Scientists warn climate change could increase toxic mercury exposure through seafood

Climate change could alter the global movement of mercury and increase health risks for humans, particularly through contaminated food, according to researchers whose findings were published in the journal Science.

The study focuses on methylmercury, a highly toxic form of mercury that accumulates in living organisms and becomes more concentrated as it moves up the food chain, eventually reaching humans through the foods they eat.

Researchers explained that human activities over thousands of years have increased mercury concentrations in the atmosphere, soils and oceans. Although policies have been introduced to reduce emissions, mercury already accumulated in the environment can continue circulating between water, land and air for years.

Global warming could release some of this stored mercury back into the environment. Wildfires, for example, can release mercury from soil and vegetation into the atmosphere. In aquatic ecosystems, rising water temperatures and the expansion of low-oxygen zones could favor microbial processes that convert mercury into methylmercury.

However, the overall risks depend on several interacting environmental processes. The researchers called for more long-term measurements and models that account for mercury exchanges between the atmosphere, land and water. They also highlighted the need for closer monitoring in sensitive regions, including the Arctic and the tropics.