US President Donald Trump arrived in Davos on Tuesday for the annual WEF forum, where he was to give a keynote speech just hours before his impeachment trial kicks into high gear in Washington.

Swedish teen activist Greta Thunberg on Tuesday slammed global inaction on climate change in front of the world's top business leaders, as the annual Davos forum faced up to the perils of global warming while bracing for an address from US President Donald Trump.

The starkly opposed visions of US President Donald Trump and Swedish teen activist Greta Thunberg on climate change will clash in Davos on Tuesday as the World Economic Forum tries to face up to the perils of global warming on its 50th meeting.