What the initial UN Climate Summit attendance list reveals

The UN Climate Summit set to begin Oct. 31 in Glasgow will bring an unprecedented combination of leaders for such an event (even Pope Francis!), and the likely absence of vital players — notably Chinese President Xi Jinping. 

Why it matters: The speeches and backroom meetings at COP26 between leaders on the summit's first two days will set the tone for the rest of the gathering. These will be moments when countries showcase any new pledges to cut greenhouse gas emissions in order to meet the Paris Agreement's targets.

• Without bold new emissions cuts in the near-term, the UN recently warned, the world is headed for at least 2.7°C (4.9°F) of warming above preindustrial levels by 2100 — well above the Paris temperature targets.

Yes, but: Developments ranging from U.S.-China tensions to the spiraling energy crisis in Europe and Asia, in particular, could diminish the emissions goals and climate finance commitments that are needed to head off the most severe impacts from global warming.

What to watch: Here's a look at what we know about the unofficial RSVP list so far — and how the arrivals and snubs may shape the summit:

President Biden will definitely attend and will tout his emissions goals. But whether he walks in the door with legislation enacted to back up his pledges is anyone's guess right now. The U.S. is the world's leading historical emitter and second-largest current emitter of planet-warming greenhouse gases.

• However, it's looking dicey as to whether any major climate legislation will have passed the Senate and House by then, as part of a Democrats-only measure.
• This would leave Biden with a lot of unfulfilled promises, and could make other leaders more skeptical of America's ability to slash emissions and devote additional funding to helping developing nations adapt to global warming.

Pope Francis will be the first pontiff ever to attend a COP. His 2015 Encyclical on the environment was widely read around the world, and acting to combat climate change is one of his signature issues.

Canada's Prime Minister Justin Trudeau will be there, while French President Emmanuel Macron will be among the European leaders attending.

U.K. Prime Minister Boris Johnson will host the event, and the country's Queen Elizabeth II is also expected.

Between the lines: There are some big names playing it coy so far, and China's Xi tops the list.

• Nor do we know if Indian Prime Minister Narendra Modi will attend, despite multiple visits to his country by Biden's climate envoy, John Kerry, and Modi's recent visit to the White House.
• India is expected to unveil a new goal — but the form it will take is not yet known. It could include new targets for renewable energy usage or emissions reductions, or both, David Waskow, director of the World Resources Institute's International Climate Initiative, told Axios.

Also on the "maybe list": Australian Prime Minister Scott Morrison, who recently visited the White House and committed to taking some sort of additional climate action.

• Regardless, look for a new carbon or net zero target from the Australian government, however, Waskow said. In recent days, Morrison's government has gone in the opposite direction from clean energy by approving new coal mines.

Russian President Vladimir Putin is, as usual, a wild card, as his country is home to vast oil and gas reserves, but on Wednesday he spoke of the need for a "planned transition" to clean energy. There's some speculation that Russia will unveil a long-term carbon reduction strategy as well, but it may be as far out as 2060.

Brazil's President Jair Bolsonaro may be another no-show, as his country suffers through a devastating drought amid spikes in deforestation related to government policies, and he faces corruption probes.

Of note: Heads of state from countries most vulnerable to climate impacts, such as small island nations, will bring a moral perspective, since if the world doesn't act quickly to sharply curtail emissions, their homes could sink beneath rising seas.

• Look for the leaders of Palau and the Marshall Islands to play outsized roles.
• Coronavirus-related travel restrictions are likely to affect the list of leaders and especially the size of delegations, with many from developing nations who lack access to vaccines forced to navigate a web of bureaucracy to make it into the negotiating halls.

The bottom line: This summit is being billed as a make-or-break moment for the planet and everyone living on it. Judging by the list of leaders planning to go, it's not clear that it's being treated that way by those who need to be part of the solution.