A decade ago, I was feeling pretty pessimistic about climate change. The politics of mitigating global warming just seemed impossible: asking people to make sacrifices, or countries to slow their development, and delay dreams of better, more prosperous lives. But the world today looks different. The costs of solar and wind power have plummeted. Same for electric batteries. And a new politics is starting to take hold: that maybe we can invest and invent and build our way out of this crisis. But some very hard problems remain. Chief among them? Cows. Hannah Ritchie is the deputy editor and lead researcher at Our World in Data and the author of “Not the End of the World: How We Can Be the First Generation to Build a Sustainable Planet.” She’s pored over the data on this question and has come away more optimistic than many. “It’s just not true that we’ve had these solutions just sitting there ready to build for decades and decades, and we just haven’t done anything,” she told me. “We’re in a fundamentally different position going forward.” In this conversation, we discuss whether sustainability without sacrifice is truly possible. How much progress have we made so far? What gives her the most hope? And what are the biggest obstacles? Mentioned: “What was the death toll from Chernobyl and Fukushima?” by Hannah Ritchie “Reducing food’s environmental impacts through producers and consumers” by Joseph Poore and Thomas Nemecek “Future demand for electricity generation materials under different climate mitigation scenarios” by Seaver Wang, Zeke Hausfather et al. Book Recommendations: Factfulness by Hans Rosling Possible by Chris Goodall Range by David Epstein Thoughts? Guest suggestions? Email us at [email protected]. You can find transcripts (posted midday) and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast. Book recommendations from all our guests are listed at https://www.nytimes.com/article/ezra-klein-show-book-recs. This episode of “The Ezra Klein Show” was produced by Rollin Hu. Fact-checking by Michelle Harris, with Mary Marge Locker and Kate Sinclair. Our senior engineer is Jeff Geld, with additional mixing by Isaac Jones. Our senior editor is Claire Gordon. The show’s production team also includes Annie Galvin, Kristin Lin and Aman Sahota. Original music by Isaac Jones. Audience strategy by Kristina Samulewski and Shannon Busta. The executive producer of New York Times Opinion Audio is Annie-Rose Strasser. Special thanks to Sonia Herrero.