A whale´s fecal plume can stimulate the growth of phytoplankton in surface waters thereby fixing carbon and potentially helping to mitigate for climate change (Photo: A humpback whale produces a fecal plume before diving in Southeast Alaska. Copyright Heidi Pearson, taken under NMFS permit #10018-01).

Whales feed deep in the ocean and return to the surface to breath, digest, and, well… poo. The buoyant fecal plumes produced by whales are rich in nutrients such as iron, nitrogen, and phosphorus. These nutrients are exactly what phytoplankton need to grow and thus, importantly, absorb carbon dioxide in surface waters, allowing for more carbon to be naturally drawn into the oceans from the atmosphere.

The nutrients in whale poo and other by-products are also transported across oceans as whales migrate between high latitude feeding grounds and low latitude breeding grounds. This brings an influx of nutrients to otherwise nutrient-poor tropical waters. More nutrients mean more phytoplankton, which in turn absorb more carbon dioxide.

There are still other ways that whales can help trap carbon in the ocean. Through the force of their massive bodies swimming through the water, nutrients are stirred up and brought to phytoplankton. “In addition to being the largest animals on the planet, whales are among the longest-living, with some living over 150 years,” says Heidi Pearson, a marine biology professor at the University of Alaska Southeast and Fulbright Scholar at GRID-Arendal. This long lifespan means that a lot of carbon is trapped in a large whale for a long time. Then, once these animals die, their carcasses sink to the seafloor, bringing a lifetime of trapped carbon with them. Carbon on the seafloor is then essentially buried for thousands to millions of years. 

Whales and climate change were on the agenda today at GRID-Arendal, Norway. European ´climate action´ students visiting Norway though the International Children’s Press Centre were given presentations and participated in lively discussions on the subject. Dr. Heidi Pearson, a marine biology professor at the University of Alaska Southeast and Fulbright Scholar at GRID-Arendal, presented on the role whales and sea otters play in climate change mitigation. Steven Lutz, Blue Carbon Programme Leader at GRID-Arendal, presented on coastal and marine ecosystems in international policy, both for whale conservation and climate change action. 

“More whales means more carbon trapped, making whale conservation a potentially exciting new strategy for climate change mitigation,” says Pearson. This idea is starting to catch on. At the 2016 IWC meeting, a resolution was passed that recognized the role of whales in trapping carbon dioxide and creating healthy ecosystems. Healthy ecosystems are not only important for the climate but for safe-guarding fisheries and other vital ocean resources. At the 2017 UN Ocean Conference, the Oceanic Blue Carbon Voluntary Commitment was introduced to draw attention to the role of whales and other marine life in combatting climate change. This Commitment was endorsed by over 100 organizations and members of the scientific community. 

Whales and climate change will again be on the agenda at next week’s meeting of the IWC in Brazil where representatives of the 88 member nations will vote on resolutions related to whale conservation and management. These include a resolution submitted by Chile that encourages governments to recognize and integrate the ecological values of whales and dolphins “into local, regional and global decision-making on the environment, including climate change and conservation policies.” However, this resolution is reportedly opposed by Japan which is leading a push to resume commercial whaling. 

“Endorsement of this resolution will both recognize the importance of whales in mitigating climate change and help to ensure that populations increase to pre-whaling levels,” says Steven Lutz, Blue Carbon Programme Leader at GRID-Arendal. “Recognition of whales as our partners in the fight against global climate change is also potentially applicable to many other policies and conventions, including how countries recognize the ocean in their pledges to fulfill the Paris Climate Agreement.”

*Heidi Pearson was a Fulbright Scholar working at GRID-Arendal in 2018.

Sources: 

Lavery TJ, et al. 2012. Can whales mix the ocean? Biogeosciences Discussions 9: 8387-8403. 

Lutz and Martin. 2014. Fish Carbon, Exploring Marine Vertebrate Carbon Services. Report. GRID-Arendal, Norway.

Roman J, et al. 2014. Whales as marine ecosystem engineers. Frontiers in Ecology and the Environment 12: 377-385.

Shanahan M. 2018. How whale poop could counter calls to resume commercial hunting. Scientific American. August 28, 2018.

GRID-Arendal. 2016. Save a Whale, Save the Planet. Blog post. GRID-Arendal, Norway.