Swedish environmental activist Greta Thunberg attends an interview with the Associated Press in New York. File picture: Eduardo Munoz Alvarez/AP

Geneva - Some of the world's most powerful leaders, including US President Donald Trump and German Chancellor Angela Merkel, are set to trek to the Swiss mountains next week to mark the 50th anniversary of the summit in the village of Davos.

As global power is no longer measured in troops and economic prowess but also in social media influence, it is 17-year-old Greta Thunberg who sets the tone for the meeting that highlights the challenges of the year and the decade ahead.

In an open letter published ahead of the World Economic Forum in Davos, Thunberg and a group of young climate campaigners demanded an immediate global stop to subsidies and investments related to fossil fuels.

"In an emergency you step out of your comfort zone and make decisions that may not be very comfortable or pleasant," they wrote in Britain's Guardian newspaper.

The World Economic Forum's 81-year-old founder Klaus Schwab, who organizes the event for thousands of politicians and businessmen in Davos each year, has not only invited her for the second year in a row but has also adopted some of her language.

He reminded reporters on Tuesday the world is facing a "state of emergency."

Klaus Schwab, Founder and Executive Chairman of the World Economic Forum, WEF, gestures during a press conference, in Cologny near Geneva, Switzerland. Picture: Valentin Flauraud/Keystone via AP

"We do not want to reach the tipping point on climate change," he told a press conference. "We do not want that the next generations inherit a world which becomes ever more hostile and ever less habitable - just think of the wildfires in Australia."

The summit that runs from Tuesday to Friday next week would also focus on various other pressing problems, according to the organizers, including slowing global economic growth, trade wars, geopolitical tensions in East Asia and Middle Eastern hot spots.

While the list of attendees includes country and government leaders from Jordan, the Palestinian Authority, Iraq, Afghanistan and Pakistan, there is one glaring absence: Iran's Foreign Minister Mohamad Javad Zarif.

Zarif's cancellation means that the Islamic regional power that is involved in an escalating nuclear spat with world powers and in various Middle Eastern crises will not be represented in Davos.

The World Economic Forum prides itself of having served as a venue for fostering diplomacy in the past 50 years, including a 1987 speech by West German Foreign Minister Hans-Dietrich Genscher that has been cited as a watershed moment for the end of the Cold War.

A year later, meetings between Turkish and Greek leaders in Davos helped to prevent a war between the Mediterranean rivals.

In addition, the World Economic Forum has helped to spawn several international initiatives, such as the G20 group of major developed and developing economies. The Global Alliance for Vaccines and Immunization, and the Global Fund to Fight Aids, Tuberculosis and Malaria were also launched in Davos.

Despite these achievements, Davos has also been criticized of being a place where great new ideas are pondered by the world's elites, with few concrete results.

However, Schwab is working hard to counter nay-sayers.

The programme of this year's meeting was organized around the concept of "stakeholder capitalism." Schwab wants to promote this idea as a way of getting companies to act responsibly towards society and the environment, rather than only to shareholders.

In addition, Schwab announced that a global initiative would be launched next week to train 1 billion people over the next decade so that they can cope with the changes that digitalization brings to workplaces; as well a new plan to plant 1 trillion trees by 2030.

dpa