A Climate Engineering Solution I Can Get Behind: Whales as (Literal) Carbon Sink
Problem: There’s too much carbon dioxide in the air.
One Solution: Put it somewhere else.
Sub-solution: Whales?
I mean, whales are huge! We’re talking about a mammal the size of an airplane. Tons of carbon get sucked out of the air (and ocean) to feed and grow even one whale, so each one is a blubbery, singing carbon sink. Given that they have human lifespans, and that when they die (or poop … let’s not forget about the whale-sized quantities of poop) that matter heads straight for Davy Jones’s locker, where it tends to remain and get locked in the sediments of carbon prison, it seems like a solid proposition of unknown quantitative value.
This bold idea is studied in detail in a new opinion piece in Trends in Ecology and Evolution, where the authors argue this is a low-regrets solution that we should be working on. This is exactly the sort of bold, innovative climate thinking we need, because it is demonstrable that a) we have too much carbon in the air and b) we do not have enough whales in the water. Win-win!
Please enjoy this delightful and helpful graphic from the piece, demonstrating what we might term a virtuous fecal cycle. It showcases whales’ talents as scatological catalysts of carbon storage:
As you can see, whales trap carbon in several ways. First, each whale possesses a massive, highly efficient, long-lived body. Although it’s true the krill that could feed one great whale can be consumed by many more smaller organisms, due to whales’ massive economy of scale, the amount of carbon stored by the smaller animals collectively is smaller. One study calculated that the amount of krill that supported one 92-ton blue whale would support seven minke whales or 1,800 Adelie penguins, but that the minkes would only have 50% of the biomass of the blue while the penguins would replace just 8%.
Next, when they die, whalefalls inject carbon directly into the seabed or into communities of animals where it is likely to stay trapped by stagnant water, beneath the maximum annual mixed layer depth.
Third, given that whales ingest what the authors themselves term “extreme” quantities of prey, the inevitable result is “extreme” quantities of something else that serves as plankton fertilizer and food (and in case you’ve ever wondered what it’s like, here you go.)
Whale poo seems to favor the growth of heavier plankton like krill (itself whale food) and glass-shelled diatoms that are more likely to sink quickly when they die. These organisms also migrate daily between the surface and the deep, which puts the carbon that much closer to prison when they happen to do their business or die at depth. Is there actual evidence for this indirect effect? Scientists have observed that ecosystem productivity has declined in areas with depleted whale populations like the Southern Ocean.
Then we have the “Great Whale Conveyor Belt”, which on first impression strikes me as being like one of those sushi trains driving your lunch around except in this case for krill headed baleen-ward. In actuality it refers to the fact that Pacific whales do much of their nomming in Alaska and the Aleutians before returning to Hawaii to breed, give birth, and, you know, scuttle the ballast. That ballast includes not just the usual Number One and Number Two but also things like whale placentas (did you ever stop to think about the fact that whale placentas exist before? I didn’t.) and sloughed skin. Whales may die here too. While they’re in Hawaii, the whales usually don’t eat and subsist entirely on blubber (and that includes making milk by nursing mothers(!)).
The oceans excel at trapping carbon, but they are best at doing so at high latititudes and near shore. Although they seem like paradise to humans, the waters around remote tropical islands can be a bit like food deserts to the animals that live theere. All this whale junk is a veritable windfall for them, pumped in from the rich waters of Alaska and now available to the deserving but undernourished biota of Hawaii, boosting numbers of fish, scavengers and invertebrates in the process.
OK, just how many potential future whales are we talking here, you may ask? Excellent question. As it turns out, there happens to be a lot of proven room in the ocean for more whales. In the last 300 years, the human appetite for whales was so voracious that, by one estimate, the volume of whale flesh on the planet declined by 81%. To give you a sense of what that means in real numbers, in 1900 (after a century of large-scale whaling, but with so much more to come) there are estimated to have been 762,400 fin whales. By 2001, that number was 109,600. For blue whales, the numbers are 340,280 to 4,727.
One blue whale is about the size of two school busses end-to-end (or two T. rexes similarly arrayed), and they are but one of almost a dozen large whale species that were hunted and decimated. Doing the math, scientists estimate the oceans are missing 17,000,000 tons of carbon that used to be whale or organisms supported by whales but is now mostly floating around in the atmosphere. That’s one hell of an underused carbon storage facility.
Considering also that these whales live far longer than most ocean life, on the order of our lifespans or even longer (Arctic bowhead whales can live over 200 years), they constitute one of the largest and most stable carbon pools of open ocean. Current estimates indicate that whales are storing, sequestering, and exporting carbon on the order of hundreds of thousands to millions of tons a year, and could be doing so by at least an order of magnitude more if their numbers were restored to historic levels.
Yet it’s a thing that’s much easier said than done. Although some whales have mounted stunning recoveries, many species’ numbers are still falling or stagnant. While whales face many intractible unique obstacles to recovery, one big one they all share is this: their reproduction is slow. We can’t get around that biological constraint, but we could all look into doing more.
It’s almost poetic (ironic?) that the same thing that saved sperm whales from American whalers at the end of the 19th century — cheap petroleum, which began to fuel lamps instead of whale oil — is also the same thing that is also today precipitating our climate crisis, and yet might itself be converted back into whale form.
I also want to send a hearty thanks to the authors of this paper and to Trends in Ecology and Evolution for publishing this important perspective, because it does actually make a great point. Blue and fin whales are the biggest animals EVER to evolve (including dinosaurs, folks!) and we should be doing absolutely everything we can to make more of them. And, I mean, climate crisis aside, how can you not want more of these things on your planet? It reminds me of what Apollo 11 astronaut Michael Collins said upon splashing down in the technicolor Pacific after just over a week of space and moon monochrome: “Nice ocean you’ve got here, Planet Earth”. We’ve got a bona fide miracle going on this pale blue dot. Let’s make it even better.