The Catholic tradition of abstaining from meat on a Friday dates back to the 9th century - but many have ditched it in recent decades.
The Pope could slash global carbon emissions by urging Catholics to forgo meat on Fridays, a new study claims.
For over a thousand years, many Christians have abstained from meat on Fridays.
In recent decades, various national church authorities have relaxed the millennia-old tradition.
But bringing it back could have major environmental benefits, a University of Cambridge study claims.
“Meat agriculture is one of the major drivers of greenhouse gas emissions,” said Shaun Larcom, Cambridge University Land Economy researcher.
“If the Pope was to reinstate the obligation for meatless Fridays to all Catholics globally, it could be a major source of low-cost emissions reductions.
“Even if only a minority of Catholics choose to comply.”
How much would Catholic meat free Fridays help the climate crisis?
For Christians, the practice of meat free Fridays dates back at least 1100 years.
In the 9th Century, Pope Nicholas I declared that believers should abstain from eating “flesh, blood, or marrow” on Fridays in memory of Christ’s death and crucifixion.
To determine the environmental benefits of the ancient tradition, researchers assessed the impact of a case study in the UK.
In 2011, The Catholic bishops of England and Wales called on congregations to return to meat-free Fridays.
Just a quarter of the 5 million Catholics in England and Wales changed their dietary habits – yet this still saved over 55,000 tonnes of carbon a year, the researchers found.
This is equivalent to 82,000 fewer return flights from London to New York over the course of a year.
Around the world, 1.3 billion people identify as Catholic.
A papal decree would reinstate the obligation to follow meatless Fridays across the entire global church, saving millions of tonnes of greenhouse gases.
National bishop conferences could also reintroduce the requirement.
“For instance, even if only the United States Catholic bishops were to follow suit, the benefits would likely be 20 times larger than in the UK,” the study’s authors write.
Traditionally, believers substitute meat for fish on Fridays but the study does not assess the impact a mass switch could have on overfishing.
What is the Catholic Church doing about Climate change?
Pope Francis has called for “radical” responses to climate change.
In a 2015 papal letter entitled ‘Laudato Si’, the Pope described the fight against climate change as a “moral imperative.”
“Never have we so hurt and mistreated our common home as we have in the last two hundred years,” he said.
“Those who will have to suffer the consequences . . . will not forget this failure of conscience and responsibility.”
In July, Pope Francis called on young people to eat less meat to help the planet.