Why whales could promote carbon storage

Blue whales, fin whales and sperm whales are among the largest creatures on earth. The giants, which weigh several tons, could possibly help in the fight against climate change, writes a team of US researchers in the journal Trends in Ecology

In their contribution, the researchers led by Heidi Pearson from the University of Alaska Southeast explain the role that large whales play in the oceans for the earth's carbon cycle. Whales eat up to four percent of their own body mass in the form of krill and plankton - every day. They store the carbon that makes up most of their food in their own biomass. On the other hand, their nutrient-rich excretions encourage the growth of phytoplankton, which in turn sequesters carbon dioxide from the atmosphere.

Because of their size and longevity, whales store carbon more effectively than small animals, consume excessive amounts of prey, and produce large amounts of waste products. "Considering that baleen whales have some of the longest migrations on the planet, they may be affecting nutrient dynamics and carbon cycling across ocean basins."

With industrial whaling and the shrinking of many whale populations, the amount of carbon stored in the animals has decreased, the researchers write.

The authors are not able to say unequivocally whether measures to protect and recover stocks could actually be a nature-based solution in the fight against climate change. There is still too little data and too many uncertainties to be able to estimate the potential quantitatively.

But: "Natural amplification of the oceanic carbon sink through the protection of whales could be an effective strategy for removing carbon dioxide with low risk, longer durability and higher efficiency than geoengineering solutions, such as direct carbon injection into the interior of the ocean."

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