Encore: Work that matters in the second half of life.

New York Times columnist Nicholas Kristof, long a champion of what he calls “bright-eyed young people” trying to save the world, gives a full-throated endorsement of encore careers in his July 21 column.

Kristof highlights two aging baby boomers who are spearheading the fight against malaria. One, Nobel Prize winner Peter Agre, gave up “a fancy administrative position” and took a substantial pay cut to head the Malaria Research Institute at Johns Hopkins. “It wasn’t a matter of being a Mother Teresa,” Dr. Agre told Kristof. “It was a matter of, ‘Boy, that sounds like fun!”

The other, Rob Mather, left a career as a management consultant to found Against Malaria, helping families buy bed nets to protect against mosquitoes. “Mr. Mather’s work has resulted in hundreds of thousands of bed nets being shipped abroad to save lives so far,” Kristof writes, “all of which he finds rather more fulfilling than his previous, more lucrative career.”

“If we boomers decide to use our retirement to change the world, rather than our golf game, our dodderdom will have consequences for society every bit as profound as our youth did,” Kristoff writes.

Phrases like “dodderdom,” and even the headline of the column, “Geezers Doing Good,” may put some people off, but they also serve to defuse the issue of age, by poking fun and stripping off the cloak of euphemisms. (What do you think? Post a comment.)

Of course, Kristof can’t avoid a mention of Bill Gates, who has left his job at Microsoft to devote full-time to his foundation, tackling challenges in global health, education and poverty reduction.

“We often think of those trying to save the world as bright-eyed young people, but Mr. Gates is part of a booming trend: the “encore career” as a substitute for retirement,” Kristof writes. “Definitions are still in flux, but an encore career typically aims to provide a dose of personal satisfaction by ‘giving back.’”

If more people take on encore careers, he says, “The boomers who arrived on the scene by igniting a sexual revolution could leave by staging a give-back revolution. Boomers just may be remembered more for what they did in their 60s than for what they did in the Sixties.”