AGU image

The Tibetan Plateau is a major gateway for the transport of water vapor into the upper atmosphere.

SAN FRANCISCO, CA., DEC. 11, 2013 — Carbon dioxide is the major culprit everyone talks about when it comes to the globe’s warming climate. But water vapor is a potent greenhouse gas too. In fact, the climate in the tropics is largely mediated by water vapor.

But now, scientists are looking far from the equator to learn how water vapor ends up in the upper atmosphere to play a big role in shaping global warming: The Tibetan Plateau in Central Asia, commonly known as the Roof of the World.

Map showing Tibetan Plateau (Wikipedia commons)

In a talk Wednesday here at the 2013 AGU meeting, Rong Fu from the Jackson School of Geosciences at the University of Texas at Austin gave a briefing about how the Tibetan Plateau is a main gateway for the transport of water vapor from the troposphere to the stratosphere, the second major layer of the atmosphere above the troposphere that extends from about 40,000 to 160,000 feet above moderate latitudes.

Why should we care about water vapor high in the stratosphere?

“It has a significant effect on global warming,” Fu said. “It could have a significant impact on surface temperature … (and) it is not negligible.”

On the Tibetan Plateau, the rate of increase in surface temperatures has doubled since 1980, Fu said. That’s led to increased convection over the Plateau over the last decade. The result is that the concentration of water vapor over the Tibetan Plateau has been increasing since 1979. “This increase appears to explain much of the moistening of the lower stratosphere in the northern hemisphere,” Fu said.

Most of the moist air enters the stratosphere over the north end of the Tibetan Plateau, and computer simulations have confirmed that increasing surface temperatures there drive strong increases of atmospheric water vapor.

NASA Image of Tibetan Plateau (Wikipedia commons)

Fu said multi-satellite measurements of water vapor in the stratosphere are needed to verify the trend that some ground observations and computer simulations indicate.

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