A healthy environment is a necessary condition of a stable economy.
Boris Johnson's government must invest in a new "sustainable industrial revolution" to deliver the recovery of nature and the climate, the chairs of two of its agencies have urged.
The Environment Agency's Emma Howard Boyd and Natural England chairman Tony Juniper have called on new prime minister to make environmental issues a top priority.
And they have warned that where once environmental harm was seen as "the price of progress", it is now apparent that a failure to reverse damage to nature, water quality, wildlife losses and climate change will halt progress.
"A healthy environment is a necessary condition of a stable economy," they say in a comment piece published on the Green Alliance website.
Their call comes as parts of the UK battle floods in the wake of a record-breaking heatwave, both extreme weather events which are becoming more likely in the face of climate change.
They warn that there is a pressing need to take action to avoid the biggest global-scale loss of species in more than 60 million years, in what has been described as the sixth mass extinction.
Ms Howard Boyd and Mr Juniper welcomed moves by Mr Johnson to back the new net zero emissions target to tackle climate change, which his predecessor Theresa May set into law before she left office.
But they warned "it is not, however, enough to say 'we will leave the environment in a better state', we need to also invest in delivery".
They called for the government to use the forthcoming spending review to invest in environmental recovery, which they argue would provide opportunities to deliver new clean tech and sustainable agriculture.
"We are convinced that now is the time to find the resources needed for the recovery of natural systems that sustain our society and economy," the agency leaders said.
"A healthy environment is a necessary condition of a stable economy, making the recovery of the environment a sound economic investment.
"It would create huge opportunities to develop clean technologies and new forms of sustainable agriculture. It would also bolster the City of London's leadership in green finance.
"This country was the cradle of the Industrial Revolution and, at this critical juncture in the world's future, now is the time to act and enable the UK to lead once again in a new Sustainable Industrial Revolution.
"If we invest in the recovery of nature and climate we know that it will increase long-term stability for our health, security and prosperity.
"This is the new reality and the present imperative. It is not, as some would see it, an optional 'green' choice that we can only afford in the good times."
Measures to help the environment have public backing, and people are "rightly expecting action", they added.
The Environment Agency and Natural England are public bodies with responsibility for areas including waste, pollution, water quality, flooding, wildlife and landscapes.
Emily Beament is the PA environment correspondent.