"Factfulness" explores why humans are consistently wrong about common problems facing the world. Instead of making decisions based off of facts and data, humans are largely influenced by unconscious biases. The silver lining is that the world is doing better than it may seem.

The book is "very readable," Gates says. "It talks about how the world has changed, and Hans shares how he had some misperceptions, that he didn't see all the progress. It taught you how to think about news and where we're going."

Gates and his wife Melinda first became fans of Rosling's in 2006, when he gave a viral TED Talk on the same topic. When the author passed away in 2017, the couple promised to carry on his final wish.

"He simply hoped that we would promise to keep spreading the message he was so passionate about: that the world is making progress, and that policy decisions should be grounded in data," Gates shares in a blog post dedicated to Rosling.

Don't miss: Warren Buffett doesn't think college is necessary—here's how he learns

Like this story? Like CNBC Make It on Facebook!