The annual World Economic Forum kicked off with US president Donald Trump criticising climate activists, in contrast with young activist Greta Thunberg who urged the leaders for climate action. They did not directly mention each other.

In his speech, Trump rejected climate emergency, which is a key topic of this year’s economic forum: “We must reject the perennial prophets of doom and their predictions of the apocalypse”, Trump said, and called the climate activists “heirs of yesterday’s foolish fortune tellers”.

He also called on the EU to “use America’s vast supply” of energy products and stressed that technical innovation, and not restricting economic growth, is the way forward. He then praised the US economy, as well as the US-China relationship, which entered a new, quieter phase with the newly signed Phase One trade deal. “Today I’m proud to declare that the United States is in the midst of an economic boom the likes of which the world has never seen before,” he said.

Hours later, Thunberg said that governments had done nothing to reverse climate change: “Pretty much nothing has been done as global Co2 emissions have not been reduced. And that is of course what we are trying to achieve”, she said, and accused leaders of “cheating and fiddling around with numbers” with talk of cutting emissions to ‘net zero’: “You just leave it because you think it’s too depressing and people will give up, but people will not give up. You are the ones who are giving up”, she said.

She referred to a 2018 UN report that calculated the amount of additional carbon dioxide the atmosphere can absorb before global average temperature increases exceed 1.5 degrees Celsius. Scientists warn the chances of staying below that threshold are decreasing.

Thunberg was joined by three other young activists, who also said politicians and executives are not doing enough.