Correction: Correction: An earlier version of this article incorrectly reported the name and description of the firm that maintains The Carbon Underground 200. It is Fossil Free Indexes, a research and investment firm. The article has been corrected.

A dragline excavator moves rocks above a coal seam at the Spring Creek Mine in Decker, Mont. (Matthew Brown/Associated Press)

Montgomery County’s employee pension fund would be ordered to divest an estimated $65 million in stock that it holds in fossil-fuel companies under legislation proposed by County Council members Roger Berliner and Nancy Navarro.

The holdings represent a tiny fraction of the county’s $4 billion investment portfolio. But Berliner (D-Potomac-Bethesda) and Navarro (D-Mid-County) contend that the council has a moral and political obligation to shed its stake in oil, natural gas and coal companies.

“Climate change is an existential threat to the entire planet,” the two members said Tuesday in a memo to council colleagues. “Its correlation with the companies principally responsible for creating climate change is direct.”

After passing numerous bills and resolutions over the years that limit carbon emissions and promote clean energy, they said, the county “should not be investing in the very companies that undermine our commitment to sustainability.”

If the measure passes, Montgomery County would become one of the largest localities in the nation to join the divestment movement organized by, the grass-roots organizing group founded by former New Yorker magazine writer Bill McKibben. A local affiliate, 350MoCo, has lobbied the council to address the issue.

The number 350 represents the level of atmospheric carbon dioxide many scientists say the planet must reach to avoid the most dire consequences of climate change. The level is now an estimated 400 parts per million.

Like Montgomery County, the divesting jurisdictions are mostly liberal strongholds such as Minneapolis; Portland, Ore.; Seattle; San Francisco; and a selection of college towns. They have pledged to sell all or part of the holdings in their pension funds. The District of Columbia Retirement Board has also eliminated about $20 million in fossil-fuel investments — less than 1 percent of its total portfolio — over the past couple of years.

Critics say that divestment has little or no impact on the companies or on climate change and that it only politicizes the management of public employee retirement funds. The county’s pension fund is overseen by a 13-member Board of Investment Trustees, appointed by the council and the county executive.

The fund holds stock in 65 ­fossil-fuel companies listed on the Carbon Underground 200, an index of the top 100 publicly traded coal and 100 oil and gas companies ranked by potential carbon emissions in their reserves. The list is maintained by Fossil Free Indexes, a research and investment firm.

Berliner and Navarro said that current low stock prices should make it relatively easy for the board to divest. “Given the strength of portfolios without fossil fuels, and the relatively poor performance of fossil fuel stocks we are confident that the Board will be able to harmonize our county’s values with its fiduciary duties,” they said in the memo.

The bill gives the board five years to sell the stocks and include an “off-ramp” provision that allows for retention of fossil-fuel investments if it can demonstrate that divestment would reduce the return of the portfolio.

Board of Investment Chair Gino Renne said in an interview Tuesday that he was inclined to favor divestment but needed to see details of the plan.

“Sometimes your personal beliefs are in conflict with your fiduciary obligations,” said Renne, who is also president of the United Food and Commercial Workers Local 1994, which represents about 5,000 county workers.

As long as the board has the option to hang on to the stocks, he said, he would probably support the bill.

“We can move in that direction, presuming that doing so won’t have a negative impact on investment yield,” Renne said.

The bill will be scheduled for a hearing before the council’s Committee on Government Operations and Fiscal Policy, which Navarro chairs.