24.10.19

Whales Keep Carbon out of the Atmosphere

The world’s largest whales are more than mere evolutionary marvels. By sequestering carbon in the ocean, they can help humanity fight climate change—an ecosystem service that may be worth millions of dollars per whale, according to a new analysis by economists with the International Monetary Fund (IMF). Great whales, including the filter feeding baleen and sperm whales, help sequester carbon in a few ways. They hoard it in their fat and protein-rich bodies, stockpiling tons of carbon apiece like giant, swimming trees. When a whale dies and its carcass descends to the bottom of the sea, that stored carbon is taken out of the atmospheric cycle for hundreds to thousands of years, a literal carbon sink. A study estimated that eight types of baleen whales, including blue, humpback, and minke whales, collectively shuttle nearly 30,000 tons of carbon into the deep sea each year as their carcasses sink. If great whale populations rebounded to their pre-commercial whaling size, the authors estimate this carbon sink would increase by 160,000 tons a year. While they are alive, whales might do even more to capture carbon, thanks to their jumbo-sized excrement. Great whales feed on tiny marine organisms like plankton and krill in the ocean’s depths before surfacing to breathe, poop and pee—and the latter activities release enormous plume of nutrients, including nitrogen, phosphorus, and iron, into the water. So-called poo-namis stimulate the growth of phytoplankton, marine algae that pull carbon out of the air via photosynthesis.
Credit: Brut.