Himalayas

Spring is go time for climbers who hope to summit Mount Everest, Earth’s highest peak above sea level. Hundreds of mountaineers from around the world travel to Asia in April and May, headed for base camps in Nepal and Tibet. But jagged peaks won’t be the only thing they see. Especially on Everest’s more heavily traversed Nepal side, they’ll find fields of garbage – including cans, bottles, plastic and human and animal excrement. Each year, more than 60,000 trekkers and climbers visit the Sagarmatha National Park and Buffer Zone, a high-altitude swath of the Khumbu region in northeast Nepal that includes Everest and seven other peaks. Some 400 to 500 climbers attempt to summit Everest every year. The trash problem first became evident in the 1980s and 1990s, when climbing on the mountain and trekking in Khumbu began to increase. Climber and trekker numbers have further skyrocketed in the past 20 years. Most coverage of this issue focuses on nega...

The Himalayas stand as Earth’s highest mountain range, possibly the highest ever. How did it form? Why is it so tall? You might think understanding big mountain ranges requires big measurements – perhaps satellite imaging over tens or hundreds of thousands of square miles. Although scientists certainly use satellite data, many of us, including me, study the biggest of mountain ranges by relying on the smallest of measurements in tiny minerals that grew as the mountain range formed. These minerals are found in metamorphic rocks – rocks transformed by heat, pressure or both. One of the great joys in studying metamorphic rocks lies in microanalysis of their minerals. With measurements on scales smaller than the thickness of a human hair, we can unlock the age and chemical compositions hidden inside tiny crystals to understand processes occurring on a colossal scale. Measuring radioactive elements Minerals containing radioactive elements are of special interest...

In August 2023, residents of Juneau, Alaska, watched as the Mendenhall River swelled to historic levels in a matter of hours. The rushing water undercut the riverbank and swallowed whole stands of trees and multiple buildings. The source for the flood was not heavy rainfall – it was a small glacial lake located in a side valley next to the Mendenhall Glacier. Glacier-dammed lakes like this are abundant in Alaska. They form when a side valley loses its ice faster than the main valley, leaving an ice-free basin that can fill with water. These lakes may remain stable for years, but often they reach a tipping point, when high water pressure opens a channel underneath the glacier. The rapid and catastrophic drainage of lake water that follows is called a glacial lake outburst flood, or GLOF for short. The flood waters race downstream over hours or days and often hit unexpectedly. Suicide Basin, a glacier-dammed lake, has flooded the Mendenhall River...