Prize experts are split over who will get it.

One camp thinks this year's award winner will be a critique of Russian President Vladimir Putin's invasion of Ukraine.

The other believes it will highlight the urgent need to combat global heating.

With a total of 343 top-secret nominations this year, the five members of the Norwegian Nobel Committee could also surprise experts and go with a completely different pick.

Henrik Urdal, director of the Peace Research Institute Oslo (PRIO), said the Belarusian opposition leader Svetlana Tikhanovskaya and jailed Kremlin critic Alexei Navalny deserved to win the prestigious honour together.

"These are both champions of non-violent pro-democracy activities within their own countries," he said.

"And both Navalny and Tikhanovskaya have also been very strong opponents of the war in Ukraine".

Not since World War II has a conflict raged between two countries so close to Oslo, the home of the Peace Prize.

The committee could also make a statement against Putin's war by giving the Nobel to those documenting suspected war crimes in Ukraine, such as the International Criminal Court (ICC) or digital investigative group Bellingcat.

- 'Now or never' -

And what about Ukrainian President Volodymyr Zelensky, the symbolic figure of his country's resistance and one of the favourites to win among bookies?

"The committee would likely be extremely careful about giving the prize to a president at war... even if Ukraine is at the receiving end of this war and hasn't deserved it," said Urdal.

"There will always be atrocities, even on the Ukrainian side."

Thousands of people around the world are eligible to nominate candidates for the prize before the January 31 deadline, including members of parliament and cabinet ministers from all countries, former laureates and some university professors.

The Nobel committee members are also free to submit their own choices during their first meeting, this year held shortly after the start of the Russian invasion of Ukraine on February 24.

Other observers say efforts to fight climate change would be worthy of a Nobel after another year marked by extreme weather events, including Europe's record-breaking heatwave and devastating floods in Pakistan.

United Nations climate experts issued a clear warning in a deeply sombre report in April.

"It's now or never, if we want to limit global warming to 1.5 degrees Celsius," said Jim Skea, co-chair of the working group behind the report.

- No prize? -

"By giving the Peace Prize to climate change, the Nobel committee would have the unique possibility to say that the multiple crises the world is facing must be resolved together," said Oda Andersen Nyborg, head of the Norwegian Peace Council.

Among the names mentioned for a possible climate prize are Swedish campaigner Greta Thunberg and/or her Fridays for Future movement, tireless British naturalist David Attenborough and other activists.

Yet others include United Nations Secretary-General Antonio Guterres, the UN Framework Convention on Climate Change (UNFCC) and Tuvalu Foreign Minister Simon Kofe, whose country's existence is threatened by rising sea levels.

If the committee were to honour work in other fields, human rights activists from China, Afghanistan and Iran could get the nod, as could anti-corruption organisation Transparency International or the International Court of Justice.

According to Sverre Lodgaard, researcher at the Norwegian Institute of International Affairs (NUPI), the committee could also choose to not award the prize at all this year.

The last time it did so was 50 years ago.

"Nobody can claim to have made any great breakthroughs in the field of peace, the conflicts seem never-ending, and treaties seem to be there to be violated," he told AFP.

Last year, the Nobel Peace Prize was awarded to two champions of press freedom -- Maria Ressa of the Philippines, whose news outlet is under threat of being shut down, and Russia's Dmitry Muratov, whose media organisation has had its licence revoked.