Joan O. Grimalt

Although human-caused mercury emissions have been declining since 1990 in Europe and North America and since 2010 in East Asia, large reserves have accumulated in the soil and water. A Perspective article published in Science and written by two researchers from the Blas Cabrera Institute of Physical Chemistry at the CSIC warns that climate change—through global warming, wildfires, permafrost thaw, changes in precipitation, and altered ocean conditions—may be increasing the mobilization of accumulated mercury. According to the authors, this phenomenon may exacerbate risks to the environment and the health of humans and other organisms, primarily due to its concentration in shellfish and fish. 

A model has analysed mercury concentrations in rivers around the world from 1850 to the present day. The results, published in Science Advances, conclude that levels have doubled and even tripled since the Industrial Revolution: before 1850, rivers carried approximately 390 metric tonnes of mercury to the oceans each year, and today that figure has risen to around 1,000 metric tonnes. According to the authors, these results have implications for human health and wildlife, as mercury compounds are neurotoxic, can accumulate in fish and pose a health risk through consumption.

Mercury concentrations in tuna have remained stable between 1971 and 2022, even though emissions of this metal from human activities have decreased over the same period, a study says. 'Aggressive' emission reduction targets are needed to achieve measurable declines in concentrations of this pollutant, which is toxic for human health, the authors write in the journal Environmental Science & Technology Letters. The Minimata Convention on Mercury, a global treaty that entered into force in 2017, bans new mercury mines and includes provision to reduce mercury use, but mercury has already accumulated in the ocean 'for centuries', the article says.