Sea Otters To Combat Climate Change?

Does a large population of sea otters reverse one of the principal causes of climate change? New research from the UC Santa Cruz is suggesting that a population boom of sea otters would go a long way to reduce sea urchin numbers, and therefore allow kelp forests to become very large.

“The spreading kelp can absorb as much as 12 times the amount of CO2 from the atmosphere than if it were subject to ravenous sea urchins, the study finds.” Of course, altering a food chain so significantly could have unintended consequences.


The theory was just outlined in a paper published September 7 in the journal Frontiers in Ecology and the Environment.

“It is significant because it shows that animals can have a big influence on the carbon cycle,” said Wilmers, assistant professor of environmental studies.

“Wilmers, Estes, a professor of ecology and evolutionary biology, and their co-authors, combined 40 years of data on otters and kelp bloom from Vancouver Island to the western edge of Alaska’s Aleutian Islands. They found that otters ‘undoubtedly’ have a strong influence on the cycle of CO2 storage.”

“Comparing kelp density with otters and kelp density without otters, they found that ‘sea otters have a positive indirect effect on kelp biomass by preying on sea urchins, a kelp grazer.’ When otters are around, sea urchins hide in crevices and eat kelp scraps. With no otters around, sea urchins graze voraciously on living kelp.”

“Kelp is particularly efficient at sequestering CO2 from the atmosphere through photosynthesis. CO2 concentration in the atmosphere has increased 40 percent since the beginning of the industrial revolution, causing global temperatures to rise, the authors write.”

“Wilmers and Estes acknowledge that a spreading otter population won’t solve the problem of higher CO2 in the atmosphere but argue that the restoration and protection of otters is an example how managing animal populations can affect ecosystems abilities to sequester carbon.”

“Right now, all the climate change models and proposed methods of sequestering carbon ignore animals,” Wilmers said. “But animals the world over, working in different ways to influence the carbon cycle, might actually have a large impact.”

“If ecologists can get a better handle on what these impacts are, there might be opportunities for win-win conservation scenarios, whereby animal species are protected or enhanced, and carbon gets sequestered,” he said.

“Mitigating increased CO2 in the atmosphere is a pressing issue in global environmental conservation with many obstacles and no easy solutions, the authors write. They note that markets have been established in Europe and the United States to trade carbon credits and thus inject an economic incentive into either reducing CO2 output or increasing CO2 sequestration.”

“They estimate that the CO2 removed from the atmosphere via the otter-kelp link could be worth between $205 million and $408 million on the European Carbon Exchange.”

“An alluring idea,” they write, would be to sell the carbon indirectly sequestered by the sea otter protected kelp forest “as a way to pay for their reintroduction and management or to compensate losses to shell fisheries from sea otter predation.”

Source: University of California – Santa Cruz
Image Credits: Arthur Morris; Chris Brown/USGS

76 thoughts on “Sea Otters To Combat Climate Change?”

  1. Now you know the rest of the story. LLoyd Bridges died on the TV hit series, Sea Hunt, from being tangled up in a kelp bed caused by rising CO2 levels.

  2. Over the last ten years the urchins showed up on my beach in costa rica, snuggling into dips in the many piles of rocks seemingly made for or by them, but volcanic rocks are full of holes so it seems more likely that they found them. The urchins seemed to eat every green seaweed in the tide pools, many little fish disappeared as well. Then, as suddenly as they appeared, they left. This year I didn’t see any, while there were hundreds in previous years. I assume they ate themselves out of house and home. They don’t seem to have any enemies down there, not ocean mammals at any rate.

  3. The principal food of otters is not sea urchins, they eat many other shellfish and small fishes. Sea urchins are just opportunistic eating. At no point did these scientists say “IF WE DO THIS WE CAN EMIT INCREASING AMOUNTS OF CO2 FOREVER”, they said this was a possible and economical carbon sequestration scheme that didn’t require vast investments. My biggest gripe with amateur “ecologists” is this tendency to read things that nobody said.

  4. How about this scheme: Feed the cats to the rats and the rats to the cats and get the skins for nothing. Or pull yourself up by your bootstraps. Do what you want but count me out! I pass!

  5. Urchin gonads are unbelieveably delicious – buttery and creamy with an umami hit that can only be experienced, not described.
    Why should sea otters have all the fun – harvest the urchins and send some of that uni my way. MMmmmmmm……

  6. The proposition is preposterous. What you’re describing is the ongoing continuation of CO2 and methane emissions at the current unsustainable high numbers, with kelp sucking up the titanic amounts of greenhouse gases. The greenhouse gases need to stop in conjunction with potential small solutions like more kelp.

  7. If you want to reduce CO2 levels in the atmosphere, just cool the ocean a few degrees and atmospheric CO2 will drop. Warm it and CO2 will rise. These magic CO2 “global warming” pseudoscience peddling quacks can’t understand cause and effect.

  8. Any CO2 that is in the environment is going to stay in the environment–if it spends a brief time as part of a kelp plant, as soon as the kelp dies it will turn right back into CO2–if a sea urchin eats the kelp its waste products will decompose into CO2–just as if the kelp had died a natural death–the idea that trees and other plants remove CO2 totally overlooks the fact that plants aren’t immortal, and upon death revert to CO2 and water (which happens to be 10 times as powerful a greenhouse gas as CO2–taking into account that there is much more water vapor in the atmosphere than CO2 water vapor actually ends up exerting over 600 times the affect on temperature as CO2.

  9. In 1970 I participated in a kill the urchins project in San Pedro. They had decimated the kelp forest there to such an extent that it was completely gone. There is a heathy kelp forest there now. Why do we have to learn these lessons over and over?

    1. I agree….”will they never learn?” However, they keep getting paid to do the studies -over & over… who’s expense? What about the livihood of the sea Urchin divers ? Who will save their jobs ?

  10. MadCity Observer

    If otter populations are “managed” by increasing their population at the expense of the sea urchin population, then after just a little while and the sea urchin population declines then what will all those additional otters eat? All in all it seems to me this idea isn’t without the risk of unintended consequences.

  11. Climate change solved by otters eating sea urchins? How much methane does that put in the atmosphere? Methane is significantly more destructive in global warming then CO2.
    The damage is done. We cannot stop it any more. Just a matter of time now before economies and societies collapse, and Mad Max moves from fiction to prophesy! LOL

  12. Nice, but pie in the sky. Your headline is misleading. Once the otters run out of urchins, they eat a wide range of other prey, and finally starve back to a supportable population. Otters will not save us from our indusrial folly. We are going to have to die back to a supportable population too.

  13. Better yet, harvest the sea urchins directly! Uni fetch high prices at a sushi table. Boost the economy and the ecology in one swell foop….

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