(AFP) - World powers must pull together and retool their economies for a green future or humanity is "doomed", UN chief Antonio Guterres has warned, telling AFP that failure to control the coronavirus pandemic illustrates the danger of disunity.

Before the virus struck, 2020 was billed as a pivotal year for the plan to dodge the bullet of catastrophic global warming, with high profile summits planned to catch a wave of public alarm over the future of the planet.

The coronavirus crisis may have shunted climate into the sidelines as nations launched unprecedented shutdowns to try to slow its spread, but Guterres said the need for climate action was more urgent than ever.

In a searing assessment of the international response, Guterres said the pandemic should sharpen governments' focus on cutting emissions, urging them to use the crisis as a springboard to launch "transformational" policies aimed at weaning societies off fossil fuels.

"I think the failure that was shown in the capacity to contain the spread of the virus -- by the fact that there was not enough international coordination in the way the virus was fought -- that failure must make countries understand that they need to change course," he told AFP.

"They need to act together in relation to the climate threat that is a much bigger threat than the threat of the pandemic in itself -- it's an existential threat for our planet and for our lives."

The UN chief said "pollution and not people" should be taxed and called for nations to end fossil fuel subsidies, launch massive investments in renewables and commit to "carbon neutrality" -- net zero emissions -- by 2050.

"We need to have a number of transformational measures in relation to energy, in relation to transportation, in relation to agriculture, in relation to industry, in relation to our own way of life, without which we would be doomed," he said.

His comments come as the landmark Paris climate deal goes into effect this year in a bid to cap the rise in temperature to "well below" two degrees Celsius (3.6 Fahrenheit) above pre-industrial levels.

The accord was already on a knife edge before the pandemic, with doubts over commitments from major polluting nations and concerns that it is still far short of what science says is needed to avert disastrous climate change.

US President Donald Trump shocked the world in 2017 when he said the United States -- history's largest emitter -- was withdrawing from the Paris deal. It is due to leave on November 4, just after the country's presidential election.  

The pandemic has further dented hopes that diplomatic pressure could sweep foot-dragging nations into announcing bold climate action plans, as major summits were postponed and nations focused inwards.

Guterres said there was currently no clear sign that a United States government recovery policy would align with Paris goals, but he expressed hope that states, businesses and individuals "will compensate for the lack of political commitment that exists at the present moment".

He said much now rests on the actions of major emitters, China, the US, Europe, Russia, India and Japan, in interviews with AFP and other members of Covering Climate Now, a global collaboration of news outlets committed to increased climate coverage.   

"We have never been as fragile as we are, we never needed as much humility, unity and solidarity as now," he said, blasting "irrational demonstrations of xenophobia" and the rise of nationalism.

"Either we are united, or we will be doomed," he added, ahead of a largely virtual UN General Assembly this month.

- 'Wake up'-

Climate change warnings are no longer predictions of a distant future.

Earth's average surface temperature has gone up by one degree Celsius since the 19th century, enough to increase the intensity of droughts, heat waves and tropical cyclones.

Burning fossil fuels has been by far the main driver of rising temperatures, with concentrations of CO2 in the atmosphere now at their highest levels in around three million years.

The last five years were the five hottest on record, while ice sheets are melting at a rate that tracks scientists' worst-case scenarios, prefiguring devastating sea level rises.

"The expectations that we have in relation to the next five years about storms, about drought and about other dramatic impacts in the living conditions of many people around the world are absolutely terrible," Guterres said, ahead of a multi-agency climate report on Wednesday.

The United Nations says it is still possible to reach a safer goal of a 1.5C cap in temperature rise, but to get there global emissions must fall 7.6 percent annually this decade.

While the shutdowns implemented during the pandemic could reduce global emissions by up to eight percent in 2020, scientists have warned that without systemic change in how the world powers and feeds itself, the drop would be essentially meaningless.

- 'A different world' -

There are also concerns that massive Covid-19 stimulus packages being devised by governments could provide a crutch to polluting industries.   

Guterres has urged Japan, India and China to drop their continued reliance on coal.

China -- the world's biggest polluter -- has invested heavily in renewable energy, but it has also reportedly stepped up coal production.

The UN head said he was hopeful the EU would make good on its green commitments, after it announced its 750-billion-euro ($885 billion) stimulus plan that aims in part to reach carbon neutrality targets.

He said the pandemic had demonstrated society's capacity to adapt to transformation.

"I don't want to go back to a world where biodiversity is being put into question, to a world where fossil fuels receive more subsidies than renewables, or to a world in which we see inequalities making societies with less and less cohesion and creating instability, creating anger, creating frustration," he added.  

"I think we need to have a different world, a different normal and we have an opportunity to do so."

© Agence France-Presse