Ocean currents carry centuries-old mercury pollution to Arctic, poisoning wildlife
By isabelle // 2025-06-18
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  • Decades of reduced mercury emissions have not lowered contamination in Arctic wildlife, with levels now 20 to 30 times higher than pre-industrial times.
  • New research reveals ocean currents transport centuries-old mercury pollution to the Arctic, where it persists for over 300 years.
  • Mercury from industrial sources takes up to 150 years to reach Greenland, poisoning top predators like polar bears and Indigenous food sources.
  • Despite global efforts like the Minamata Convention, legacy mercury in oceans continues to circulate, delaying any decline in Arctic contamination.
  • Mercury severely harms Arctic wildlife and Indigenous communities, damaging immune systems, reproduction, and neurological functions.
  For decades, global regulators have touted reductions in mercury emissions, yet Arctic wildlife continues to suffer from skyrocketing contamination levels. Now, new research reveals a shocking truth: ocean currents are transporting centuries-old mercury pollution into the Arctic, where it persists for over 300 years, poisoning top predators like polar bears and seals—and the Indigenous communities that rely on them for survival. Despite global efforts to curb mercury emissions since the 1970s, concentrations in Arctic animals have not declined. Instead, they’ve surged to 20-30 times pre-industrial levels, according to a groundbreaking study published in Nature Communications by researchers from Aarhus University and the University of Copenhagen. The findings expose a hidden crisis: mercury dumped into oceans decades or even centuries ago is still circulating, carried by slow-moving currents that take up to 150 years to deliver their toxic payload to the Arctic.

The mercury deception: Why emissions cuts aren’t enough

Governments and environmental agencies once claimed that reducing mercury emissions would solve the Arctic contamination crisis, but the data tells a different story. “We’ve monitored mercury in Arctic animals for over 40 years. Despite declining global emissions since the 1970s, we see no corresponding decrease in Arctic concentrations—on the contrary,” said Professor Rune Dietz from Aarhus University, one of the study’s lead authors. The reason? Mercury doesn’t simply vanish once it’s released. While airborne mercury lingers for about a year, once it enters the ocean, it can persist for centuries. This means that even if all emissions stopped today, Arctic wildlife would continue to suffer from mercury poisoning for generations.

Tracing mercury’s path

To uncover the truth, scientists analyzed more than 700 environmental samples from Greenland, including tissues from polar bears, seals, fish, and peat collected over the past 40 years. By examining six different mercury isotopes, each acting like a unique fingerprint, they identified distinct regional patterns that align with ocean current pathways. “These isotope signatures act like fingerprints, revealing the sources and transport pathways of mercury,” explained Senior Researcher Jens Søndergaard from Aarhus University. The study found that central West Greenland is influenced by Atlantic inflow via the Irminger Current, while other regions are dominated by Arctic Ocean currents. This means mercury from industrial sources in China, Europe, and North America can take up to 150 years to reach Greenland, where it accumulates in the food chain.

A silent threat to Arctic life and human health

Mercury is a potent neurotoxin, and its effects on Arctic wildlife are devastating. “Mercury affects the immune system, reproduction, and possibly sensory functions in animals, which can impact their survival,” said Professor Christian Sonne from Aarhus University. Top predators like polar bears and toothed whales now carry mercury levels far exceeding safe thresholds, putting entire ecosystems at risk. But the threat doesn’t stop there; Indigenous communities that rely on these animals for food are also at risk of mercury poisoning. The findings cast doubt on the effectiveness of the United Nations’ Minamata Convention on Mercury, which aims to reduce global mercury pollution. While atmospheric emissions have declined, the study shows that ocean currents are still delivering legacy mercury into the Arctic, where it persists for centuries. “Transport of mercury from major sources like China to Greenland via ocean currents can take up to 150 years,” said Dietz. “This helps explain the lack of decline in Arctic mercury levels.” The Arctic has become a dumping ground for mercury pollution that should have been cleaned up decades ago. Instead of disappearing, it’s been silently circulating in ocean currents, waiting to resurface in the bodies of polar bears, seals, and the people who depend on them. Sources for this article include: ScienceDaily.com Nature.com Earth.com
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