Researchers have discovered seaweed could play a crucial role in enhancing global food security after global catastrophe such as nuclear war.

The team, including Te Whare Wānanga o Waitaha | University of Canterbury (UC) Mechanical Engineering Associate Professor David Denkenberger, found the growth of seaweed, and therefore its potential to become an important food source, increases after an abrupt and prolonged disturbance to sunlight seen after more severe nuclear conflicts or a large volcanic eruption.

"Investing in the construction of seaweed farms could prevent global famine in abrupt sunlight reduction scenarios, potentially averting a significant number of deaths from starvation," says Associate Professor David Denkenberger.

Researchers from UC, Alliance to Feed the Earth in Disasters (ALLFED), Louisiana State University, and University of the Philippines Diliman, used the results of a climate model where particles were injected into the atmosphere to replicate the impacts of a significant global event, such as a volcanic eruption or nuclear war.

Such events would be catastrophic for conventional agriculture where there would be limited sunlight and cropland temperature more than 10°C lower for many years – otherwise known as a nuclear winter. The research addresses the critical need for resilient food sources that can be grown after global catastrophes.

Associate Professor Denkenberger said the study revealed that seaweed production could be quickly scaled up to meet a substantial portion of global food application demand, reaching an equivalent of 45 percent within nine to 14 months. “Most of this can be used for animal feed and biofuel, as human consumption is limited to 10 to 15 percent due to the high iodine content in seaweed, which could cause adverse health effects without processing.”

"Seaweed has a high potential to be an important pillar of global food security, even after a nuclear war. This study opens avenues for further research and calls for investments into scaling up seaweed farming capacity to ensure food security in times of crisis,” says lead author Dr Florian Ulrich Jehn from ALLFED.

The preprint of the study was selected as one of the most exciting and interesting entries out of 17,000 submissions to the European Geosciences Union (EGU) conference this year in Vienna.

Professor Cheryl Harrison, an ocean modeller from Louisiana State University, says their previous studies have highlighted the need for alternative and reliable food sources.

"Given that our previous studies showed that agriculture and fisheries production would plummet, alternative food sources like seaweed will be critical for global and regional food security after sunlight reduction scenarios, such as nuclear war and large volcanic eruptions.”

“It’s only a matter of time before the latter happens, so we need to be ready. Because the ocean does not cool down as rapidly as land, marine aquaculture is a very good option.”

Increasing seaweed growth also has other benefits, particularly for the environment. It grows without taking up land, water or chemicals required for on-land crops. Seaweed fed to cattle could also significantly decrease the emissions of methane and it can store carbon from the air, helping to slow the warming of the planet.