WASHINGTON — Joseph R. Biden Jr. assumed the presidency on Wednesday, bringing an expansive team of climate change experts to staff a White House that is preparing to focus on global warming in a way no other administration has done before.
Mr. Biden enters office with the largest team ever assembled inside the White House to tackle global warming and has installed policy experts at the State Department as well as the National Security Council, the president’s top advisory body for all foreign policy decisions. The Treasury Department, the Transportation Department and the office of Vice President Kamala Harris all will have dedicated climate policy staff, with more hires expected in the coming days throughout the government.
He has vowed to move quickly. In addition to rejoining the Paris Agreement on Wednesday, the new president intends to cancel the Keystone XL pipeline permit in his first hours in office. In the following days, people with knowledge of the team’s plans said, Mr. Biden will issue a series of executive orders that start the process of rolling back some of the Trump administration’s most debated environmental decisions — such as restricting the science that can be used to create new air and water protections — and lay the groundwork for ambitious new policies.
An executive order aimed at re-establishing scientific integrity in federal decision-making is high on the list, after four years of an administration that mocked or belittled the established science of climate change, elevated discredited climate denial studies and sidelined scientists who work on the issue. He also is expected to begin the process of forcing agencies to calculate the costs that carbon dioxide emissions impose upon society. By raising the costs of climate change, the Biden administration hopes to change cost-benefit analyses in a way that makes strong regulatory action more economically appealing and less susceptible to negative court rulings, two people familiar with the plans said.
Even fossil fuel advocates said they have been surprised by the intensity of the Biden team’s focus on climate change.
“I underestimated the level of seriousness that these guys had about this,” said Thomas J. Pyle, the president of the Institute for Energy Research, an organization that supports the expanded use of gas, oil and coal.
“They are devoting a lot of personnel to the issue set, and I think that just emphasizes the level of influence that the greens have on the Democratic Party,” Mr. Pyle said.
As with other policy areas, when it comes to climate policy the incoming president has relied heavily on old hands from the Obama administration.
He selected Gina McCarthy, who led the Environmental Protection Agency in the Obama administration, start up a new White House office on climate policy. Ali Zaidi, a former top energy official in the Obama administration’s White House Office of Management and Budget, will be Ms. McCarthy’s deputy.
Last week Mr. Biden appointed David Hayes, who served as the deputy interior secretary in both the Obama and Clinton administrations, to be a special assistant to the president for climate policy. Former Secretary of State John Kerry will serve as Mr. Biden’s international climate envoy.
In the coming days, two people with knowledge of new hires said, Mr. Biden is expected to announce several additions to Mr. Kerry’s team. They will include Jonathan Pershing, who served as the State Department special envoy for climate change under President Obama; Sue Biniaz, a former top climate lawyer for the State Department across multiple administrations who played a key role in drafting the Paris Agreement; and Leonardo Martinez-Diaz, who served as the deputy assistant secretary of the Treasury Department for energy and environment under Mr. Obama. Rick Duke, who served as a special assistant to Mr. Obama on climate change also is in talks to join Mr. Kerry’s team, the two people confirmed.
But Mr. Biden also has reached into the worlds of clean energy development, the youth climate movement and environmental justice activism for key deputy-level positions.
Cecilia Martinez, a prominent advocate for addressing racial inequality in environmental policies, will serve as senior director for environmental justice at the Council on Environmental Quality. Tarak Shah, a former Energy Department official under Mr. Obama is also expected to be chief of staff to Jennifer Granholm, the nominee to be Energy Secretary.
The mix of expertise was applauded by moderate Democrats as well as the liberal wing of the climate movement, which has been critical of some of the incoming president’s policy positions and personnel choices.
“The picks are genuinely encouraging,” said Evan Weber, political director of the Sunrise Movement, a group that pressed for the Green New Deal, an expansive suite of climate and economic policies that Mr. Biden has not embraced in full.
“These are serious advocates who understand the policy details, who have connections to the climate movement and the environmental justice movement,” Mr. Weber said.
Paul Bledsoe, a former climate adviser in the Clinton White House, said the picks showed the White House was becoming the “domestic nerve center” for climate change in the Biden administration.
Mr. Bledsoe said Mr. Hayes in particular, with whom he worked in the Interior Department in the 1990s, “has an encyclopedic knowledge of the connection between public lands and climate,” and called him “the perfect complement” to Ms. McCarthy, whose expertise is in mitigating emissions through clean air and water laws.
Working with Ms. McCarthy and Mr. Hayes in the White House Office of Climate Policy will be Sonia Aggarwal, who co-founded the San Francisco-based energy and environmental policy firm Energy Innovation. There, Ms. Aggarwal helped develop a model called the Energy Policy Simulator to help policymakers drill down on specific clean energy policies and measure in real time the costs and emissions impacts of various plans. She will serve as senior adviser for climate policy and innovation.
One of Ms. Aggarwal’s areas of expertise is the development of a clean energy standard — that is, the percentage of non-fossil fuel sources that utilities must reach in their power generation and sales. By setting a standard without a source-by-source prescription, the policy is supposed to allow businesses and utilities to determine the most efficient way of meeting the targets. With the Senate now controlled by Democrats, even with a razor thin margin, the possibility of passing such a mandate could be within reach.
Maggie Thomas, who served in climate adviser roles in the presidential campaigns of Governor Jay Inslee of Washington and Senator Elizabeth Warren of Massachusetts, will serve as Ms. McCarthy’s chief of staff.
Jahi Wise, who was a policy director for the Coalition for Green Capital, a nonprofit group that works to drive investment in clean energy, will be a senior adviser for climate policy and finance.
The expansive White House team, which is not subject to Senate confirmation, has provoked consternation among Republicans. Senator John Barrasso of Wyoming, who will be the top Republican on the Senate Energy Committee, said he believed increased energy innovation and “not the appointment of countless unchecked czars” would be best for both the economy and the environment.
James P. Pfiffner, an emeritus professor of public policy at George Mason University and an expert on the presidency, noted that presidents have increasingly centralized control in the White House by creating special positions around policies of high importance, with mixed results.
A new White House climate office staffed with at least five people is a lot, he said, and a White House “czar” like Ms. McCarthy would have her challenges.
“White House staffers do not have the authority to make decisions on spending or personnel,” he said. “Certainly, they can be powerful, but only to the extent that their policy area is of primary importance to the president.”