In 2017, a new global treaty was meant to bring mercury pollution under control. But three decades of data from UK harbour porpoises show mercury is still increasing, and is linked to a higher risk of dying from infectious disease.
When the Minamata convention came into force eight years ago, it was hailed as a turning point. The global treaty on mercury commits countries to reducing mercury from coal-fired power plants, industry and products, like batteries and dental fillings.
Yet mercury levels are still rising in many parts of the ocean. Human activities such as the burning of fossil fuels have already tripled mercury in shallower ocean waters (less than 1,000m in depth) since the industrial revolution. Warmer seas and shifting food webs are exacerbating the problem by increasing the rate of accumulation in the marine food chain.
