Activist Greta Thunberg has launched a scathing attack on Donald Trump’s stance over the climate crisis, claiming his “inaction is fuelling the flames”.

Speaking to world leaders and industrialists on the same day the president bragged about the US economy and attacked climate activists as “perennial prophets of doom”, the 17-year-old Swede said Mr Trump’s vow to plant more trees was sorely inadequate to address the situation.

“’Unlike you, my generation will not give up without a fight. Our house is still on fire,” Ms Thunberg said at the World Economic Forum at Davos, Switzerland, echoing the words she used a year ago at the same event.

“Your inaction is fuelling the flames.”

Mr Trump attacked Ms Thunberg and other activists who have repeatedly urged world leaders to address the crisis they say is rapidly reaching the point where it will soon become too late to act. In a subsequent newspaper interview, Mr Trump repeated his assertion that the teenager was “angry”.

Climate change: Decade's defining issue in pictures Show all 20 1 /20 Climate change: Decade's defining issue in pictures Climate change: Decade's defining issue in pictures California In this decade, humans have become ever more aware of climate change. Calls for leaders to act echo around the globe as the signs of a changing climate become ever more difficult to ignore Getty Climate change: Decade's defining issue in pictures Athens, Greece Fierce wildfires have flared up in numerous countries. The damage being caused is unprecedented: 103 people were killed in wildfires last year in California, one of the places best prepared, best equipped to fight such blazes in the world AFP/Getty Climate change: Decade's defining issue in pictures Redding, California Entire towns have been razed. The towns of Redding and Paradise in California were all but eliminated in the 2018 season AP Climate change: Decade's defining issue in pictures Athens, Greece While wildfires in Greece (pictured), Australia, Indonesia and many other countries have wrought chaos to infrastructure, economies and cost lives AFP/Getty Climate change: Decade's defining issue in pictures Carlisle, England In Britain, flooding has become commonplace. Extreme downpours in Carlisle in the winter of 2015 saw the previous record flood level being eclipsed by two feet AFP/Getty Climate change: Decade's defining issue in pictures Hebden Bridge, England Hebden Bridge in West Yorkshire has flooded repeatedly in the past decade, with the worst coming on Christmas Day 2015. Toby Smith of Climate Visuals, an organisation focused on improving how climate change is depicted in the media, says: "Extreme weather and flooding, has and will become more frequent due to climate change. An increase in the severity and distribution of press images, reports and media coverage across the nation has localised the issue. It has raised our emotions, perception and personalised the effects and hazards of climate change." Getty Climate change: Decade's defining issue in pictures Somerset, England Out west in Somerset, floods in 2013 led to entire villages being cut off and isolated for weeks Getty Climate change: Decade's defining issue in pictures Dumfries, Scotland "In summer 2012, intense rain flooded over 8000 properties. In 2013, storms and coastal surges combined catastrophically with elevated sea levels whilst December 2015, was the wettest month ever recorded. Major flooding events continued through the decade with the UK government declaring flooding as one of the nation's major threats in 2017," says Mr Smith of Climate Visuals Getty Climate change: Decade's defining issue in pictures London, England Weather has been more extreme in Britain in recent years. The 'Beast from the East' which arrived in February 2018 brought extraordinarily cold temperatures and high snowfall. Central London (pictured), where the city bustle tends to mean that snow doesn't even settle, was covered in inches of snow for day PA Climate change: Decade's defining issue in pictures London, England Months after the cold snap, a heatwave struck Britain, rendering the normally plush green of England's parks in Summer a parched brown for weeks AFP/Getty Climate change: Decade's defining issue in pictures New South Wales, Australia Worsening droughts in many countries have been disastrous for crop yields and have threatened livestock. In Australia, where a brutal drought persisted for months last year, farmers have suffered from mental health problems because of the threat to their livelihood Reuters Climate change: Decade's defining issue in pictures Tonle Sap, Cambodia Even dedicated climate skeptic Jeremy Clarkson has come to recognise the threat of climate change after visiting the Tonle Sap lake system in Cambodia. Over a million people rely on the water of Tonle Sap for work and sustinence but, as Mr Clarkson witnessed, a drought has severley depleted the water level Carlo Frem/Amazon Climate change: Decade's defining issue in pictures Addis Ababa, Ethiopia In reaction to these harbingers of climate obliteration, some humans have taken measures to counter the impending disaster. Ethiopia recently planted a reported 350 million trees in a single day AFP/Getty Climate change: Decade's defining issue in pictures Morocco Morocco has undertaken the most ambitious solar power scheme in the world, recently completing a solar plant the size of San Francisco AFP/Getty Climate change: Decade's defining issue in pictures London, England Electric cars are taking off as a viable alternative to fossil fuel burning vehicles and major cities across the world are adding charging points to accomodate AFP/Getty Climate change: Decade's defining issue in pictures Purmerend, The Netherlands Cities around the world are embracing cycling too, as a clean (and healthy) mode of transport. The Netherlands continues to lead the way with bikes far outnumbering people Jeroen Much/Andras Schuh Climate change: Decade's defining issue in pictures Xiamen, China Cycling infrastructure is taking over cities the world over, in the hope of reducing society's dependency on polluting vehicles Ma Weiwei Climate change: Decade's defining issue in pictures Chennai, India Despite positive steps being taken, humans continue to have a wildly adverse effect on the climate. There have been numerous major oil spills this decade, the most notable being the BP oil spill in the Gulf of Mexico in 2010 AFP/Getty Climate change: Decade's defining issue in pictures Amazon rainforest, Brazil More recently, large swathes of the Amazon rainforest were set alight by people to clear land for agriculture AFP/Getty Climate change: Decade's defining issue in pictures California This decade may have seen horrors but it has led to an understanding that the next decade must see change if human life is to continue Getty

“This is not a time for pessimism. This is a time for optimism,” said Mr Trump. “Fear and doubt is not a good thought process because this is a time for tremendous hope and joy and optimism and action.”

He added: “To embrace the possibilities of tomorrow, we must reject the perennial prophets of doom and their predictions of the apocalypse.”

She added: “Planting trees is good, of course, but it’s nowhere near enough. It cannot replace mitigation.”

The Swede said she was referring to “empty words and promises” by world leaders.

She added: “You say children shouldn’t worry... don’t be so pessimistic and then, nothing, silence.”

Thunberg leaves after Trump finishes his speech in Davos (Reuters)

Earlier, Mr Trump, 73, who swiftly moved to withdraw the US from the Paris climate accord when he was elected president, and who has pushed policies critics say have further weakened environmental standards, said Washington was signing an agreement to plant more trees.

Ms Thunberg responded without naming the US president, although it was patently clear who she was referring to.

“We need to start listening to the science, and treat this crisis with the importance it deserves,” she said. “Without treating it as a real crisis we cannot solve it.”

Greta Thunberg addresses climate march in Switzerland

Earlier, Ms Thunberg called on world leaders to listen to young activists who have followed her to Davos this year.

“I’m not a person that can complain about not being heard,” she said. “The science and voice of young people is not the centre of the conversation, but it needs to be.”

The world’s top scientists have repeatedly warned that immediate action is required to address the climate crisis.

With the world experiencing record high temperatures and an increase in the incidence of “extreme” events such as Australia’s wildfires, scientists have called on nations to act to try to limit the rise in global temperature of 1.5C.

The Swedish activist attends a session at the 50th World Economic Forum yesterday (Reuters)

“We cannot accept insufficient action anymore,” professor Gail Whiteman, director of the Pentland Centre for Sustainability in Business at Lancaster University, said in a statement. “If we’re united behind the science then every decision, every investment, every behaviour should be based on what is taking us in the right direction.”

Meanwhile, the UN High Commissioner for Refugees said the world needed to prepare for a surge in refugees, with potentially millions of people being driven from their homes by the impact of climate change.

“We must be prepared for a large surge of people moving against their will,” said Filippo Grandi. “I wouldn’t venture to talk about specific numbers, it’s too speculative, but certainly we’re talking about millions here.”

Michael Mann, a climate expert and Professor of Earth Sciences at Penn State University, praised Ms Thunberg’s comments.

“Planting trees is a veritable drop in the bucket. We need to solve this problem at its source – fossil fuels,” he told The Independent.

“Trump here is doing the bidding of the fossil fuel interests that run his energy and environmental policy, engaging in an effort to deflect attention away from the need to rein in the fossil fuel industry and transition away from the burning of fossil fuels. Good on Greta for calling out his villainy.”