A Mercury Problem Lurks in the Earth’s Thawing Permafrost

Researchers have discovered large mercury deposits in layers of dense permafrost, and they warn that the element could be released into the environment as the poles warm. 

Permafrost refers to soil, rock or ground sediment that has been frozen for more than two consecutive years. In extreme polar regions, some permafrost layers are hundreds — or even thousands — of years old. Bacteria and chemical compounds that are not destroyed by permafrost become preserved in these icy formations. But, thanks to global warming, the permafrost is melting — and releasing these chemicals.

A study published this month in the journal “Geophysical Research Letters” relates how scientists examined the mercury content of Alaskan ice cores. The mercury present in these samples suggests that the coldest polar regions are preserving nearly twice as much mercury as any other place on the planet combined.

“This discovery is a game-changer,” lead author Paul Schuster, explained. “We’ve quantified a pool of mercury that had not been done previously, and the results have profound implications for better understanding the global mercury cycle.”

Digging Deeper: How Did Scientists Conduct This Study?

The presence of mercury in permafrost isn’t particularly surprising. Atmospheric elements and compounds of all kinds can bind to material that finds its way into waterways, soil and even ice at the extremes of our planet. What is shocking about this study, however, is the amount of mercury stored in the permafrost.

Scientists extracted 13 core samples from the Alaskan permafrost and analyzed their composition for mercury and carbon. Then, the researchers scaled up that figure based on existing soil data and compared these estimates to data gathered from other permafrost sites around the world.

Given these findings, the scientists estimate that there may be more than 15 million gallons of mercury below North American permafrost. To put that in perspective, the researchers note that this figure is about 10 times that of “all human-caused mercury emissions over the last 30 years”. 

In total, the frozen and unfrozen soil in the northern permafrost region is the largest reservoir of mercury known to science.

And as Schuster, a U.S. Geological Survey hydrologist, warns, this mercury store poses a major threat as the climate heats up:

There would be no environmental problem if everything remained frozen, but we know the Earth is getting warmer. Although measurement of the rate of permafrost thaw was not part of this study, the thawing permafrost provides a potential for mercury to be released—that’s just physics.

Is Mercury Seeping Into Our Soil?

Several different kinds of mercury exist. For instance, a mercury product called Thimerosal was once used as a preservative in several vaccines. While it has fallen out of favor due to vaccine health scares, the product illustrates that not all types of mercury are harmful to humans in small doses.

But if mercury emerging from the melting permafrost were to be ingested up by small organisms, it could be converted to methylmercury and pose a serious threat.

As the World Health Organization explains:

Methylmercury then bioaccumulates (bioaccumulation occurs when an organism contains higher concentrations of the substance than do the surroundings) in fish and shellfish. Methylmercury also biomagnifies. For example, large predatory fish are more likely to have high levels of mercury as a result of eating many smaller fish that have acquired mercury through ingestion of plankton.

Methylmercury poisoning produces a range of symptoms, including loss of vision, impairment of muscles, speech, hearing and walking and muscle weakness. It can be particularly harmful for infants, even causing permanent cognitive impairment and physical disability due to a loss of fine motor skills. While there are no long-term health studies that link cancer rates to mercury exposure, research has demonstrated an increased risk of tumors in animals.

Scientists suggest that individuals living and working near permafrost regions, like Alaska’s rural farming communities, could be adversely impacted. What’s more, they note that mercury is capable of traveling great distances once in the air — meaning that this is an issue of global concern.

This study adds to the growing body of research exploring the dangers of melting permafrost, from the return of long-gone diseases to environmental  contamination.

The only way to reduce these risks? To put an end to climate change as quickly and decisively as possible.

Photo Credit: NASA Goddard Space Flight Center/Flickr


Peggy B
Peggy B5 hours ago


Kyle N
Kyle Nyesterday

Id rather bring back mercury thermometers, thermostats. thermostats now are a joke, digital thermostats are unreliable.

natasha p
natasha p2 days ago


Angela K
Angela K3 days ago

hank you for posting

Dan B
Dan B3 days ago

Jetana A.,
I think it was presented because it sounds scarier. It is a relatively minor nuisance.

Chrissie R
Chrissie R3 days ago

Thank you for posting.

KimJ M
KimJ M3 days ago


KimJ M
KimJ M3 days ago


KimJ M
KimJ M3 days ago

Interesting article

Jetana A
Jetana A4 days ago

The methane being released as permafrost melts should already be enough to motivate action. But mercury sounds scarier. Hope this "discovery" helps.