Since taking office on January 20, President Joe Biden and Vice President Kamala Harris have signaled a clear commitment to science and pledged sweeping initiatives to reestablish and elevate its role in the federal government. President Biden immediately nominated scientists to some key positions and began implementing an ambitious agenda to revitalize the nation’s climate-change-mitigation efforts and get the coronavirus pandemic under control.

“This is such a hopeful moment,” says Rachel Cleetus, policy director of the Climate and Energy program at the Union of Concerned Scientists. “We’ve seen this administration hit the ground running from day one. They have signaled very clearly a return to science-based policy making and a commitment to center equity and justice in their policy missions.”

Hours after the inauguration, Biden signed an executive order to bring the U.S. back into the Paris climate accord and began the process of rolling back more than 100 of his predecessor’s other environment-threatening actions. In his first week, the president also halted the U.S.’s withdrawal from the World Health Organization, restored the White House National Security Council Directorate for Global Health Security and Biodefense, and signed more than a dozen orders related to the national COVID-19 response.

Biden also nominated or appointed scientists to leadership positions at NASA, the Environmental Protection Agency, the Department of Health and Human Services, and a slew of other agencies and his Cabinet. He nominated geneticist Eric Lander to lead the White House Office of Science and Technology Policy and elevated that role to a Cabinet-level post. In a letter to Lander, Biden outlined five key questions about the pandemic, climate change, technology, diversity and equity, and scientific integrity.

The new administration’s commitment to science is evident even in its redecorating choices. A portrait of Benjamin Franklin was quickly hung in the Oval Office to signal that science will guide the president. And a moon rock brought to Earth by Apollo 17 astronauts and loaned by NASA now sits on a bookshelf in the office, representing what a statement from the agency called “earlier generations’ ambitions and accomplishments, and support for America’s current Moon to Mars exploration approach.”

COVID-19 killed 400,000 Americans before Biden took the oath of office, and it is his administration’s most urgent challenge. The new president wasted no time attacking the deadly pandemic: On his first day, he mandated mask wearing on all federal property—later extended to airports and other forms of transportation—and encouraged all Americans to wear a mask for the next 100 days. And Biden appointed Anthony Fauci, the country’s leading infectious disease expert, to be his chief medical adviser on COVID-19. In his first week, the president invoked the Defense Production Act to ramp up production of masks and other personal protective equipment, or PPE. He announced a plan in which the Federal Emergency Management Agency would be utilized to create community vaccination centers, enhance data collection and analysis, determine how to safely reopen schools, and reinstate certain international travel restrictions. He says he also plans to increase drive-through testing, invest in rapid tests and establish a public health job corps of 100,000 Americans to do contact tracing.

Biden pledged to vaccinate 100 million people in the U.S. in his first 100 days. His predecessor had not developed any vaccination plan, making this effort a serious uphill climb. “It’s just awful, and it puts efforts way behind time line and means there will be a lot of difference between what states do,” says Eric Toner, an emergency physician and senior scholar at the Johns Hopkins Center for Health Security. Although 100 million vaccinations once sounded startlingly ambitious, “now it seems like that should be the floor,” Toner says. “We’re already doing more than a million vaccinations a day. We need to get up to about three million per day to reach the goal of having most people vaccinated by the summer.” This could be limited by how much vaccine drugmakers Moderna and Pfizer can produce and how quickly they can do so, he adds.

Combating racial and socioeconomic disparities in both vaccine access and hesitancy will be critical. Biden created a COVID-19 Health Equity Task Force and appointed Marcella Nunez-Smith, founding director of Yale University’s Equity Research and Innovation Center, as its chair. Addressing inequities requires the administration to reach out to trusted religious leaders and elected officials from disadvantaged and vulnerable groups, Toner says, noting that “it’s really important to leverage the connections that we have with people who are trusted in those communities.” In the meantime, he adds, emphasizing the vital importance of social distancing and mask wearing is key to “flattening the curve” of new infections.

Were it not for the pandemic, combating cancer might have been Biden’s key health initiative. In 2016, as vice president, he launched the National Cancer Moonshot after his son Beau Biden died of brain cancer. That program—renamed Cancer Breakthroughs 2020 in 2017—pools resources to develop new therapies for various cancers. “There’s no question that there's going to be opportunities to build on that Cancer Moonshot initiative, especially with President Biden being in the office,” says Jon Retzlaff, chief policy officer and vice president of science policy and government affairs at the American Association for Cancer Research. While Congress has provided “wonderful support” for medical research over the past six years, he adds, the White House has not provided similar backing. “There’s no question that President Biden recognizes the importance of science,” Retzlaff says. “He understands cancer research better than any president we’ve ever had.”

Despite the overarching demands of the pandemic, the Biden-Harris administration wasted no time tackling climate change as well. In addition to rejoining the Paris Agreement, the president also halted construction of the controversial Keystone XL pipeline on his first day in office and made key appointments that signal a commitment to climate-change mitigation. Former EPA administrator Gina McCarthy will hold the newly created position of White House national climate adviser. Former secretary of state John Kerry, who signed the Paris accord on behalf of the U.S., is now special presidential envoy for climate—a position Biden has elevated to the National Security Council.

On Wednesday, Biden signed executive orders to establish a White House Office of Domestic Climate Policy and a National Climate Task Force and to direct the Department of Justice to establish an office of climate justice. Additional orders he signed that day halt the Department of the Interior from signing new oil and natural gas leases on public lands and eliminate fossil fuel subsidies. And Biden has announced plans to replace the federal government’s fleet of 650,000 vehicles with electric models.

Much of the previous administration’s damage to climate and environmental policies came via executive orders and can be undone with the stroke of a pen. But dozens of regulations will not be reversed as easily, says Joseph Aldy, an economist at Harvard University’s John F. Kennedy School of Government, who served as then-president Barack Obama’s special assistant for energy and the environment from 2009 to 2010. The new administration will have to present evidence for why a rule should be rescinded, and it must then take public comment, he explains. “Some things may move faster than anticipated because we just had a federal court topple the Affordable Clean Energy Rule,” Aldy notes. “That makes it a little bit easier to move forward on power sector regulation if the Biden EPA wants to go forward and do that.”

That action seems likely. During his presidential campaign, Biden pledged to conduct a massive overhaul of how the country produces energy, calling for 100 percent clean electricity generation in the U.S. by 2035 and net-zero carbon emissions by 2050. Aldy says aggressive federal subsidies for wind and solar power that started in 2008 helped create a market that promoted innovation and drove down costs. “That makes it easier for more rapid deployment in the private sector going forward—to really push out fully in a really ambitious way on renewables,” he says. Whether Biden can fulfill his promise to invest $2 trillion in developing a clean-energy economy depends largely on how well his administration is able to work with Congress. But overall, the Biden team is moving “incredibly fast” on climate change, Aldy says. “It’s a testament to how seriously they’re taking this issue.”

Space exploration may be one area where Biden moves more slowly (despite the Oval Office moon rock). Casey Dreier, the Planetary Society’s chief advocate and senior space policy adviser, says the administration is unlikely to continue the National Space Council, an intermittently operating body within the executive branch. Landing American astronauts on the moon by 2024, the goal of NASA’s Artemis program, is also unlikely. “There’s almost no way that can happen at this point,” Dreier says. “NASA didn’t get the funding it needed [in 2020] to even have a chance to reach that date.” But international partners have already signed on to Artemis and started their own programs to participate—so Artemis will likely be retooled rather than scrapped, says Brian Weeden, a former officer in the U.S. Air Force with a focus on space security and director of program planning at Secure World Foundation.

The military’s new Space Force was created by an act of Congress and will likely remain, Weeden says. “We’re creating a cadre of space experts within the military, fixing challenges with space acquisitions programs and better implementing a way to deal with increasing threats to space systems,” he says.

One of the few indicators of where Biden’s space policy might go—a 2020 Democratic Party Platform proposal to use Earth observation programs at NASA and the National Oceanic and Atmospheric Administration to “better understand how climate change is impacting our home planet”—suggests a terrestrial focus. NASA’s Earth observation platforms “provide a lot of really valuable data for understanding Earth as a system,” Dreier says, and climate change remains one of the administration’s top scientific challenges.

“Biden will see NASA as more science-focused and less symbolic of nationalism” than the last administration, Dreier says. “It’s going to be seen as and used for a science opportunity rather than symbol of U.S. power.”