An ever taller Everest?

A team of American climbers last month launched an effort to measure whether the world's tallest mountain is growing higher and, if so, at what rate. Wally Berg of Copper Mountain, Colo., successfully planted a Global Positioning System (GPS) receiver within about 60 feet of Everest's summit. It recorded altitude data for 5 days until another climber retrieved it. Climbers will take a second measurement from the same spot, where Berg screwed in a metal plate, in a few years.

Using GPS measurements from other locations and conventional surveying methods, researchers have estimated that Everest Is rising an average of 1 to 2 inches per year, pushed up by the collision of India's continental plate with Asia's. However, erosion of the summit may ensure that record books need not be revised, says Charles Corfield of Palo Alto, Calif., science officer for the American climbing team.

The most widely accepted estimate of Everest's height, 29,028 feet, Is inexact because of the limits of traditional surveying techniques. Previous GPS readings from the summit were imprecise because the rocky peak is covered by a snowcap of unknown depth that grows and shrinks over the year.

The new data recorded near the summit are the most accurate to date because Berg activated the receiver at a rocky outcrop not covered by snow. In addition, the data were crosschecked against GPS readings at nearby, lower elevations, Corfield says.

Because they can indicate the buildup of seismic stress, the readings may help researchers predict the next earthquake in the Himalayas.

The climbing team that planted the receiver is affiliated with Bradford Washburn, a noted Himalayan cartographer and founding director of the Boston Museum of Science.