Great whales, the largest creatures in the sea, can help mitigate climate change by locking up carbon in their massive bodies and boosting phytoplankton with their waste products.
A preliminary study
by researchers with the International Monetary Fund’s Institute for Capacity Development, the University of Notre Dame, and Duke University found that each great whale sequesters an average of 33 tons of CO2 over its lifetime, taking that carbon out of the atmosphere for centuries: when a whale dies and sinks to the sea floor, it takes that carbon with it, says Joe Roman, conservation biologist and author of Whale
. (Compare that to a tree, which sequesters about 48 pounds of CO2 per year.) Whales act as nutrient pumps in the ocean as they dive and feed and then surface, nourishing phytoplankton growth with their waste products, which contain the iron and nitrogen the marine algae need to grow. This in turn increases carbon sequestration: phytoplankton capture about 37 billion metric tons of CO2 a year, an estimated 40 percent of all CO2 produced. Whales also act like nutrient “conveyor belts” by distributing more fertilizer for phytoplankton in their fecal plumes when they migrate from feeding grounds to breeding grounds, which are often nutrient-poor. “Whales can’t stop climate change, that’s up to us,” says Roman. "But we can use natural systems like whales in the sea and trees on land to help reduce some of the impacts.” Although the current population of many of the great whales is only a fraction of what it was prior to industrial whaling, some whale populations have come roaring back in just a few decades, says Roman. The bounceback is thanks to legal protections like the Marine Mammal Protection Act and moratoriums on hunting. And despite the myriad threats whales face—fishing line entanglement, pollution, ship strikes, among others—management techniques like changing shipping lane patterns have proven very effective in protecting whales like humpbacks.