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Dawn began to glow on the horizon as Andrew Towne slowly climbed the last 20 feet to stand, literally, at the top of the world.

That moment, at the summit of Mount Everest, 29,029 feet, came at 4:35 a.m. Thursday. It lasted just 15 minutes, time for a few breaths and a few photos, before Towne and his sherpa began the treacherous 8,000-foot descent to a place they could finally rest.

By Sunday afternoon, Towne, 35, of Minneapolis, already was back in Washington, D.C., for the annual meeting of Youth for Understanding (YFU), a group that first inspired him to travel and explore when he was in high school in Grand Forks, N.D.

The Everest summit was the culmination of a quest to climb the tallest mountain on each of the seven continents.

Towne recounted his seven weeks on the mountain in a series of blogs on the YFU website and in a phone interview on Sunday:

"By the time the summit loomed in front of me, I really didn't care about anything other than getting to a place where I could take a nap without dying," Towne wrote. "I absent-mindedly continued putting one foot in front of the other until I was standing on top. I no longer cared about food or water. … I was thinking only about my fingers and toes (and making sure I could feel them) and on the focus I would need to descend safely."

There was no rush of adrenaline, no immediate sense of elation at the summit, Towne said Sunday. There was only exhaustion and struggling to breathe. It was only later, at lower altitudes, that he realized it wasn't exhaustion but hypoxia from a lack of oxygen.

"We wish we had taken more photos, but at the time photos were the last thing you're thinking about," he said.

Towne's climb was a fund­raiser for YFU, an international student exchange program dedicated to cross-cultural understanding. He exceeded his goal of $25,000; some of that money is specifically earmarked to provide scholarships to Minnesota and North Dakota students who couldn't otherwise take part.

Towne's trip to Everest was a homecoming of sorts. He was at base camp on April 25, 2015, when a magnitude-7.8 earthquake devastated Nepal. The ensuing avalanche killed 36 people at base camp. Towne and the rest of his teammates survived physically unharmed. In all of Nepal, nearly 9,000 people were killed and nearly 22,000 injured.

Towne helped those he could on the mountain and stopped to assist families in a hard-hit sherpa village while hiking back to Kathmandu that year. He was determined to try to conquer the mountain again.

Returning this year on April 6, he said, "I was encouraged to see how strongly Kathmandu and the Khumbu Valley had rebounded."

After making the slow, 30-mile hike to base camp, Towne had vivid flashbacks of the 2015 devastation.

"I looked around and I identified the exact section that served as a funnel for the rock and ice that rained down on base camp, the exact geographical feature that killed so many people," he said. "When I saw the Buddhist altar at the center of camp, I saw a vision of stacking bodies in front of the altar, which is what we did for a half-day after the earthquake."

Towne's mental energy, though, needed to be on the climb. Rotations to acclimate to increasingly higher altitudes took five to seven days apiece, first at 19,500 feet, then 21,000 feet, then 24,000 feet, then the summit. At the higher camps, sleep comes in 20-minute bursts, he said.

On May 4, Towne wrote in his blog that he and his sherpa guide were 4,000 feet below Ueli Steck when the world-famous Swiss mountaineer fell to his death.

"While Ueli was climbing and preparing for much riskier routes than we are, the tragedy still drove home the dangers of this place," Towne wrote. "I reaffirm my commitment to safety during this climb, even as I grieve the death of the man who was so full of life when we met him … just a couple of weeks ago."

He wrote of seeing the body of a dead climber lying in the snow as they tackled the last leg before the summit.

He wrote of laying his sleeping pad in the snow and hoping to catch a breeze when the sun's rays turned the mountain into a solar oven during daylight hours. Other times the temperatures were as low as 25-below Celsius (13-below Fahrenheit).

Then it was time for the summit.

Towne said Sunday that he and his teammates set off at 10 p.m. Wednesday. It was a new moon and pitch black, but headlamps helped guide them. They climbed up at night so they could climb down during daylight hours. Each step required stopping to take three or four breaths.

"I would say when I look back, I have a profound respect for just what it means to climb at those incredible altitudes," he said. "I get it now. If you take more than one step for every three or four breaths, your body starts screaming.

"The temptation and desire to rest only gets bigger," he said. "Basically you get to a point where you stop feeling the cold and only feel the exhaustion, and that's a dangerous point."

The descent is, in many ways, more stressful than the ascent. "You're more tired, moving faster and it's easier for you to misplace your foot," he said.

Towne and his team arrived in Camp 2 about 4 p.m. Thursday after 18 hours of climbing. The next day, they were at base camp, where they celebrated with a Coca-Cola.

The extra oxygen at sea level feels great, Towne said Sunday. "I should be feeling on Cloud 9 for up to a month," he said. "I plan to go out and do as much running as I can while I've got this souped up body."

He'll return to his North Loop apartment and job with Boston Consulting Group. What comes next? "I'm leaning toward martial arts, ballroom dancing or orienteering."

Pat Pheifer • 612-673-7252