Somewhere west of Washington — somewhere in that vast expanse of this Manifestly Destined nation of ours — a woman asked Dave Goodrich why he had decided to ride his bicycle from the Atlantic to the Pacific.

She worked at a motel he had checked into that night after a hard day in the saddle: 60 miles or more battling head winds atop his Trek bike. Dave explained that he was a scientist from Rockville, freshly retired from a 36-year career at the National Oceanic and Atmospheric Administration, where he had overseen programs to study climate change.

That’s why he was riding, Dave said. To educate people about the threats of man-made global warming, stopping whenever he could to talk to school groups and service clubs.

“She said, ‘Do you know Al Gore?’ ” Dave remembered. “I said, ‘Well, no. I’ve heard him speak.’ ”

That’s when Dave realized that many people can’t think of climate change without thinking of the former vice president — “and he is such a polarizing figure in certain places. I had the sense the reaction to climate change was the reaction to Al Gore.”

Dave Goodrich stops at the summit of McKenzie Pass in Oregon in the lava fields, just before descending into the forests of the western Cascades. (Courtesy of Dave Goodrich)

Maybe now for a few people stretched out along the blue highways he traveled, the reaction is to Dave Goodrich. Perhaps a few people were convinced by his cogent argument that there really is no debate in scientific circles about this issue.

“I think what I was trying to say was that climate change isn’t this thing that’s going to happen in 100 years, that it’s happening now and that the things that people do are largely responsible for the long-term trends,” he said.

Weather isn’t the same thing as climate, of course, but as Dave rode west he couldn’t help but think of what we’re doing to our planet — and how that affects certain 58-year-old retirees biking across the United States. In Kansas he endured day after day of 105-degree temperatures. “The state had been having them for weeks on end,” Dave said. “And that certainly wouldn’t have been normal 30 years ago. . . . There’s been that steady increase.”

As he approached the Rockies, Dave saw entire hillsides blanketed in dead trees, victims of the mountain pine beetle. “It used to be they’d have winters to 30 or 40 below, and those haven’t happened in a long time. You need winters that cold to kill the larvae.”

When he worked at NOAA, Dave was a regular bike commuter. And he’s done some long rides before, including up to New Hampshire. But this was his longest, a year in the planning. On July 24, he dipped his tire in the Pacific at Waldport, Ore., after cycling 4,209 miles over 93 days.

Dave decided not to plaster his bike with signs that read “the Global Warming Express.”

“Part of that was because of some of the places I was going,” he said. “I had no idea whether I might get run off the road.”

There was a town in Idaho whose sporting goods/hunting supply store had a stuffed coyote out front. On it was an Obama mask, and in the window were all kinds of screeds against the president. Dave did not stop to discuss greenhouse gases. “It was kind of like, ‘Yeah, I think I’ll just ride through here.’ ”

El Dorado, here we come

On Tuesday morning, the sidewalk on M Street NW near 17th was littered with the sort of hard, black plastic cases that hold expensive equipment. There were also soft-sided duffels and one long, cylindrical case. A man and woman were helping a D.C. taxi driver load everything into his cab.

They were in front of the National Geographic Society, so I wondered whether I was seeing the very beginnings of an expedition. Yes, said Katie Bauer and Darren Foster, producers at the National Geographic’s cable channel. They were embarking on a two-week trip to Colombia to shoot a program about gold.

I guess I thought they’d leave in something a little more interesting than a cab. A Land Rover loaded with extra fuel and water? A Hummer with a satellite dish? A camel train?

“You know how budgets are,” Katie said.

They were headed to National Airport. The show is to air by early next year.