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"Mercury Bomb," an unknown weapon until recently, yet a deadly one, is a gift to humanity from climate change. So, what is it after all? To answer this question, we have to know a little bit about this metallic element in liquid form, its properties and how it can affect, or more precisely, kill human beings, including animals, and threaten the food chain. Known as "liquid silver" because of its shiny silvery appearance, mercury is a naturally occurring substance.
It is also an inevitable by-product of coal-fired power plants and aqueous waste of the chemical industries. The element is highly toxic, acting as a potent neurotoxin by binding to and inhibiting the function of enzymes and proteins critical for nerve cell function. When released into the atmosphere, mercury settles in nearby streams and rivers, thereby causing considerable damage to the aquatic ecosystem by polluting the rivers of the region.
It eventually enters the food chain via algae and infects all forms of wildlife, in the rivers and on land, from fish to birds to mammals, whose diet includes fish. The metallic element circulates in small amounts through the natural world too, because it is absorbed by plants, which then die and become part of the soil. Besides, because of an effect called the Cold Trap, our planet's natural atmospheric circulation tends to funnel pollutants toward high latitudes, leading to mercury accumulation in the Arctic region, where it bonds naturally to organic matter in the permafrost, and remains trapped for thousands of years.
It should be noted that the Arctic communities have no typical mercury-producing industries. What is permafrost? As the name suggests, it is a layer of soil and rock, with some extending 1,500 metres into the ground, that remains frozen. There are about 23 million square kilometres of permafrost covering roughly 25 percent of exposed land surface not covered with glaciers.
It is found mainly in polar regions and high-latitude areas, such as the Arctic, Siberia, Alaska and northern Canada. In summer, the top several metres melt, creating an active layer where plants can take root and refreezes in winter, while the deeper layers remain permanently frozen. This unending icy mass and its impressive size is a vital feature of the Earth's coldest climates with important impacts on human and natural systems.
It acts as a gigantic storage vault for mercury, various minerals, dangerous microbes, viruses and pathogens, alongside greenhouse gases (GHG), mainly carbon dioxide and methane that are responsible for rising global temperatures. The amount of mercury stored in the permafrost eclipses the amount in the oceans, soils, atmosphere and biosphere combined. Hence, keeping mercury, together with the GHGs, locked away in the permafrost is enough reason to make sure these landmasses do not melt.
That is why climate scientists consider the health of our permafrost a likely climactic tipping point. However, as the Arctic continues to warm as a result of climate change—four times faster than the global average—due to the phenomenon of "Arctic amplification," which is enhancement of near-surface air temperature over the Arctic relative to lower latitudes, permafrost is thawing at unprecedented rates in many areas, reaching deeper into the ground. Permafrost is therefore not so permanent and is rapidly becoming unstable as the planet becomes warmer.
During a recent trip to Alaska with my family, we saw first-hand the physical effects of permafrost thawing—ground subsidence that buckled highways, damaged railroads, airstrips, homes and other structures, as well as uprooted trees. As it defrosts, permafrost also releases whatever materials were locked inside of it, ranging from GHGs to toxic metals like mercury. Specifically, mercury that has been locked in the permafrost for millennia is being eroded by rivers and released into the environment.
When released, it is often converted by microbes into methyl mercury, which is a neurotoxin that accumulates in the bodies of humans through the foods we eat. A new study published in the Environmental Journal Letters (August 2024) concludes that the released mercury will potentially set off a "mercury bomb" that could greatly impact some millions of people living around the Arctic Circle. According to the researchers, a "giant mercury bomb" in Alaska is being washed away by rivers such as the Yukon River, depositing copious amounts of mercury into the riverbanks.
What effects will the mercury bomb have on humans? The researchers note that "Decades of exposure, especially with increasing levels as more mercury is released, could take a huge toll on the environment and the health of those living in these areas." In fact, they believe that leaked mercury may endanger approximately three million people who live in areas where permafrost is predicted to vanish completely by the year 2050. Of the many substances that interact negatively with our physiological systems, mercury is the most dangerous because when ingested, it is stored in our body and has cumulative effect.
The silvery metal can have serious effects on our nervous system, spanning from tremors, memory problems, cognitive thinking, brain and kidney damage, coordination issues (trouble walking) and mood changes to developmental issues in children, notably their motor skills. Pregnant women and children are primarily at risk of mercury poisoning. Eating fish from mercury polluted rivers can cause severe disability including deafness and blurring of vision, mental derangement, neurological defects and even death.
Mercury poisoning among indigenous people is of great concern. In Canada, traditionally fish-eating Aboriginal Peoples classed as Indians have been reeling from the harmful effects of mercury poisoning in their fish, where the pollution has been linked to high rates of attempted suicide among youth. One of the deadliest episodes of mercury poisoning occurred in 1953 among people who ate seafood from Minamata Bay (Japan) into which large quantities of methyl mercury was released by a chemical factory.
A particularly disturbing study shows that one-fifth of all Americans may have mercury levels exceeding EPA recommendations of no more than one part per million. No other pollutant even comes close to mercury for violating federal standards. Finally, for millennia, the Arctic has kept our planet healthy and happy by locking away GHGs, mercury and other toxic metals.
But after two centuries of an unyielding fossil fuel addiction, the ticking mercury bomb is waiting to explode with far-reaching consequences. Dr Quamrul Haider is professor emeritus at Fordham University in New York, US. Views expressed in this article are the author's own.
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