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PERMAFROST?: Some scientists question whether the $4-billion rail line will survive as is or require major reconstruction.
© ABRAHM LUSTGARTEN

Building a railway across the unstable soil of the Tibetan Plateau was an improbable endeavor from the start, but an army of Chinese government engineers did it anyway.

Now, with the frozen soil disturbed by the process of laying down the rail and a warming climate on the plateau, some scientists question whether the $4-billion rail line will survive as is or require major reconstruction.

Three years after the railway opened in 2006, international research shows that the Tibetan territories are among the fastest warming, and fastest melting, on the planet. The research into the fate of glaciers and the permafrost soils—done by the United Nations, China's scientific agencies, and several independent scientists—is not focused on the railway. But the work raises concerns that the warming ground could lead to a buckling of the railway.

(Im)permafrost
According to a 2007 global outlook from the U.N. Environment Programme (UNEP), the frozen soil of the Tibetan plateau has warmed about 0.3 degree Celsius over the past 30 years—after the poles, faster than anywhere else on the planet. Where human activity has disturbed the soil, such as during the construction of the railway, the rate is double, 0.6 degree C.

That might not seem like much, but it is enough to outpace the rate predicted by railway construction engineers for the landmark rail line, which has carried some six million passengers and five million tons of cargo since opening day. And the news would seem to get worse: UNEP says the permafrost area surrounding the nearby Qinghai–Tibet Highway decreased some 36 percent in size in the 20 years leading up to 1995, the period for which data were recorded. By the end of this century, the report says, China's permafrost (which is almost entirely on the Tibetan plateau) could decrease by half again. By 2050, another U.N. report predicts, the glaciers on the plateau will have shrunk by one third.