Firefighters are embarking on an ambitious experiment to stamp out blazes deep in the Alaskan wilderness as a way to avert carbon emissions in what experts say is a seismic shift in thinking in modern wildfire management that has traditionally focused only on fires that threaten human life, property or commercial interests. In what several scientists said is a first for the United States or Canada, the Alaska Fire Service has agreed to sometimes tackle flames in selected areas of the remote Yukon Flats National Wildlife Refuge that do not threaten people but could trigger the thawing of the region’s ancient, carbon-rich permafrost. The experiment is so far only theoretical — after an unusually quiet Alaska fire season, Yukon Flats Refuge Manager Jimmy Fox said. The approach also has its skeptics, who believe limited firefighting resources should be devoted exclusively to wildfires that could encroach on human development.