UN Secretary General Antonio Guterres has urged governments to use their economic responses to the coronavirus pandemic to tackle the "even deeper emergency" of climate change, in a message for the 50th anniversary of Earth Day.
Earth Day is a global demonstration of support for environmental protection, which this year is taking place through online events.
With global battle lines emerging between investors backing "green stimulus" measures and industry lobbyists aiming to weaken climate regulations, Mr Guterres cautioned governments against bailing out heavily polluting industries.
So far, massive economic stimulus packages launched by the United States, China and European governments have focused mainly on staunching the damage to existing industries and staving off the threat of a global depression.
Nevertheless, in the past week, ministers from Germany, France and other EU members have signalled their support for subsequent interventions to align with climate goals, a theme taken up by climate campaign groups around the world.
Mr Guterres, who has made climate change his signature issue since he took over as UN Secretary-General in January 2017, said governments should use their fiscal firepower to drive a shift from "the grey to green" economy.
He said: "Biodiversity is in steep decline. Climate disruption is approaching a point of no return.
"We must act decisively to protect our planet from both the coronavirus and existential threat of of climate disruption."
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Mr Guterres has called for the huge amounts of money that will be spent on recovery to deliver new jobs and businesses through a clean, green transition.
He added that, where taxpayers' money is spent rescuing businesses, it should be tied to achieving green jobs and sustainable growth and should flow to sustainable sectors, suggesting he does not want countries to bail out the struggling oil industry.
"Public funds should be used to invest in the future, not the past, and flow to sustainable sectors and projects that help the environment and the climate."
Fuel subsidies must end and polluters must start paying for their pollution, he warned, adding the financial system and all areas of public policy making and infrastructure must factor in climate risks and opportunities.
A report from the World Meteorological Organisation released to mark the 50th anniversary of the annual Earth Day event, confirms the past five years have been the hottest on record globally.
Additional reporting: PA