Wildfires had emitted up to 7 percent of the total greenhouse gases in the U.S. state of California in the first decade of this century, U.S. researchers said Thursday.

While forests and vegetation on the wildlands in California stored an estimated 850 million tons of carbon in 2010, they emitted over 69 million tons of carbon from 2001 through 2010, Patrick Gonzalez, a climate change scientist with the National Park Service, told Xinhua.

Two-thirds of the carbon loss during the period were caused by fires that burned 6 percent of the area of wildlands in the Golden State on the U.S. west coast, he said.

"Annual carbon losses from forests and wildlands in California represent as much as 5 to 7 percent of state carbon emissions from all sectors and are caused mainly due to unnatural vegetation build-up," added Gonzalez, lead author of a study in this month's journal Forest Ecology and Management.

Human beings have been trying to prevent fires from breaking out in wooded areas for over a century, mainly thanks to the advent of modern firefighting techniques. However, new studies have shown that naturally occurring fires can actually be beneficial for the ecosystem, since dead vegetation hinders tree growth and traps carbon gas instead of releasing it.

"This is something common to every wooded area that has a similar ecosystem as California's. A century of fire suppression has created abundant build-up, storing carbon," Gonzalez said. Now, whenever there is a fire, a tremendous amount of stored carbon gas is let out, contributing to the greenhouse effect.

A wildfire that destroys vegetation and releases carbon gas could spell trouble for California's goals to curb climate change. In 2006, the state passed a law to reduce greenhouse gases to 1990 levels, or 30 percent less than nowadays, by 2020 and bring them further down to 80 percent of 1990 levels by 2050.

The information available at the time the bill was passed may have underestimated the release of carbon through landmass conversions and wildfires, which are projected to increase in intensity in western United States due to climate change.

"Projections of more wildfires in the West mean that we need to account for this source of carbon emissions," said John Battles, co-author of the study at University of California at Berkeley's Department of Environmental Science, Policy and Management. And meeting the state's greenhouse gas targets might require a reconsideration of wildland management policies.

"I think our research really highlights the need to respect the natural role of fire in the ecosystem, which applies not only to California's woodlands, but anywhere where there is vegetation," Gonzalez said.

The analysis is based on 2001-2010 data from multiple public sources, including the U.S. Department of Agriculture's Forest Inventory and Assessment Program, according to a UC Berkeley news release.