Our Phosphorescent World

Summary

On the Hebridean island where I live, off the western coast of Scotland, windy days are smelly ones because large amounts of seaweed wash ashore, accumulating on the northern ends of beaches. For some, this might be an unremarkable occurrence, but here, on our small island, we see seaweed as a gift. There are around 1,000 of us – crofters and office workers, incomers like me, and those who have stayed forever. Daily travel is dependent on the tides, the swells, and the weather at the ports that host the ferries. Limitations like these keep Earth’s cycles in continual focus. I like it this way. I lock my windows when a storm is coming, and I watch the waves. Afterward, I go and look for seaweed. In the winter, when storms are stronger, a man from the village next to mine drives his tractor down to the beach and drags the seaweed up to a higher spot. He creates a towering pile that smells like faeces. It feeds the island. Here, we use seaweed as a fertiliser, because it is rich in elements that humans and plants both need for living, such as nitrogen and potassium. It also contains one particular substance that I have spent much of my life thinking about: phosphorus. Seaweed on the shores of Benbecula, an island in the Outer Hebrides in Western Scotland. Courtesy Davide Gorla/Flickr Stored in rock and organic material, phosphorus cycles slowly around Earth, through magma and mountains, down rivers, through waste and into oceans. Without it, there’d be no life – every living being needs it to grow. Unlike other mined materials, we all eat it. In the human body, it gives our cells energy, structure and identity, and it is particularly concentrated in our bones. Rare enough to be notable, common enough to be necessary, phosphorus tracks the development of our planet. Over billions of years, as life and Earth evolved, phosphorus held the two together. Two hundred million years ago, when Pangaea broke apart, all those newly exposed continental edges leaked phosphorus into ...