Roman Mars, host of the podcast "99 Percent Invisible," describes some of his favorite examples of clever design from his home turf in Oakland and Berkeley. Then two tour guides from London team up with Rick to recommend an ideal sightseeing week in the British capital. And poet and essayist Lisa Wells shares the insights — and optimism — she gained from interviewing a geographically and ideologically wide range of people battling climate change by improving their own communities.

• Roman Mars, author of "The 99 Percent Invisible City" (HMH-Mariner Books)
• Steven Back, London-based tour guide
• Robert Halkett, London-based tour guide   
• Lisa Wells, author of "Believers: Making a Life at the End of the World" (FSG)

• Roman Mars is the author of "The 99 Percent Invisible City" and hosts the "99 Percent Invisible" radio features and podcast from his home base in California's East Bay.
• Steven Back offers tours of London and surrounding areas.  
• Robert Halkett can be contacted for custom tours of London through the Great British Tours 2020 Facebook page.  
• The online Rick Steves guide to London includes a link to Rick's audio walking tours of the city
• Rick and the guides recommend visiting Borough Market and the adjacent Southbank Walk, and suggest Camden Market as particularly appealing to teenagers.
• Lisa Wells describes what the people she met around the country are doing to identify and address the effects of climate change, in her book, "Believers: Making a Life at the End of the World."
• A summation of the 6th Assessment Report on Climate Change around the world, which was released by the Intergovernmental Panel on Climate Change in August 2021.