Mountains are warming twice as fast as the rest of the world

Bob Berwyn writes: Mountain temperatures are increasing more quickly than the global average, at a rate closer to that of the Arctic, and climate researchers are trying to figure out why. They suspect that the accelerated mountain warming is due to an effect documented in the Arctic—loss of albedo. The peaks are losing their shiny white blanket of snow and ice that reflects the sun’s radiation back to space. Instead, darker-colored ground absorbs heat, amplifying the heat-trapping effect of greenhouse gas pollution.

But there’s not quite enough data yet to prove the conventional wisdom of rapid mountain warming, says University of Portsmouth geographer Nick Pepin, who led a 2015 study that tried to assess climate change impacts to mountains on a global scale. Are they really warming as fast as we think?

“I think the overall feeling on this is, probably they are, but we don’t know for sure,” he says. Temperature readings taken between 1,000 and 3,000 meters confirm the trend, but data is sparse from higher elevations. There are very few ground-based weather stations above 3,000 meters and none above 5,000 meters, Pepin says, advocating for an expansion of mountain climate
Satellite data can be used to measure land-surface temperature, and it shows that higher elevations are warming more than areas lower down, but the satellites aren’t as accurate as ground-based readings. Direct observations are needed to validate the satellite data, Pepin says.

Without better information, people risk substantially underestimating the severity of many already-looming problems, including a proliferation of damaging landslides, water shortages in densely populated lowlands—especially in Asia—and the extinction of some mountain plants and animals.

Pepin’s recent study zoomed in on the Tibetan Plateau, which holds so much snow and ice that it’s sometimes called the Third Pole. Temperatures in the region have climbed steadily. Above 4,000 meters in elevation, the rate of warming has increased by an astounding 75 percent in just the past 20 years, compared to areas below 2,000 meters.

“If we’re right, the social and economic consequences could be serious, and we could see much more dramatic changes much sooner than previously thought,” Pepin says.

The Tibetan Plateau is the source of 10 of Asia’s biggest rivers, including the Ganges, Indus, and Mekong basins. These rivers provide water to more than 1.35 billion people, 20 percent of the world’s population. The melting glaciers foreshadow a major water supply crisis, and there’s also a more immediate danger; destabilized ice masses threaten mountain communities with avalanches, landslides, and floods. [Continue reading…]

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