Volcanic ash: A possible ally in the fight against climate change

Technological solutions to mitigate climate change often discuss renewable energy or carbon capture and storage. But what about volcanic ash?

Writer: Chelsea Tripp
Editor: Andrey Chau
Artist: Patrick Marenda

Soaring temperatures, fluctuations in rainfall, and rising gas emissions. These are some of the issues exacerbated by climate change, and do not cast a positive outlook for dealing with what the Lancet has described as the “biggest health threat facing the world”. When thinking about climate change solutions, we envision a more eco-aware world. A population that cycles more, abandons red meat for trendy vegan alternatives, and proudly displays shiny solar panels on the roofs of their homes. These lifestyle changes emphasise the consumer’s responsibility to help slow down climate change, but until enough individuals can make these changes, alternative techniques are worth investigating. One innovative technology being considered is the distribution of volcanic ash into the oceans, storing carbon dioxide. So, how does volcanic ash present a unique solution to the challenge of climate change, rather than displacing the burden upon the individual? 

Volcanoes are commonly found close to or underneath the water. According to the US Geological Survey, 75% of approximately 1,500 active volcanoes worldwide are based near the Pacific Ocean, an area nicknamed the ‘Ring of Fire’. However, volcanoes are paradoxical, as they can either help or hinder climate change. During an eruption, they produce sulfur dioxide particles. When merged with water, these particles reflect energy from the sun, thereby promoting cooling. They also generate carbon dioxide, a greenhouse gas notoriously known for its contribution to the planet’s global heating. 

A more unusual method to remove atmospheric carbon dioxide is through the artificial placement of volcanic ash in our oceans. Following a volcanic eruption, ash, or tephra, is naturally produced and deposited on the ocean floor. Whether naturally produced or synthetically placed, the knock-on effect of these ash deposits serve to lock away carbon for hundreds and potentially thousands of years. As such, tephra is a crucial climate change solution, acting as the ocean’s very own carbon storage units. As carbon sinks, the ocean also entraps more carbon from the air than will be released, absorbing around one third of carbon dioxide emissions worldwide. However, the effectiveness and safety of using volcanic ash in the fight against climate change is still uncertain. 

Researchers suggest that for every 50,000 tonnes of extra volcanic ash placed into the ocean, nearly 2,750 tonnes of carbon dioxide could be stored by the seabed, at only £40 per tonne of carbon dioxide removed. Compared to other greenhouse gas removal techniques, such as carbon capture and storage, which transforms carbon dioxide into its liquid form before storing it underground, volcanic ash is relatively cost-effective as it does not require the same expensive technology. Earlier evidence from the 2008 volcanic eruption in the Aleutian Islands, Alaska, suggests that marine algae benefit from the iron present within volcanic ash, as this nutrient aids their growth. Although this method builds upon a naturally occurring process, there are concerns that an excess of volcanic ash for prolonged periods could disrupt the delicate balance of our oceans, and impact how well they store carbon. It is also possible that a heavy flow of ash spanning a large area could negatively impact the ocean’s pH or affect certain coral species due to the excess iron and magnesium.

Artificially placed volcanic ash within our oceans has the potential to store large amounts of carbon dioxide, at much lower costs without the need for complex technology, and with further research, could have additional benefits for marine life. But for this technique to be successful, we cannot solely rely on technological innovation to rescue us from an anthropogenic problem. The UK plans to cut carbon dioxide emissions by 68% in 2030, and a united effort from science, technology, leaders, ordinary individuals, among other societal sectors, is fundamental to reaching these targets. 

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