Great whales contribute US$1 trillion to fight climate change, says IMF

A FASCINATING IMF ecosystems services study concludes that whales absorb more carbon than the rainforests and help to produce more than half the world’s oxygen supply, making a powerful case for protecting and increasing populations of these giant deepsea mammals.   

Increasing the global whale population offers “a low-tech solution” to global warming, capturing and storing carbon in the deep, it says. “When it comes to saving the planet, one whale is worth thousands of trees… Our conservative estimates put the value of the average great whale, based on its various activities, at more than US$2 million, and easily over US$1 trillion for the current stock of great whales.”

The study draws on new research from marine biologists, showing that the great whales play a key role in capturing carbon from the atmosphere. It says better understanding of the role whales play in limiting greenhouse gases and slowing global warming could support more investment in conserving them, as a nature-based solution.

“The carbon capture potential of whales is truly startling,” say authors Ralph Chami, Thomas Cosimano, Connel Fullenkamp and Sena Oztosun. “Whales accumulate carbon in their bodies during their long lives.

“When they die, they sink to the bottom of the ocean: each great whale sequesters 33 tonnes of CO2 on average, taking that carbon out of the atmosphere for centuries. A tree, meanwhile, absorbs only up to 48 lbs of CO2 a year.”

Whale poo contains vital nutrients to support growth in phytoplankton, including nitrogen and iron. Whales bring minerals to the ocean surface in two ways; through their vertical movements and as they migrate across oceans. Preliminary modelling and estimates indicate that both activities support phytoplankton growth in areas that whales frequent.

That works to slow global warming, because phytoplankton contribute to at least half the oxygen in our atmosphere and capture about 37 billion tonnes of CO2, an estimated 40 per cent of all the CO2 produced.

“If whales were allowed to return to their pre-whaling number of four to five million, from slightly more than 1.3 million today, it could add significantly to the amount of phytoplankton in the oceans and to the carbon they capture each year,” it says.

“At a minimum, even a 1 per cent increase in phytoplankton productivity thanks to whale activity would capture hundreds of millions of tonnes of additional CO2 a year, equivalent to the sudden appearance of two billion mature trees. Imagine the impact over the average lifespan of a whale, more than 60 years.”

However, populations of the largest great whales have declined to a fraction of former numbers, despite widespread restrictions on hunting whales for their oil and as food. Whales face a continued threat from marine and noise pollution, deepsea mining and fishing and ship strikes.

“Some species, like the blue whales, have been reduced to only 3 per cent of their previous abundance,” the IMF says. “Thus, the benefits from whales’ ecosystem services to us and to our survival are much less than they could be.”

International efforts to restore whale populations could lead to a breakthrough in the fight against climate change, the report says. But what would that cost?

“We estimate that, if whales were allowed to return to their pre-whaling numbers, capturing 1.7 billion tons of CO2 annually, it would be worth about US$13 per person a year to subsidise these whales’ CO2 sequestration efforts,” the IMF concludes.

Is it ethical to value these powerful, gentle giants for their benefits, not on their own terms? Responding, Ralph Chami tells The Environment: “To influence, you need to know your audience. For my audience, [that’s] what’s in it for me. I had to say, even if you don’t care for the whales’ intrinsic beauty and value, you ought to care for them for what they do for you.”

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