This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Climate change is driving rapid declines in seaweed forests globally, outpacing restoration efforts and undermining seaweed restoration as a viable carbon dioxide removal strategy, according to an essay by Karen Filbee-Dexter at the University of Western Australia and colleagues, published Sept. 8 in the journal PLOS Biology. Natural ecosystems have played an important role in mitigating greenhouse gas emissions over the last century by absorbing carbon dioxide from the atmosphere, but climate change itself is jeopardizing this vital ecosystem service.
Planting and restoring seaweed forests is often promoted as a natural climate solution because of their ability to sequester carbon and store it in the deep ocean. However, global declines in seaweed forests threaten to undermine restoration efforts. Researchers analyzed published data on global seaweed forest gains and losses to estimate the net effect on carbon sequestration.
They found that declines in kelp forests—the most widespread and productive seaweed ecosystem—could result in a reduction in natural carbon sequestration of 1.5 million to 30 million tons per year. This loss is between 1,000 and 10,000 times greater than the gain in annual carbon dioxide sequestration from kelp forest restoration projects to date. An estimated 25 million hectares of wild kelp forests will be lost by 2050 because of climate change—more than 6,000 times the area that has been restored since 1958.
Large-scale kelp restoration projects in Norway and California required huge investments of time, money and effort. Tens of thousands more projects like these would be needed to compensate for climate change-driven kelp forest losses, at a cost of tens or even hundreds of billions of U.S. dollars. Carbon sequestration by natural ecosystems has been so reliable that it has been implicitly embedded in climate projections and net-zero planning, but climate change is now compromising those natural services.
The authors conclude that the current focus on seaweed forest restoration as a natural climate solution could distract conservationists from protecting threatened seaweed habitats, even though preventing habitat loss is a cheaper and more effective climate change mitigation strategy. Promoting seaweed restoration as a method for carbon dioxide removal may also offer false hope, delaying the phaseout of fossil fuels, the authors warn. The authors add, "Conserving and restoring seaweed forests is worthwhile, but we need to be realistic about what it can achieve in terms of meaningful climate change mitigation through carbon dioxide removal.
Currently, climate-driven losses of seaweed forests are orders of magnitude greater than gains due to restoration. We contend that restoring seaweed forests cannot deliver meaningful climate change mitigation at the scales and speeds required to offset our growing emissions." Seaweed carbon removal cannot keep up with climate-driven loss, PLOS Biology (2026). DOI: 10.1371/journal.pbio.3003949 Swati Mestri holds a bachelor's degree in Electronics Engineering and has worked as a content editor since 2019.
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