Claire Harbage

Photographer Kari Wehrs was shocked when she found out four years ago that her 61-year-old mother had started carrying a handgun for self-protection.

Her family never had guns when she was growing up in a midsize Minnesota town. Wehrs' mother said no particular incident had sparked her decision.

Massive stands of silvery trees rise skeletally out of saltwater marshes at the edges of the Chesapeake and Delaware bays, a significant part of the coastlines of Virginia, Maryland, Delaware and New Jersey. A few dead or dying leaves cling to the trees' branches, but mostly, they are bare.

In contrast, lush forests spread out behind them, trees robed in green leaves and pine needles, still brown with bark, coated with their elegant summer colors.

Mongolia is changing. Rivers are dry. Pastureland is giving way to mines. And wintertime smog obscures the famed blue sky. How did Mongolia get here? It's a story of internal migration and economic transformation in an era of climate change.

Explore the visual narrative at https://apps.npr.org/mongolia/

The quiet of the late-winter morning is interrupted by a staccato of gunshots.

"Military drills," shrugs Kim Seung-ho, 58, the director of the DMZ Ecology Research Institute, a nonprofit organization that does research on the wildlife in the Demilitarized Zone, or DMZ, which is the border area between North and South Korea. A thick blanket of fog seeps over the forested hills on this late-winter morning as Kim stands, searching the horizon for birds, on the bank of the Imjin River just north of Paju, South Korea.

Photographer Chloe Dewe Mathews' newest book, Caspian: The Elements, takes the reader on a meandering journey through oil-rich central Asia following traces of natural elements such as fire, gas, salt and water in people's everyday lives. Her images work as small, fascinating stories about how the region's residents interact with their environment in surprising ways.

Editor's note: This story was updated on Dec. 3.

On an average day at the National Butterfly Center, a 100-acre wildlife center and botanical garden in South Texas, visitors can see 100 different species and as many as 200,000 individual butterflies.

The center also sits directly in the path of the Trump administration's proposed border wall.