President-elect Joe Biden faces a tough balancing act as he calls for more global action on climate change while also reassuring the world that America is on board for the long haul.

Driving the news: World leaders will convene virtually on Saturday to mark the fifth anniversary of the Paris Climate Agreement, which was agreed to by nearly all countries on Dec. 12, 2015.

How it works: The Paris deal calls on nations to submit plans every five years to cut their greenhouse gas emissions, limiting the global temperature rise to below two degrees Celsius compared to pre-industrial levels by the end of this century.

• Biden has said he will rejoin the deal on the first day of his presidency, which, according to the deal’s rules, will become official a month later.
• Although Biden may still recognize the anniversary, he isn't going to be involved in the Dec. 12 summit. "President-elect Biden and his team respect the principle that there is one president at a time," said Ned Price, a spokesman for the transition team.
• John Kerry, who as Barack Obama’s secretary of state signed the Paris deal in 2015, is returning to government as Biden’s special envoy for climate change. It’s a new role that will position Kerry as America’s central diplomat in this area.

Where it stands: A lot has changed on the climate front over the five years since the deal was inked. Most notably, President Trump announced in 2017 he was withdrawing America from the deal.

• That actually marked the second time America retreated from a global climate deal after a change from a Democratic president to a Republican one. (The other was the Kyoto Protocol in the early 2000s, which George W. Bush left after Bill Clinton joined it.)
• “World leaders welcome the U.S. coming back into Paris and the international stage,” said Alden Meyer, a longtime strategist on global climate policy. “The concern will be, how can we be sure that whatever this administration does has some staying power beyond changes in administration?"

Much of the world has moved forward, despite Trump’s retreat.

• Europe has been pushing aggressive climate policy over the last five years, and recent comments suggest it may not let America lead like it has in the past.
• “Europe will be at the forefront of brokering ambitious commitments,” said European Commission President Ursula von der Leyen in comments last month. “The U.S. is also well placed to support us.”
• This fall, China, South Korea and Japan all announced aggressive goals to drastically cut emissions over the next three decades.
• These announcements, critical given that they’re coming from energy-hungry Asia, were made in anticipation of a Biden presidency, said one former U.S. diplomat.

The intrigue: The official U.S. commitment to the deal is not expected immediately in the new administration, according to Pershing and other experts familiar with the process.

• That's because it takes time — and technical experts — to determine what policies are possible and how much emissions reduction would result.
• "There will likely be an announcement of intent and then delivery of the plan within the first year," Pershing said.

By the numbers: Given the limits of Biden’s domestic political agenda, the pledge is likely to lean more heavily than ever before on non-federal action, which there's been a lot of over the last four years.

• Action by states, cities and private business could cut U.S. emissions up to 37% by 2030 compared to 2005 levels, according to a 2019 report by a consortium of environmental groups and former state leaders.
• That percentage could rise to nearly 50% if the federal government reengaged, the report said.
• To be on a steady path to achieve Biden’s 2050 goal of a zero-carbon economy, he would need to achieve a cut of 43% by 2030, according to analysis done by research firm Rhodium Group. That would be a 2.7-3.3% reduction per year.

Reality check: U.S. emissions have never dropped by so much so consistently. They’re forecast to drop a record 11% this year, purely because the pandemic choked economic activity — not a desirable way to cut emissions.

What we’re watching: The recent wave of 2050 and 2060 targets has put the Paris goal “within striking distance,” according to a new report by the Climate Action Tracker, a consortium of climate research groups.

• It calculated that global warming by 2100 could be as low as 2.1 degrees Celsius as a result of these pledges.
• But, but, but: Those pledges aren’t officially part of the Paris deal. In fact, no large emitting nation has submitted any substantially updated commitments to the agreement since 2015.

The bottom line, per Pershing: “There is not enough underpinning how countries need to implement these goals.”