ecosystem. When whale populations dropped after the widespread whaling of the 1900s, plankton populations counterintuitively plummeted as well.

That is because plankton feeds on whale poop, so the disappearance of even one whale causes a huge deficit in the ocean ecosystem. This is called the whale pump effect.

By encouraging new life, the whales are creating more organisms that can capture carbon away from the atmosphere.

The whales can then feed on these new lifeforms, in huge quantities, locking that carbon in their body for many decades.

Finally, when they die, the whales' bodies tend to sink all the way down to the bottom of the ocean, where the carbon stays out of the atmosphere.

"It's going to remain out of contact with the atmosphere for hundreds, thousands of years, maybe even longer. And whales do this naturally," Pearson said.

Not a silver bullet

By encouraging whale numbers to grow, their carbon-locking effect can be amplified.

"We feel it's worth conserving whales for many reasons. They're important components of healthy ecosystems and they help to promote biodiversity, given that we are also in a biodiversity crisis," Pearson said.

"This potential climate benefit is just another reason," she said.

Conservation today is less about whaling and more about creating protected areas in the ocean to avoid collisions with ships, keeping the oceans quiet, and avoiding whales getting tangled in fishing gear, Pearson said.

"Another big thing is climate change. So it kind of goes full circle," she said.

Pearson warned, however, that she doesn't think it should be seen as a viable solution to the climate crisis on its own.

Advocates of nature-based solutions suggest that by bringing back biodiversity, for instance by planting trees and encouraging re-wilding, a substantial amount of the excess carbon in the atmosphere could be captured in living organisms.

This is true, and this approach has obvious positive knock-on benefits for the environment, but it's not the full story.

Estimates suggest that nature-based solutions can provide 37% of the climate change mitigation by 2030 that is needed to meet the goal of keeping climate warming below 2 degrees Celsius, according to the World Bank.

"They're not the silver bullet. Even if we could really get strong conservation measures and recover whale populations to their pre-industrial whaling abundance, that's still not gonna solve the climate crisis," she said.

"It's gonna be one small piece of everything we need to do," she said.