Climate scientists have already warned that carbon released by thawing permafrost will only accelerate the pace of climate change. A newly-published paper has added weight to those warnings, while another introduces a new concern: the release of large quantities of toxic mercury.
In a paper published in the academic journal Environmental Research Letters, Joshua Dean, postdoctoral researcher at Vrije Universiteit Amsterdam, and several colleagues examine the quantity of “old carbon” – carbon pre-dating the industrial age – in the headwaters of the western Canadian Arctic. This may be evidence of the destabilization of old carbon and the phenomenon scientists call ‘permafrost carbon feedback,’ whereby a warming climate releases stored carbon from permafrost, which in turn accelerates the pace of climate warming.
There’s a great deal of carbon stored in permafrost, perhaps the equivalent of half the carbon emitted by fossil fuels since the dawn of the Industrial Revolution. Previous studies had been hampered by their inability to distinguish ‘old’ from ‘new’ carbon.
This paper finds that 30% to 40% of carbon in headwaters predates the industrial era. The evidence does not yet show that permafrost carbon feedback is underway. However, the findings in this paper can serve as a baseline. Subsequent studies will be needed to assess whether permafrost carbon feedback is becoming an issue.
More conclusive are the findings in a paper published in Geophysical Research Letters, authored by Paul F. Schuster of the U.S. Geological Survey and several colleagues. According to that paper, permafrost soils in the Northern Hemisphere hold nearly twice as much mercury as all other soils, the ocean and the atmosphere combined.
The paper estimates that between 695,000 tonnes and 2.6 million tonnes of natural mercury are found in Northern Hemisphere permafrost. Roughly half of that tonnage is frozen in permafrost. Climate science estimates a reduction in the area of Northern Hemisphere permafrost by 2100 of anywhere from 30% to 99%, raising the possibility of a large release of mercury into the atmosphere, “with unknown consequences to the environment.”