Mapping Mount Everest

This spring, I had the amazing opportunity to lead the mapping team on the 2019 National Geographic and Rolex Perpetual Planet Extreme Expedition to Mount Everest, undertaken in partnership with Tribhuvan University. Our goals were to scan and perform detailed photogrammetry of the entire Khumbu glacier from the South Col all the way down to the toe of the glacier and to scan all of Everest Base Camp—at the highest resolution ever collected at Mount Everest.

Everest, the world's highest mountain at 8,849 meters (29,032 feet), straddles the China-Nepal border amidst a rugged wilderness of snow, ice, and rock. On its southeastern shoulder rests Khumbu Glacier, one of thousands sprawled across the Himalaya. Meltwater from these glacial terrains supplies great river systems that in turn provide essential water to huge populations in India, China, Pakistan, and Bangladesh.

It's this larger picture that makes our mapping work so important. Understanding the dynamics of Himalayan glaciers will help us anticipate how climate change will affect the water supplies upon which millions of people depend.

The ground-based mapping and scanning work of the expedition focused on collecting data and imagery that would be processed into an extremely high-resolution, 3D map of Everest Base Camp, the most detailed ever produced. Our tools are laid out here in the mapping and imagery tent at Base Camp.

We also made many photographs at ground level using 42-megapixel hand-held cameras. These images provided additional detail and texture to the 3D models and maps and contributed to the composite digital model.

In the approximately one-square-kilometer area of Base Camp we collected 364 Lidar stations, over 8,500 drone photos, and over 24,000 ground-level photos. The result: combined imagery and 3D data that vastly exceeds the accuracy and detail of previous mountain surveys.

We lived at 5,300 meters for six weeks. The constant fatigue from having only half of the oxygen at sea level is like nothing I’ve previously experienced in the field. Just walking up the ten-meter hill to our tents would leave me breathing hard.

And then there were the illnesses that hit most of our team. I was one of the first to go down with an upper respiratory infection that I got on the ten-day trek up to Base Camp. It left me sleeping most of the day after I arrived. After only two days at Base Camp, I had to retreat to lower elevations to recover.

Nights at Base Camp were cold, and although I was exhausted I couldn’t sleep through the night. There were the regular breaks due to drinking copious amounts of tea and water to stay hydrated, but there were also loud noises coming from high above.

After recovering from my bronchitis and returning to Base Camp, I began working in earnest with my mapping partner Chris Millbern. The first step was to take a goodwill tour through the sprawling camp. We would soon be traipsing through each expedition’s camp with our lidar on a tripod and flying our buzzing drone overhead.

Once we explained the work we were doing to map and better understand the high mountain environment, people were universally supportive. Pete Athans, our expedition climbing leader, who has the nickname “Mr. Everest” due to his seven summits, came with us. He had friends in all the big camps, which eased our way considerably.

As I worked my way through Base Camp, I met people from many different teams. Many of the Sherpa climbing leaders introduced themselves and offered me tea. As I chatted with them I was able to learn how the Base Camp area had changed over the past 30 years. Not only are there far more expeditions and people today, but large flat areas where it had been easy to set up camps have disappeared, replaced by a much more rugged, rubble-covered ice terrain with many “penitentes,” as the spiky ice hills and cliffs on a glacier are called.

The Sherpas also talked about how much lower the surface of the glacier was, and how much it had receded. The lowering is far more pronounced than horizontal retreat in steep-sided alpine valleys. These anecdotes reinforced the record of glacial change recorded in satellite imagery. The data we collected during our expedition allows us to more precisely determine how the glaciers have changed, and established a very accurate baseline of the glacier’s extent in 2019. Additionally, the data we have collected will enable better predictions of how the glacier will change in the future under different global warming scenarios.

Utilizing the latest Lidar equipment, we were able to collect 2-5cm resolution 3D data for the entire Khumbu Glacier and its adjacent mountain walls and moraines (the piles of rock and dirt that are left by a glacier when it recedes), an area of over 65 square kilometers. The helicopter-based equipment included Lidar and megapixel cameras that collected visible and infrared imagery.

Point clouds from the Lidar, and digital terrain models from the photographic imagery, combine to produce the highest-resolution ever model of a complete Himalayan glacier. This model includes the lateral and terminal moraines as well as the mountain walls adjacent to the glacier.

The 3D model of the Khumbu Glacier provides important data for meteorologists as well. Our meteorologic team, who set up the the  world's highest weather station , can use data on daily changes in snow and ice to test models of how temperature and environmental conditions affect melt rates and other changes to the snow and ice.

The high-mountain glaciers of the Hindu Kush-Himalaya feed many of the largest and most important river systems in Asia. Although precipitation throughout each river basin is important, the water stored as high alpine ice and snow in these "water towers" is a critical component to the  water needs downstream —for human household, agricultural, and industrial use, and the needs of the natural ecosystem.

The Perpetual Planet Extreme Expedition to Everest is contributing state-of-the-art data and trailblazing scientific research that will enhance our knowledge of the changes to the glaciers, snow, and ice of the highest mountains in the world—the water towers serving more than a billion people.

Information from this expedition will contribute to better understanding of past and current environmental conditions, and help to better predict how the mountain environments and downstream areas will change in years to come. Better predictions can enable better adaptations for the human and natural communities that rely on the water from the high mountains.