Thawing Permafrost Releases Dangerous Mercury
The Arctic is warming faster than any other region on Earth, with serious consequences for the environment and human health. Norwegian scientists warn that the rapid rise in temperatures, around four times the global average, could release large amounts of mercury trapped in permafrost. This includes methylmercury, one of the most toxic forms of this heavy metal.
Methylmercury is considered a powerful neurotoxin for animals and humans and is even more dangerous than elemental mercury. High concentrations can impair brain function, particularly in children. How serious the threat is became clear in 2023 in an Indigenous community in northern Canada, where a direct link was established between mental health problems, high suicide rates, and the regular consumption of mercury-contaminated fish.
Since the early 2000s, international rules, bans, and regulations have helped significantly reduce human-caused mercury pollution. However, these measures are powerless against a new, climate-related source. There are currently no effective counterstrategies for the mercury released by thawing permafrost.
Natural sources of mercury are primarily mercury-containing rocks. Through processes such as volcanism or rock weathering, the metal enters the environment, is transported over long distances, and accumulates in ecosystems. When it binds to organic carbon, methylmercury is formed, which accumulates particularly easily in food chains. Permafrost acts like a gigantic freezer: it preserves plant and animal remains, including already contaminated material, as well as mercury and its compounds for thousands of years.
For a long time, researchers assumed that about 40 kilograms of mercury per square kilometer would be released as permafrost thaws. However, a study published last year by the University of Southern California arrives at an alarming conclusion: the figure could actually be around 86 kilograms per square kilometer, more than twice as much as previously assumed.
“Permafrost soils contain more mercury than all other soils on the planet combined, plus all the oceans and even the atmosphere,” warns Josh West, Professor of Earth Sciences and Environmental Studies at the University of Southern California. His statement underscores the risk posed by the gradual loss of permafrost.
The thawing of Arctic soils is therefore not only a symbol of climate change but also a concrete threat to people and nature. Without global efforts to limit global warming, the mercury trapped in ice could become a long-term environmental and public health problem of worldwide significance.
Heiner Kubny, PolarJournal