From burials in pyramids to scattering ashes and even plastination, there has been no shortage of ideas about how to deal with human corpses.

But with graveyards and crematoria almost full in Britain, the conundrum of what to do with the dead has resurfaced with new urgency. Now a leading public health expert has suggested the sides of motorways, cycle paths and even brownfield or former industrial sites could be transformed to house the dead.

“We need to challenge local authorities and county councils and say as part of their greening strategy – which we must do as part of [mitigating] global warming – let’s put the burial situation into the thinking,” said John Ashton, former president of the Faculty of Public Health.

The upshot, he said, would be the creation of new woodlands and green spaces that would aid greening, help the climate, improve access to the countryside and tackle the graveyard crisis in one stroke.

There are many takes on green burials, but generally they involve burial in a shroud or biodegradable coffin, with no embalming, while trees are often planted as part of the process.

“You have got 500,000 to 600,000 deaths a year in England and Wales so if everybody who died had a green burial – I am not saying that is going to happen – but if everybody did we could be planting half a million trees a year,” Aston said, adding that this would far outstrip Michael Gove’s recently announced plans to plant 130,000 trees in towns and cities to help tackle pollution and global heating.

It is not the only solution that has been mooted: some burial sites have followed the lead of other countries in reusing graves, but others say this will only delay the crisis.

While cremation might seem like an obvious solution, experts say it too has problems as many choose to bury urns, while the process contributes to air pollution and requires significant quantities of fuel. What’s more, some religions and cultures do not permit cremation.

“About 70% of people are cremated, but I think that may have peaked,” said Ashton.

A squeeze on space in burial grounds has previously proved problematic. In the 18th century concerns were raised that the foul-smelling air around the over-filled Holy Innocents cemetery in Paris was a human health hazard, but the situation became even more horrific when people living alongside the site discovered putrefying corpses had burst through the walls of their basements. The graveyard was destroyed after outbreaks of disease.

Writing in the Journal of the Royal Society of Medicine, Ashton discusses new developments in disposal of the dead, including the recent move by Washington state to put an ecological option on the table.

“The latest American offering is that of human composting using a process in which corpses are placed in reusable steel vessels together with wood chips, straw and alfalfa after artificial limbs, joints and pacemakers have been removed,” writes Ashton. “This creates the conditions under which it takes about 30 days for the body to decompose into a compost mulch that can be used to plant a tree or grow vegetables.”

While Aston writes that tentative signs of an enthusiastic reception come “not a moment too soon”, given the world’s growing population and urbanisation, he expects the method to remain a niche approach. “I don’t think I would personally want to be composted,” he said.

Nonetheless he believes the moment is ripe for a change in how we handle human corpses that could embrace the green movement, desires for less formal funerals, concerns about the cost of funerals, and worries about pollution.

Julie Dunk, chief executive of the Institute of Cemetery and Crematorium Management, said the institute had long been advocating for the re-use of graves after 75 years to ease the crisis in cemetery space, and welcomed new approaches.

“As in life we have a duty to protect the planet, so we should in death and it is important that new ideas are considered that provide a respectful and appropriate form of disposal without costing the earth, in both senses,” she said.