From his mountain perch at the Davos conference on Tuesday, US President Donald Trump saw only a perfect world.

Back in Washington, the Senate was about to enter the heart of the impeachment trial threatening his presidency.

In the Swiss Alps, campaigners warned that climate change threatened the future of the planet itself.

But for the 45th US president, life was as sunny as the blazing white ski slopes flanking the mountains outside the conference centre.

US President Donald Trump
US President Donald Trump dismissed the impeachment and global warming threats alike. Photo: AFP / Fabrice COFFRINI

Worried by impeachment?

That is "just a hoax", he told reporters.

"It's the witch hunt that's been going on for years and frankly it's disgraceful," he said.

Worried by global warming? Trump scoffed again.

"We must reject the perennial prophets of doom and their predictions of the apocalypse," he told a room of the elite business and political types who attend the Davos forum every year.

US President Donald Trump at Davos
SOUNDBITEUS President Donald Trump lashes out at the "perennial prophets of doom" who warn that the world is in the throes of a major environmental crisis, as he addresses an audience in Davos including Swedish teenage campaigner Greta Thunberg. Photo: WORLD ECONOMIC FORUM /

That organisers picked climate change as one of the session's main themes and that teenage campaigner Greta Thunberg was in the crowd did not faze Trump.

"Fear and doubt is not a good thought process," he said. "This is a time for tremendous hope and joy and optimism and action."

As the top billing of the Davos show, Trump bathed in attention from CEOs and politicians all day long. The head of world soccer, FIFA chief Gianni Infantino, even gave him a football and admiringly compared the 73-year-old to a top athlete.

He is "made of the same sort of fibre", Infantino said.

US President Donald Trump at Davos
President Donald Trump flew high above the Alps -- and his political troubles -- with the trip to Davos. Photo: AFP / JIM WATSON

In Washington, fear and loathing, not flattery, were more the order of the day.

Trump's Republican party is all but certain to secure his acquittal on charges of abusing his power and obstructing Congress.

But even before senators kicked off the full-fledged part of the trial, the air was thick with Democratic accusations of cover-ups and Republican complaints about presidential harassment.

Even if Trump is acquitted, the turmoil will have unpredictable effects on an already rancorous reelection campaign. Trump will also have the stain of impeachment on his record.

But whether the subject is impeachment or the climate change that scientists say imperils humanity, Trump seemed determined to see the world through his Trump-tinted glasses.

"America is thriving, America is flourishing, and yes, America is winning again like never before," he said in what sounded more like a stump speech -- minus the swearing, the insults and eccentric rants about poor-quality toilet flushing and other tidbits that delight his supporters.

The applause in Davos was polite but notably quieter than the accolades Trump expects at home.

"I have never been to a session where the applause was so weak for a major public figure," said Noble prize-winning economist Joseph Stiglitz, a frequent Trump critic who was in the room.

"It was clear that they didn't want to boo. That would have been out of tune with the spirit of Davos, but it was clear that he was out of tune with the spirit of Davos."

Trump didn't seem to notice.

"I thought it was very well-received," he told reporters after his speech.

"We're doing very well."

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