Can farmed seaweed help reverse the effects of climate change?

Could farmed seaweed—used in food, animal feed, cosmetics, and fertilizer—help reverse the effects of climate change? To find out, researchers are using a collection of custom sensors that measure the carbon capture potential of kelp farming, an industry that benefits marine ecosystems, reinvigorates local economies, and may mitigate global carbon emissions.

Diagram of kelp farming process© WWF-US/MATT TWOMBLY
  1. Carbon dioxide
    The ocean absorbs 25% of CO2 in the atmosphere.
  2. Sunlight
  3. Photosynthesis
  4. Oxygen
  5. Carbon
  1. The parts

    Cage Protects the sensors and orients them close together at the depth of the growing kelp, ensuring they measure the same water

    Self-calibrating SeapHOx sensors Measure seawater salinity, temperature, depth, pH, and oxygen—data that help determine the rate of ocean acidification

    Additional sensors Measure partial pressure of CO2 and light

  1. Ocean acidification
    Ocean acidification occurs when the ocean takes up excess CO2 from the atmosphere, causing chemical reactions that produce carbonic acid and lower seawater’s pH. As acidity rises, calcium carbonate becomes less abundant, threatening corals, clams, oysters, and other sea life that rely on it to grow strong skeletons and shells.

    Mussels grown within seaweed farms appear to grow thicker, healthier shells.
  2. Climate hero
    When kelp is farmed and harvested, small fragments naturally break off and can be buried on the seafloor, where the carbon the kelp absorbs is potentially locked away for centuries.

Algal advantages

Like plants, seaweed absorbs CO2 and various nutrients and releases oxygen as it grows. This process benefits the climate and improves water quality and may also create a “halo effect”—an area of lower ocean acidity that helps shell-forming species in the surrounding waters thrive.

Studying seaweed

Since 2021, researchers from the Bigelow Laboratory for Ocean Sciences and WWF have deployed oceanographic instruments to study kelp’s capacity to minimize the impacts of climate change at aquaculture sites in Alaska, Maine, and Norway. Their aim: to better understand the size and efficacy of the halo effect as well as its consistency across different kelp species, farms, and oceanic conditions.

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