Of all the climate change issues that have been melodramatically dubbed a “carbon bomb” in recent years—tar sands projects in Alberta, catastrophic wildfires in Indonesia, holes in Australia’s seagrass meadows—it seems the thawing of permafrost in the Arctic is most likely to live up to the hype. There’s a staggering amount of methane and carbon dioxide, like hundreds of gigatons worth, trapped under the permanently frozen layer of soil and rock in the form of ice crystals and biomass. If released due to the ongoing crescendo of warming in the Arctic, it could trigger a global feedback loop and burn us all to a fucking crisp. Yet there’s another very real issue associated with thawing permafrost that’s received far less attention outside of industry circles, perhaps because of the lack of a catchy apocalyptic phrase to accompany it.
For decades, mine operators in Northern Canada have stored waste rock and tailings waste—the “pulverized rock slurry” byproduct of mineral processing that’s filled with skeevy chemicals like arsenic, lead, and mercury—in frozen dams reinforced with permafrost, an option far cheaper than constructing artificial structures to house the goop. But if such walls thaw, allowing air and water to interact with the highly reactive tailings, widespread “acid mine drainage” (AMD) could occur. Such a process can generate sulphuric acid and result in the leaching of heavy metals into nearby soil and water sources.