Why it’s ambiguous rather than right or wrong

• The prediction was explicitly conditional: if governments treated seaweed/kelp‑based ocean carbon sequestration as a crisis and invested roughly $1 billion in a focused program, an effective engineered biological solution could be developed and deployed within about five years.
• In reality, that antecedent never occurred. U.S. and other governments have only committed tens of millions of dollars to marine carbon‑dioxide‑removal (mCDR) research in total, spread across many approaches (seaweed cultivation, ocean alkalinity enhancement, electrochemical methods, etc.), not a dedicated ~$1B crash program for kelp/seaweed sequestration alone. For example:
  • A 2023–2024 World Resources Institute review notes NOAA’s National Oceanographic Partnership Program funded about $24 million for mCDR research in 2023, and DOE budgeted $10 million in 2024 for biological ocean CDR R&D, plus a $20M CDR purchase pilot; these funds cover multiple ocean‑CDR methods, not just seaweed. (wri.org)
  • The same WRI piece highlights that the National Academies recommended more than $1 billion over 10 years for all ocean CDR research, but this is a recommendation, and proposed U.S. bills to authorize such levels of funding (including for ocean CDR broadly) had not been passed as of 2024. (wri.org)
  • Individual seaweed projects are much smaller: Norway’s JIP Seaweed Carbon Solutions pilot, for example, has a budget of about NOK 50 million (roughly a few million USD), and is framed as a three‑year pilot to test feasibility, not a crisis‑scale deployment program. (dnv.com)

Because the required funding and program scale never materialized, we have no empirical test of Friedberg’s five‑year timeline. That makes the prediction neither clearly correct nor clearly falsified.

State of seaweed/kelp‑based CDR by 2025

• Independent assessments describe seaweed‑based carbon removal (e.g., large‑scale cultivation plus sinking of biomass) as early‑stage and largely untested, with substantial uncertainties about effectiveness, durability of storage, and ecological risk. WRI characterizes ocean CDR approaches, including seaweed cultivation, as approaches that still need significant research, field trials, and governance frameworks before any large‑scale deployment. (wri.org)
• Project Drawdown’s 2025 assessment of “Deploy Ocean Biomass Sinking” (which includes seaweed sinking) concludes it is “Not Recommended” as a climate solution right now: it is not ready, evidence is limited, effectiveness is unclear, and cultivating seaweed at climate‑relevant scales is probably not feasible. (drawdown.org)
• Private ventures focused on kelp‑based carbon removal, such as Running Tide, attracted on the order of tens of millions in investment but remained at pilot scale and faced scientific, regulatory, and business challenges; Running Tide itself shut down operations in 2024. (publicnewsservice.org)

These facts show that, in the actual low‑funding world, no “effective, engineered biological solution” based on seaweed/kelp CDR has been developed and deployed at global, climate‑relevant scale by 2025. However, Friedberg’s claim was about what would be possible under a very different funding and prioritization scenario that never occurred. Since that scenario was not realized and we are not five years past any such billion‑dollar crash program, we cannot fairly judge the five‑year timeline itself as right or wrong.

Because the key condition of the prediction (a ~$1B crisis‑scale government program specifically for seaweed/kelp‑based ocean CDR) was never met, and thus the timeline was never actually tested, the correct classification is “ambiguous.”