President-elect Joe Biden added more than a half-dozen climate staffers to his White House team Thursday, drawing from the ranks of green groups, environmental justice advocates and former Democratic administration officials to grow an inner circle that will help him try to slash the nation’s greenhouse gas emissions.

The new hires include David J. Hayes, who served as Interior deputy secretary under Presidents Bill Clinton and Barack Obama; Cecilia Martinez, a prominent environmental justice advocate based in Minneapolis who advised the transition team; and Stef Feldman, a top Biden campaign aide who helped craft his climate plan. They will work with several incoming Cabinet officials new to Biden’s orbit, including North Carolina environmental regulator Michael S. Regan, picked to run the Environmental Protection Agency, and Rep. Deb Haaland (D-N.M.), set to serve as interior secretary.

The incoming White House team — which also includes former secretary of state John F. Kerry and former EPA administrator Gina McCarthy, along with Obama administration veterans in the National Security Council and the White House Counsel’s Office — represents the most robust climate-focused group assembled in the West Wing.

“These qualified, diverse and experienced appointees share the president and vice president-elect’s view that there is no greater challenge facing our country and our world than climate change,” the transition team said in a statement. “From marshaling every part of our government, working directly with communities, and harnessing the forces of science these appointees will be instrumental in utilizing all the tools at the incoming administration’s disposal to address climate change head on.”

Biden, set to take office in less than a week, will try to execute a far-reaching strategy to embed climate action across government agencies and in legislation on Capitol Hill. He has also pledged to address the disproportionate pollution burden carried by poor and minority neighborhoods.

In a recent interview, John Podesta, who helped spearhead Obama’s second-term climate agenda as senior counselor to the president, noted that Biden has assembled more expertise on the subject than any of his predecessors. When Obama first came into office, he brought on former EPA chief Carol Browner as a senior climate adviser with just minimal staff. Podesta also operated informally during his time in the White House, using long-established relationships and his access to the president as a way to mobilize action in several departments.

Now, Podesta said, the president-elect is building out the White House staff on both the international and domestic sides. “It shows how central climate change is to Biden’s foreign and security policy, just as it is to his domestic and economic policy,” he said.

Martinez will play a major role in tackling pollution disparities as senior director for environmental justice at the White House Council on Environmental Quality (CEQ).

In an interview in July, Martinez said addressing the acute impact poor and minority neighborhoods often face from pollution needs to be “a central focus of CEQ.”

The Biden administration’s initiative on environmental justice “needs to really have some teeth to it so that the different federal agencies not only develop their plans and collaborate, but there is accountability,” she added.

Martinez is a newcomer to Washington but the new lineup includes some longtime bureaucratic veterans such as Hayes, who will serve as special assistant to the president for climate policy. Hayes spearheaded Interior’s renewable energy development plans and its efforts to address climate change impacts in the Arctic under Obama, before joining the New York School of Law’s State Energy and Environmental Impact Center. From that perch, he helped organize several legal challenges by Democratic attorneys general to the Trump administration’s deregulatory agenda.

Maggie Thomas, a former climate adviser to two of Biden’s former rivals for the presidency, Sen. Elizabeth Warren (D-Mass.) and Washington Gov. Jay Inslee (D), will serve as chief of staff in the Office of Domestic Climate Policy.

Thomas helped found a green group, Evergreen Action, which pushed Democrats to adopt pieces of Inslee’s comprehensive climate plan and lent policy chops to the burgeoning youth climate movement.

Feldman, a longtime Biden aide who started as his policy intern when he was vice president and rose to become his 2020 campaign’s policy director, will serve as deputy assistant to Biden.

During the presidential race, she helped get the buy-in of young climate activists, union leaders, environmental justice advocates and former Democratic rivals when writing Biden’s proposal to eliminate carbon pollution from the electric sector by 2035 and to spend $2 trillion over four years to boost clean energy.

Jeff Marootian, who directs the D.C. Department of Transportation, will also join the White House and help oversee future hires as special assistant to the president for climate and science agency personnel.

In recent days, Biden has also announced the return to the White House of two Obama-era officials who worked on energy and climate issues: Melanie Nakagawa, a former aide to Kerry at the State Department, and Megan Ceronsky, a former special assistant and associate counsel to Obama.

Darryl Fears contributed to this report.