Barwis was born as Merle Emmeline Stedwell in the U. S. state of Iowa on 23 December 1900. At the age of four, she emigrated with her family to Canada, living on a homestead. Their first shelter was a sod hut; she grew up on a prairie horse ranch in Saskatchewan.

A lot of Barwis’ childhood was spent on horseback, learning ranching skills and responsibilities. As a young woman, she met ranch hand Dewey Barwis at a dance, and the couple were later married. Her husband later found employment with the Canadian Pacific Railway (CPR) as a stationmaster, and they moved around the prairies with their three children.

In 1952, Barwis and her husband, him having retired, moved to the west coast of Canada to be closer to their son, settling in Sooke, British Columbia. Barwis was widowed in 1966, but regularly relished in the company of her grandchildren and great-grandchildren.

Barwis continued to do her own gardening into her 90s, and enjoyed coffee and the occasional cold bottle of beer. She moved into a retirement facility in Langford, a municipality of Victoria, British Columbia, as a centenarian.

Barwis died on 22 November 2014 at the age of 113 years, 334 days. At the time, she was the fourth-oldest person to die in Canada, and remains the oldest ever in British Columbia as of 2023.