Whales could be a secret weapon in the battle against climate change

"Their size and longevity allow whales to exert strong effects on the carbon cycle."
Sade Agard
Whales play a huge role in the carbon cycle
Whales play a huge role in the carbon cycle

ALLVISIONN/iStock 

While many nature-based efforts to fight climate change have focused on solutions such as planting trees or restoring wetlands, researchers are now advocating for understanding the importance of carbon removal by the planet's largest animals – whales.

According to their study published today (Dec. 15) in Trends in Ecology and Evolution, the team examined how these marine giants can affect the quantity of carbon in our air and oceans. In doing so, they explored how whales potentially help to reduce atmospheric carbon dioxide. 

The greatest living carbon pools in the pelagic ocean

Led by Heidi Pearson- a biologist from the University of Alaska Southeast, the authors said in a press release, "Understanding the role of whales in the carbon cycle is a dynamic and emerging field that may benefit both marine conservation and climate-change strategies." 

"This will require interdisciplinary collaboration between marine ecologists, oceanographers, biogeochemists, carbon-cycle modelers, and economists," they added.

Whales can exceed the size of even giant airplanes, weigh up to 150 tonnes, and live for almost a century. Significantly, they make up one of the greatest living carbon pools in the pelagic ocean- a component of the marine system responsible for storing 22 percent of the carbon on Earth.

Like other living things, the substantial biomass of whales is mostly made of carbon.

"Their size and longevity allow whales to exert strong effects on the carbon cycle by storing carbon more effectively than small animals, ingesting extreme quantities of prey, and producing large volumes of waste products," explained the team. 

Rotting on the sea floor 

Whales could be a secret weapon in the battle against climate change
Whales’ direct and indirect nutrient and carbon cycling pathways

"Considering that baleen whales have some of the longest migrations on the planet, they potentially influence nutrient dynamics and carbon cycling over ocean-basin scales."

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Krill and photosynthetic plankton make up to 4 percent of the body weight of whales each day. For a blue whale, this is equivalent to roughly 8,000 pounds. 

When whales have finished digesting their food, their waste is nutrient-rich, enabling the krill and plankton to thrive and boost photosynthesis and atmospheric carbon sequestration (removal).

Using blue whales as an example again, these have a 90-year lifespan. The carbon they contain is transmitted to the deep sea as they rot after death on the seafloor. 

This process complements the biological carbon pump, which involves intricate biogeochemical pathways for the movement of nutrients and chemicals between the ocean and the atmosphere. 

Their full potential relies on conservation

Whale populations have declined by 81 percent due to commercial killing- the leading cause of population decline- with uncertain implications on the biological carbon cycle.

"Whale recovery has the potential for long-term self-sustained enhancement of the ocean carbon sink," the authors stated.

 "The full carbon dioxide reduction role of great whales (and other organisms) will only be realized through robust conservation and management interventions that directly promote population increases."

As Interesting Engineering previously reported, one unique concern about whales is that they are lower on the food chain than one might expect, given their massive size. This puts them closer to where plastic is in the water, and because they consume so much, they are ingesting up to 10 million microplastic pieces per day.

Most of the microplastics are coming from the creatures they consume- not from the seawater they gulp as they swoop for prey.

Therefore, interventions would at least need to include protecting whales and their prey from such human-induced pollution. After all, they're going to need the right nutrition to survive, right?