The pine beetle has turned one-quarter of B.C.'s pine forests brown, and that's hurt their ability to soak up carbon dioxide. (CBC)

British Columbia's forests, often hailed as a giant sponge soaking up harmful air pollution, have become a net producer of carbon dioxide, a government reports says.

The report indicates the mountain pine beetle, which has killed millions of trees, and massive forest fires in recent years have transformed the forests from a carbon sink into a source of carbon dioxide.

The State of the Forests Report says the pine beetle epidemic appears to have peaked, but it will still take another decade before B.C. forests return to their carbon-sink status.

Forests Minister Pat Bell said the report shows government policies are supporting a sustainable forest industry.

But the B.C. Government and Service Employees Union doesn't share that view, saying the report shows budget cuts and reorganization in the Forests Ministry have severely eroded the government's ability to manage the forests.

Union president Darryl Walker is calling for a public inquiry to make recommendations to revitalize the forestry sector and restore public accountability.