Facebook's campus on the shoreline of San Francisco Bay is at risk from rising sea levels. So is a nearby low-income community. That's raising questions about who should be paying for climate change. Taxpayers or private landowners (in this case, some of the world's largest tech companies) with waterfront property? NPR climate correspondent Lauren Sommer explains in the first of two episodes.For more on this story, including pictures and videos, click here. Email the show at shortwave@npr.org.