Bookmakers seem confident that Swedish teen climate activist Greta Thunberg is a shoo-in for the Nobel Peace Prize to be announced this week, but some experts are more cautious.

The 16-year-old has already received Amnesty International's top honour and the Right Livelihood Award, sometimes dubbed the "alternative Nobel", and online betting sites like Ladbrokes now put her as favourite to win what is perhaps the world's most prestigious prize.

Thunberg made global headlines in late September when she lambasted world leaders at the UN climate summit in New York.

But is her impassioned wake-up call enough to earn her the Nobel Peace Prize?

"Extremely unlikely," Henrik Urdal, director of the Peace Research Institute in Oslo (Prio), told AFP, citing two reasons for his scepticism.

He argued that while some say climate change might aggravate conflicts in his view there is still no consensus on whether it is actually the cause of armed conflict. He also said her tender age could make the prize more of a burden than a reward.

"The only way I could see that happen is that she would be part of a shared prize like Malala," Urdal said, referring to Pakistani activist Malala Yousafzai, who shared the 2014 prize - at age 17 -with Indian children's rights activist Kailash Satyarthi.

The 2019 laureate will be revealed on Friday.