Correction: An earlier version of this article mischaracterized the amount of carbon emissions in the region’s atmosphere. The annual amount of greenhouse gases in Fairfax and surrounding jurisdictions is measured in millions of metric tons, and not millions of metric tons per capita. The article has been corrected.

Nearly a decade after the launch of a national campaign to dramatically reduce greenhouse gas carbon emissions, the progress of the effort’s chief advocate in the Washington region is murky, environmental groups say.

In 2007, Fairfax County spearheaded a “Cool Counties” initiative with the Sierra Club to push local communities to reduce their carbon emissions by 80 percent before 2050.

Since then, municipalities in the region have been duly reporting their successes under that initiative and a similar one called “Cool Cities,” with the District and Arlington and Montgomery counties all showing reductions in greenhouse gases.

Virginia’s largest jurisdiction, however, has kept its residents guessing about its progress — and Board of Supervisors Chairman Sharon Bulova (D) says the county needs to do better.

Environmental groups say the county’s enthusiasm for climate initiatives appeared to wane during the recession that began in 2008, weakening tax revenue and depleting funds needed for a variety of services.

Since 2011, Fairfax has followed through on just two of 24 climate-oriented recommendations made by an Environmental Advisory Council appointed by the board of supervisors, including establishing a greenhouse gas reporting system for individual buildings so that environmental groups can pressure property owners to keep emissions down. A similar system already exists for Fairfax County public school buildings.

The county has also released conflicting, out-of-date information about its efforts to reduce greenhouse gas emissions. Critics say the government hasn’t done enough to pressure area businesses to help reduce pollution in a community with 1.1 million residents and some of the nation’s most heavily traveled roads.

Bulova said she plans to convene an environmental task force of community and business leaders in hopes of re-energizing ­private-sector efforts to combat climate change. A similar task force disbanded in 2010 after about a year of work.

“I would say that we’ve made some significant progress,” Bulova said. “But when you look at our website, we probably should include fresher information and describe better where we are.”

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As part of the regional initiative, jurisdictions are aiming to reduce emissions at least 20 percent from 2005 levels by 2020.

Last year, Arlington County reported that its greenhouse gas emissions were down 15 percent, to 2.3 million metric tons, since 2005. Montgomery County showed an 11 percent drop during the same period, to about 6.5 million metric tons. In the District, greenhouse gas emissions were down by 23 percent in 2013, the most recent year reported.

Fairfax officials haven’t monitored their emissions as closely. A “Community Greenhouse Gas Inventory” posted on the county website is dated 2013 and shows emissions increasing 3 percent — to 12.2 million metric tons — between 2006 and 2010.

After environmental groups complained about the available information, the county this month began circulating data that shows a 10 percent reduction in greenhouse gases — to 13.1 million metric tons — between 2005 and 2012. That report includes environmental improvements made at Washington Dulles International Airport. The 2013 report did not include Dulles, which is why the emissions output was lower, Fairfax officials said.

They said the public should focus on regionwide data recorded by the Metropolitan Council of Governments, which they called a more accurate reflection of the regional challenges on climate change. That entity shows a half-percent drop in greenhouse gases throughout the region through 2012 — to nearly 69 million metric tons — a measurement that factors in air travel and other aspects of life in the area that aren’t specific to one community.

But environmental advocates said the region’s largest jurisdiction should be putting out its own up-to-date figures.

“If you can’t measure it, you can’t manage it,” said Eric Goplerud, chair of the Faith Alliance for Climate Solutions. The group has criticized Fairfax for not following through on some climate-oriented initiatives — such as studying the local effects of rising sea levels — and points out that surrounding jurisdictions have entire departments dedicated to environmental conservation while Fairfax, with 1.1 million residents and 406 square miles, has a lone “environmental coordinator” charged with overseeing green initiatives.

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“This county can be a leader by showing its commitment to reducing its greenhouse gases in its buildings and of its energy uses,” Goplerud said. “It is certainly not showing it. We have a lack of information, a lack of accountability and a lack of leadership to make it happen.”

Kambiz Agazi, the environmental coordinator, says the county has been vigilant about offsetting the impact of its large carbon footprint. Those efforts include promoting walkable, mixed-use developments in some neighborhoods and encouraging developers to use green-friendly technology in their buildings.

A federally mandated $660 million upgrade of underground water pipes in the county is geared toward reducing the flow of pollutants into tributaries of the Chesapeake Bay, and a “waste-to-energy” plant in Lorton produces enough renewable energy to fuel 80,000 homes, county officials say.

Supervisor Pat Herrity (R-Springfield), the most conservative member of the board of supervisors, lauded those efforts and dismissed the Cool Counties initiative as “hot air.”

Still, Bulova and others say that working against climate change is something the county takes seriously.

Larry Zaragoza, vice chairman of the county’s Environmental Advisory Council, said launching initiatives in a community as large and complex as Fairfax County can be a lengthy and often laborious process.

“It’s taken time to try to make sure that we have everyone on the same page and that we have a constructive path we can take in order to make progress,” Zaragoza said. “But, we’re not where we want to be. We want to do more.”