Warner was born in Modesto, California, in the heart of the rich agricultural breadbasket of the nation.  The son of second generation immigrants from Italy and Nova Scotia, Warner embraced different cultures early, and his curiosity often led to conflict.   He ran away from home as a teenager, staying away only briefly the first time, and still graduating from San Francisco's Balboa High School.  

He left home at seventeen and journeyed to the coastal village of Mendocino in the mid-1950s.  This small town on the northwest coast of California had an economy based in timber and fishing.   The counter-culture movement of the hippies would one day transform the village, and ultimately be the kernel that formed a world recognized center of painters, sculptors, and other artists.  But in the 1950s, no artists had yet discovered the village, and life was very simple in a town with wooden sidewalks and a piercing 12 noon whistle at the fire station.  Fresh salmon, crab, abalone, and rock cod were plentiful, and could be caught with ease.  

In Mendocino in the 1950s, tenuous connections to the rest of the world relied on winding and frequently washed out roads to the interior valleys.  This life on the edge of rough wilderness starting in Mendocino would mark Warner's career.  

Warner became involved in tournament chess, playing in the first Arthur Stamer Invitational Tournament at the Mechanics Institute.  Once he was out on his own, Warner moved to Alaska in 1963 where he stayed until 1996. During that time he worked in fisheries research, including salmon, herring, and other important commercial fish species, as well as working briefly with sea birds.  The field work took him into the remote areas of Alaska, where he often worked alone in primitive camps.  Eagles, bears, caribou, moose, and other wildlife were daily companions. Warner published his first story in 1973. 

He returned to school to receive a master's degree in interdisciplinary studies from the University of Maine in Orono in 1983.  He then switched careers from wildlife and fisheries research and moved into community college teaching, where he taught courses in English, composition, and literature at Kodiak College and the University of Alaska.  He continued writing short stories based on his experiences in the Alaskan back country, and also became involved in readings on National Public Radio.  He was awarded an NEA Fellowship in fiction in 1989, and an Alaska State Council on the Arts Fellowship the same year. He was short listed in the 1990 Stand International Fiction competition, where his story “Journal from the Bay of Islands” was published. “Islands” was the longest work of fiction ever published in that venerable literary journal up to that time.

He took early retirement and began writing fulltime.  Warner moved to Washington state in 1996, residing along the Puget Sound in Port Angeles, a small town with a busy ferry connection to Victoria and Vancouver Island, British Columbia. Port Angeles is nestled between the Strait of Juan de Fuca and the Olympic Mountains, located in Clallam County on the North Olympic Peninsula of Washington State. For nearly ten years, Warner (along with numerous chickens, ducks, and geese) lived in the outskirts of Port Angeles, working on his writing. Twice his scripts were short listed in the Nicholl Screenwriting Competition, American Academy of Motion Pictures, finishing in 2002 in the top 20 out of 5500 entries. Collections of his short stories have appeared in 1978 (In the Islands of the Four Mountains and other stories) and in 1997 (In Memory of Hawks, and other Stories from Alaska). His stories have appeared in anthologies alongside William Kittridge, Tobias Wolf, and Raymond Carver. In 2002, his first novel Wagner, Descending: The Wrath of the Salmon Queen was published by Pleasure Boat Studio.   In 2006, Warner moved to Hawaii to conduct additional research on a book set during World War II, and dealing with people who lived on Attu Island at the tip of Alaska before and during the war. His 2007 historical novel The War Journal of Lila Ann Smith is based on much research as well as interviews with many of the survivors of the invasion. Warner had also earlier produced a radio program based on the event for Alaska Public Radio.  

In 2008, Warner returned to the mainland, living south of Seattle in Fife, Washington.  In 2009, Pleasure Boat Studio published Crossing the Water, a collection of two trilogies set in Alaska then Hawaii. Warner continues to publish stories both in the U.S. and abroad, and also is an accomplished harmonica player, often giving lessons to aspiring harmonica students. 

Warner currently resides in Port Haddlock, Washington..