Former Secretary of State and now the nation's first ever climate envoy, John Kerry, along with Biden's national climate adviser, Gina McCarthy, joined together in the White House press briefing room Wednesday ahead of Biden signing executive actions on climate change.

"This executive order establishes a White House Office of Domestic Climate Policy, and it directs everyone who works for the president to use every tool available at our disposal to solve the climate crisis. Because we're going to take a whole of government approach. We're going to power our economy with clean energy," McCarthy said.

The duo discussed the urgency of addressing climate change and the need for global intervention -- in a stark contrast with the priorities of the Trump administration.

"We could go to zero tomorrow, and the problem isn't solved. So that's why today, one week into the job, President Biden will sign this additional executive set of orders to help move us down the road, ensuring that ambitious climate action is global in scope and scale, as well as national -- here at home," Kerry said.

Kerry also detailed the plans to further the goals of the Paris Climate Agreement at another meeting in Glasgow, Scotland, in April.

Biden's top coronavirus advisers -- including Chief Medical Adviser on COVID-19 Dr. Anthony Fauci, new Centers for Disease Control and Prevention Director Dr. Rochelle Walensky and COVID-19 response coordinator Jeff Zients -- have wrapped their first public briefing on the White House's response to the coronavirus pandemic.

In contrast with the Trump administration, the Biden administration has pledged to aim for three virtual, public briefings with health experts each week in an effort to be more transparent in their response. Biden is also branding his COVID-19 response team an "equity" task force, chaired by Dr. Marcella Nunez-Smith.

In another change promised by the Biden White House, an American Sign Langauge interpreter was also present for the briefing.

After a bit of a rocky start, with Fauci and other speakers having microphone issues, the briefing proceeded for nearly an hour and focused largely on vaccine distribution.
The president's advisers wouldn't entertain questions on what they will do if Congress doesn't give them the money they need -- insisting it is absolutely critical.

Unlike the predictions given by former President Donald Trump, theirs were not rosy, citing death forecasts that could climb past half a million next month and vaccines still in short supply even as the daily numbers of shots have climbed to 1.6 million.

"It will be months before everyone who wants a vaccine will be able to get one," said Andy Slavitt, another Biden adviser. "Any stockpile that may have existed previously, no longer exists."

Linda Thomas-Greenfield, Biden's nominee for ambassador to the United Nations, testified in front of the Senate Foreign Relations Committee during her nomination hearing Wednesday. During the hearing, Thomas-Greenfield said her three key priories, if confirmed, would be leadership rooted in core values, reforms at the UN, and having a close relationship with lawmakers.

"I've learned that effective diplomacy means more than shaking hands and staging photo ops," Thomas-Greenfield said. "It means developing real robust relationships, it means finding common ground and managing points of differentiation, it means doing genuine old-fashioned, people-to-people diplomacy."

Over her 35-year career, Thomas-Greenfield has been posted Switzerland, Pakistan, Nigeria, Jamaica and elsewhere. Thomas-Greenfield grew up in segregated Baker, Louisiana. If confirmed, she will be only the second Black woman to ever hold the post.

"When we exert our influence in accordance to our values, the United Nations can be an indispensable institution for advancing peace, security and our collective well-being. If instead we walk away from the table and allow others to fill the void the global community suffers, and so do American interest," Thomas-Greenfield said.

New Secretary of State Antony Blinken and his wife, Evan Ryan, participated in a ceremonial swearing-in with Vice President Kamala Harris on Wednesday.

Although daily guidance said the ceremony would take place at the White House, it happened next door, inside the ornate office of the vice president at the Eisenhower Executive Office Building. They stood in front of two American flags and two white State Department flags for the ceremony.

Blinken was confirmed by the Senate in a vote of 78-22 on Tuesday and officially sworn in by a senior career ambassador, Carol Perez, who is currently serving as acting under secretary for management.

Blinken has advised Biden on foreign policy for almost two decades. Previously, he served as deputy secretary of state in the Obama administration, and when serving as national security adviser to Biden, he was present in the Situation Room during the Osama bin Laden raid. Blinken was also a top staffer on the Senate Foreign Relations Committee when then-senator Biden was its chair.

-ABC News' Conor Finnegan