Before the Met Office was set up, and long afterwards in seaside towns, sugar kelp (Saccharina latissima) was used to forecast the weather. Plucked from rock pools, it often hung on a hook by the seaside landlady’s door. If the seaweed was limp and damp because of moist air, it was sure to rain soon. If it was dry, then the day would be fine. This species has also long been gathered for food and as a cosmetics ingredient in Asia and in the UK. More recently, seaweed has been suggested as a means of carbon sequestration comparable to rainforests. Last month, Amazon gave a huge boost to efforts to test that idea by giving a €1.5m (£1.3m) grant to set up a farm-scale trial in the North Sea. The idea is to develop methods for growing and harvesting seaweed on a large scale between the thousands of turbines being built in shallow water on the continental shelf that now cannot be commercially fished. Sugar kelp grows particularly quickly in early spring and reaches 5 metres (16ft) long in about four years. The trial by North Sea Farmers also aims to install floating solar and grow shellfish in the unused area between turbines, but will mainly focus on harnessing the potential of seaweed to slow climate breakdown.