The dust from the “Red Dawn” that enveloped Sydney in 2009 went on to fertilise the ocean in a natural form of geoengineering. Because Australian dirt is particularly high in iron, it encouraged the mass growth of phytoplankton – microscopic plants that turn the sea green and, when grown in large numbers, cleanse the atmosphere by removing carbon dioxide.

Image: satellite data showing mass growth of phytoplankton (red) in the Tasman Sea. Source: Marine and Freshwater Research