Tim Kovar may well be the most celebrated tree climber in the world.

The founder of Oregon City's Tree Climbing Planet has led The New York Times up an 800-year-old California redwood, spent three days on an ascent for a National Geographic film shoot in Central America, and served as personal instructor for Richard Preston, author of The Wild Trees. He's dodged bee swarms in Brazil, and sought out tree-dwelling king cobras in India.

But in Atlanta, he never imagined being one of the nation's foremost tree-climbing experts.

"I was in my early 20s, still soul searching a bit, when a friend asked me to come do some work with him outside," says Kovar. "It was just a change of pace." After six months of grueling labor, an arborist friend asked if Kovar would help assist with lessons for an academy he'd begun called Tree Climbers International: "I remember thinking, tree-climbing school?"

Kovar arrived at the base of "these beautiful southern white oak trees," he says. "There must have been 20 people from the age of 6 all the way up to these two ladies who were about 75 years old. And when these ladies put on ropes and got up 25 feet to the first branch, I remember looking at them in awe, thinking that these women have not climbed a tree in over 65 years. Those 75-year-old women, I don't even know their names, were two of the biggest teachers of my life."

Kovar eventually became chief instructor of Tree Climbers International in Atlanta before helping open the first tree-climbing school west of the Rockies. In 2010, he launched Tree Climbing Planet on 150 acres of forested Clackamas County farmland.

Many students, he says, are tree-canopy researchers. But there are any number of reasons to climb a tree. "We just had a student from Washington state who's an occupational therapist, and she hopes to work with PTSD soldiers in the treetops," Kovar says. "We worked with some muscular dystrophy camps getting kids out of wheelchairs. Pretty much anyone who wants to access trees, we have a course for them."

Kovar believes that tree climbing can be a universal language. At that first climb in Atlanta 25 years ago, he says, "There was a family from Germany over near some very conservative couple talking next to this hippie chick—different political views, different philosophical beliefs —but, at that moment, everybody was getting along. Nothing but people just sharing stories about climbing trees as children. And that was where I set my compass."