Nature-based solutions to combat climate change take a holistic approach that promotes biodiversity and ecosystem preservation. While many efforts have focused on planting trees or restoring wetlands, researchers publishing in Trends in Ecology and Evolution on Dec. 15 argue for the importance of understanding the carbon sequestration potential of the planet’s largest animals : the whales In their paper, the researchers explore how these marine giants can influence the amount of carbon in our air and waters and potentially contribute to the global reduction of atmospheric carbon dioxide.
“Understanding the role of whales in the carbon cycle is a dynamic and emerging field that can benefit both marine conservation and climate change strategies,” write the authors, led by University of Alaska Southern biologist Heidi Pearson -East. “This will require interdisciplinary collaboration between marine ecologists, oceanographers, biogeochemists, carbon cycle modelers and economists.”
Whales can weigh up to 150 tons, live more than 100 years, and be the size of large airplanes. Like all living things, their large biomass is composed primarily of carbon, and they constitute one of the largest pools of living carbon in the pelagic ocean, part of the marine system that is responsible for storing 22% of the total carbon in the world. land
“Their size and longevity allow whales to exert strong effects on the carbon cycle by storing carbon more effectively than small animals, ingesting extreme amounts of prey, and producing large volumes of waste,” the authors write. “Given that baleen whales have some of the longest migrations on the planet, they can influence nutrient dynamics and carbon cycling at ocean basin scales.”
Whales consume up to 4% of their mass body weight in krill and photosynthetic plankton each day. For the blue whale, that equates to nearly 8,000 pounds. When they finish digesting their food, their excrement is rich in important nutrients that help these krill and plankton bloom, helping to increase photosynthesis and atmospheric carbon storage.
A blue whale can live up to 90 years. When they die and their bodies fall to the seafloor, the carbon they contain is transferred to the deep sea as they decompose. This complements the biological carbon pump, where nutrients and chemicals are exchanged between the ocean and atmosphere through complex biogeochemical pathways. Commercial hunting, the main source of population decline, has reduced whale populations by 81%, with unknown effects on the biological carbon bomb.
“Whale recovery has the potential for long-term self-sustaining enhancement of the ocean’s carbon pool,” the authors write. “The full carbon dioxide-reducing role of large whales (and other organisms) will only be realized through robust conservation and management interventions that directly promote population growth.”
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