Seaweed Crafts Clouds

By Stefanie Jones

Cloudy skies in coastal areas may be caused by stressed seaweed, claim scientists at the University of Manchester. The anxious algae spew chemicals which cause clouds to form while trying to protect themselves against oxidizing gases.

The team found that kelp releases large quantities of iodine-containing compounds into the coastal atmosphere when they are under stress. These compounds detoxify ozone and other oxidants that would otherwise damage the seaweed, and in doing so they produce a form of molecular iodine around which clouds may form.

“How do you stress seaweed?” I hear you ask. According to lead author Dr Frithjof Kupper, exposure to intense light, desiccation or atmospheric ozone during low tides can all serve to upset the kelp. It is now known whether other factors such as bully-boy barnacles and insensitive whelks are also stressful for the coastline community.

“The increase in cloud condensation nuclei by kelps could lead to more extensive, longer-lasting cloud cover in the coastal region – a much moodier, typically British coastal skyline” adds co-author Dr Gordon McFiggans, “The findings are applicable to any coastal areas where there are extensive kelp beds. In the UK, these are typically places like the Hebrides, Robin Hood's Bay and Anglesey.”

Reporting their findings in the Proceedings of the National Academy of Science, the research team also showed that this stress reaction plays an important role in the global biogeochemical cycle of iodine, and in removing ozone – a toxic gas – close to the Earth’s surface. We’d better start upsetting that seaweed.

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