Scientists have warned about yet another side effect of global warming – trapped in the permafrost of Northern Hemisphere lies more than twice the amount of mercury in the rest of the earth. A warming climate could release large amounts of this dangerous toxin that has serious health effects in humans and animals, ranging from neurological problems, damage to various organs to birth defects.
Scientists warn that rising air temperatures due to climate change could defrost the existing permafrost layer and this could release a large quantity of mercury that could potentially affect ecosystems around the globe, phys.org reported.
The findings, published in Geophysical Research Letters, found 793,000 tonnes of mercury in frozen permafrost soils and another 863,000 tonnes in unfrozen soils in the northern permafrost region. Combined, this is equivalent to 122,000 litres of liquid mercury – an amount that is about 10 times the total industrial mercury emissions in the last 30 years or so and makes it the largest reservoir of mercury on the planet. Currently, humans emit about 2,000 tonnes of mercury every year through industrial activity, said Down To Earth.
‘Permafrost’ is defined as any soil that has been frozen for more than two years. In the Northern Hemisphere, permafrost accounts for about 22.79mn sq km of land – or roughly 24% of exposed Earth, according to the National Snow and Ice Data Center, said LiveScience. Over time, naturally occurring compounds in the atmosphere, such as mercury and carbon dioxide, can bind with organic material in the soil and be frozen into permafrost, potentially remaining trapped underground for thousands of years before it thaws, said the new study.
Researchers also point to the fact that this large amount of mercury might pose a danger to the environment. Mercury has negative reproductive and neurological effects on animals and is known to accumulate in both water and terrestrial food chains.
“There would be no environmental problem if everything remained frozen, but we know the Earth is getting warmer,” study author Paul Schuster, a hydrologist at the US Geological Survey in Boulder, Colorado, said in a statement.
“This discovery is a game-changer.” Researchers have already observed climate-change-induced permafrost thawing, and there is likely more on the way: According to a 2013 study, the Northern Hemisphere will lose anywhere from 30 to 99% of its permafrost by 2100, assuming current human greenhouse-gas emissions continue unabated. Previous studies have attempted to account for the billions of tons of carbon dioxide, methane and even “zombie pathogens” that could be loosed into the air and the oceans by melting permafrost. The environmental impact of a large-scale mercury leak, however, remains an unpredictable problem.
One major concern is that this trapped mercury could seep into nearby waterways and transform into methylmercury, a toxin that can cause motor impairment and birth defects in animals, Edda Mutter, science director for the Yukon River Inter-Tribal Watershed Council, said in a statement, according to media reports. Such contamination could travel swiftly up the food chain from micro-organisms to humans, said Mutter, who was not involved in the new study. The researchers are currently working on a follow-up study modelling the release of permafrost due to climate change, according to the statement.
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