By Mark Kinver
BBC News science and nature reporter
The UK is about to run out of its own natural resources and become dependent on supplies from abroad, a report says.
Consumer societies: Good for business or bad for the planet?
A study by the New Economics Foundation (Nef) and the Open University says 16 April is the day when the nation goes into "ecological debt" this year.
It warns if annual global consumption levels matched the UK's, it would take 3.1 Earths to meet the demand.
But bio-geography professor Philip Stott criticised the "doomsday report", arguing it would hit poorer nations.
"What we tend to have - not just with this report but alternative reports on the other side - are two theological positions," said Prof Stott, of London University.
"This one is the kind of Doomsday report - on the other hand the total free-traders are far too optimistic."
He went on: "If we did follow this report for example the damage to the Third World would be very great indeed because of course trade is the main dynamo of growth."
In 1961, the symbolic "ecological debt day" was 9 July; in 1981, it had shifted forward two months to 14 May.
The authors of the UK Interdependence Report hope to highlight the need to curb rising consumption levels.
'Eyes bigger than planet'
Nef policy director Andrew Simms says this year's debt day shows that the UK's growing demand for goods and services is having an impact on the rest of the world.
"On one level, there is absolutely nothing wrong with importing goods and services, but our eyes are bigger than the planet.
UK'S GROWING ECO-FOOTPRINT
In 1961, the Earth could have supported everyone having a UK lifestyle
It would take 3.1 planets to support the current UK lifestyle
"The problem is that we want to have our planet and eat it and not think about the consequences," Mr Simms said.
The findings are based on the concept of "ecological footprints", a system of measuring how much land and water a human population needs to produce the resources it consumes and absorb the resulting waste.
The report, produced by Nef and the Open University's geography department, uses a number of examples that it says illustrate how resources are being wasted, including:
- In 2004, the UK exported 1,500 tonnes of fresh potatoes to Germany, and imported 1,500 tonnes of the same product from the same country
- Imported 465 tonnes of gingerbread, but exported 460 tonnes of the same produce
- Sent 10,200 tonnes of milk and cream to France, yet imported 9,900 tonnes of the dairy goods from France
The authors say this shows how current trade systems are inefficient at a time when there is concern over energy supplies and greenhouse gas emissions.
"If you do not have the right signals within the economy to tell you when you are doing something very environmentally wasteful, then you cannot expect it to stop," says Mr Simms, the report's lead author.
"Lifestyles in Britain are becoming increasingly unsustainable and are placing an ever larger burden on the global environmental system."
The UK's food self-sufficiency has been falling steadily for more than a decade, and indigenous food production is now said to be at its lowest level for half a century.
In 2004, the UK lost its energy independent status when it became a net importer of gas following lower returns from the North Sea fields.
At a global level, the world is also living beyond ecosystems' ability to supply the resources and absorb the demands being placed upon them.
This year's ecological debt day for the world is 23 October.
In the future, it is expected to be even earlier as emerging economies, such as China and India, demand more resources to meet changing lifestyles.
"The earlier it creeps in the year, the more you are permanently running down the Earth's environmental capital.
"The problem is that we are not clever enough to know at what point we will see a crash within eco-systems," Mr Simms told the BBC News website.
"While you are not living within the planet's limits and are eroding ecosystems, and the earlier the ecological day falls in the year, the greater the risk of a system crash."
Mr Simms said developed nations had a responsibility to share their experience and knowledge with developing nations in order to limit the impact on the environment.
However, he added, despite the sharp rise in economic growth in the emerging economies, their consumption levels were still far behind developed nations.
Give and take
Steve Bettison, from the free-market think tank, Adam Smith Institute, described the report as "an interesting concept" but questioned its findings on market inefficiencies.
"The only inefficiencies in the market place are those that relate to government intervention and that do not allow for free trade to occur, such as tariffs on agricultural products, or protectionist measures."
Potato exports to Germany equal what Germany sends to the UK
Mr Bettison said market forces were the best way to control consumption of the world's finite resources: "The usual 'supply and demand' economics will govern where these resources are used.
"This would also drive human ingenuity as people strive to develop new ideas to take up where previous resource supplies have waned," he told the BBC News website.
"It would be interesting to see how the rest of the world is dependent on the services and resources that we have developed over time.
"Whilst we take, we also give - something that seems to have been forgotten."
Andrew Simms said the report was not calling for the UK's borders to be closed because there were many benefits, both economic and cultural, to be gained from closer ties with other nations.
The report builds on previous studies that have used "ecological footprint" measurements, such as the WWF's "one planet living" campaign.
It also echoes last year's Millennium Ecosystem Assessment, the most comprehensive survey ever into the state of the planet. It concluded that human activities threatened the Earth's ability to sustain future generations.
Nef and the Open University hope the "ecological debt day" will be used as an annual yardstick to measure the health of the planet.