• Choose a category
• All
• Classic-Fiction

On Shaky Grounds

Permafrost is permanently frozen ground. It is ubiquitous around the Arctic and high elevations of the world, and extends surprisingly far south in the cold eastern interiors of Canada and Siberia (see maps on pages x-xiii). The topmost part thaws inches deep each summer, but beneath this so-called “active layer,” the soil stays hard and frozen year-round. As such, it offers a solid base on which to build roads, buildings, pipelines, and other infrastructure—so long as it always stays frozen. The trick is to not warm it up.

An entire subfield of civil engineering is devoted to building things on top of permafrost without somehow warming it. Houses are raised up off the ground on pilings, roads and railroad tracks are perched atop thick pads of insulating gravel, and so on. Oil pipelines require very careful design because flowing fluid generates a surprising amount of heat, and a ruptured pipeline is an environmental disaster. The world’s latest permafrost engineering feat, completed in 2006 at a cost of USD $4.2 billion, is China’s Qinghai-Tibet Railroad crossing the Tibetan Plateau from Golmud to Lhasa.

But no amount of clever engineering can stop regional permafrost from thawing from milder, snowier winters (snow insulates the ground). When that happens, unless the geological substrate is firm bedrock, the built structures are compromised. The substrate returns to the structural strength of wet mud, or peat, or whatever else it is geologically composed of. The ground slumps, roads buckle, and foundations crack.373 Pipelines and train tracks become kinked and wavy when they ought to be straight. Even slight undulations force trains to slow down greatly or risk derailment. The sluggardly speeds I’d noticed for parts of the Hudson Bay Express, the otherwise lovely two-night passenger train voyage from Winnipeg and Churchill, was because of this. Deeper kinks require closing down the tracks for repairs. That’s what triggered the line’s closure six weeks later, when I bailed on the train (and my Amundsen shipmates) and caught a flight instead.

Fortunately for OmniTRAX, only the last leg of its long railroad to Churchill lies over permafrost. But other built structures around the Northern Rim are not so lucky. From borehole thermometry and other measurements, we know that permafrost temperatures are generally rising.374 The endgame of this process is ground slumping, tilted trees, sinkholes, and other disturbances.

Already we see evidence of this from space. Using satellites, my UCLA colleague Yongwei Sheng and I mapped out a strange phenomenon now transforming vast tracts of western Siberia. This region famously holds thousands of wellheads supplying natural gas to international markets in Ukraine and Europe. Less famous are the tens of thousands of lakes that dot its surface like so many spilled marbles. By comparing recent satellite pictures of this region with those from the early 1970s, we discovered a landscape mutating as the underlying permafrost thaws, with many of these lakes disappearing into the ground.375

Theoretically, if all permafrost were to go away entirely, about half of the world’s northern lakes and wetlands might conceivably vanish.376 But permafrost thaw is a slow process, so that won’t happen anytime soon. Deep permafrost can extend hundreds of meters downward and requires centuries or millennia to defrost. But significant reductions are expected by 2050, with climate models projecting 13%-29% less permafrost area by then, and the depth of seasonal thawing increasing roughly 50%.377 These numbers are worrisome because from a practical standpoint, the settling and buckling problems commence even when permafrost first starts to thaw. Also troubling is the fact that permafrost ground is commonly stuffed with chunks and lenses of pure ice, which drain out, exacerbating the slumping. Already in Russia, damages to the Baikal-Amur Mainline (BAM) Railroad have more than tripled. The number of threatened buildings