The Sierra Club–Lancaster group is holding its fourth annual Polar Bear 5K Trail Run/Hike at 10 a.m., January 18, at Lancaster County Central Park. Race day check-in will begin at 8:30 a.m. at the park’s pavilion 22 (Kiwanis lodge).

The race route will wind through the park on well-maintained trails that include some hills. Dogs are welcome to join hikers (but not runners). Last year, more than 250 hikers and runners participated in the race, and scores of volunteers were on hand to produce the event. Proceeds from the race will support efforts to end global warming, the reason polar bears and other creatures are at risk of extinction.

Cost: $20 by Jan. 7 or $25 afterwards. Those that preregister will receive a specially designed T-shirt. For registration forms and more information, email [email protected] or visit LancasterSierraClub.org.