WASHINGTON, May 20 (Reuters) - The United States must double or quadruple the rate at which it thins and removes dead wood from its forests to reduce the threat of wildfires that have become more frequent and severe due to climate change, the Biden administration said on Thursday.

The call for a more ambitious forest management program comes after a record wildfire season in 2020 that burned more than 10 million acres, nearly half of which were on lands owned by the U.S. Forest Service.

The yearly blazes have grown worse in recent years because global warming has brought warmer temperatures and periods of drought, and also because decades of lax forest treatment practices have led to a build-up of dead trees and brush.

"Forest Service and other research scientists have determined that this current level of treatment is not enough to keep pace with the scale and scope of the wildfire problem," the U.S. Department of Agriculture (USDA) said in a document laying out the department's climate change strategy.

The USDA, which manages the 193 million acres of Forest Service land, said forest treatment rates need to rise by between two- and four-fold. That would result in an additional 50 million acres of federal, tribal and private lands, primarily in Western U.S. states, being treated in the next 19 years, it said.

The Forest Service treated 2.65 million acres in 2020 to reduce the dead wood that fuels wildfire.

The agency also said it would increase reforestation efforts to help boost forests' ability to sequester carbon dioxide. Forests now sequester the equivalent of 14% of U.S. carbon dioxide emissions, the report said, a level which the agency said could increase by 20%.

Strategies to remove carbon from the atmosphere are regarded as critical to meeting U.S. President Joe Biden’s goal to decarbonize the U.S. economy by 2050.