Seaweed cultivation: a cost-effective strategy for food production in a global catastrophe

An event such as a large volcanic eruption, nuclear winter, and asteroid/comet impact has the potential to seriously reduce incoming sunlight, impacting the global climate, and crop yields. This could have catastrophic impacts on human nutrition, unless the food system can adapt. One possible answer is seaweed, where growth is projected to be less impacted (or even enhanced) by the climate shock; however, this requires seaweed to be cost-effective, which has not yet been assessed. Here, we estimate the economic viability of producing Gracilaria Tikvahiae seaweed under the climatic conditions of a severe 150 Tg nuclear winter, as a benchmark. To do this, we incorporate projected yields and estimated costs under either a capital-intensive or labor-intensive model, including drying, assuming sales only occur in the initial 7 years when food prices would be highest. Overall, we find that seaweed costs would range between $ 400 and 450/dry tonne for the lowest cost clusters, and could potentially be produced in significant quantities, up to 250 million tonnes annually. Given the rise in food prices expected post-disaster a scaleup in seaweed would likely be justified, and could support global nutrition, either via direct consumption or when used as animal feed.