The UK is responsible for almost 30% more carbon dioxide than it reports, the conservation organisation WWF says.
More species struggle to survive (Image: WWF-Canon/Martin Harvey)
WWF's Living Planet Report 2004 says Britain counts only CO2 emitted by UK industry, power plants and vehicles.
But WWF says most of the UK's food, raw materials and manufactured goods are imported, so the economy is generating CO2 emissions elsewhere on the planet.
Globally, it says, humans are consuming the Earth's resources at a pace that outstrips its capacity to support life.
Short of planets
The Living Planet Report calculates the amount of resources used - which it calls the ecological footprint - by 148 countries.
If everyone on Earth consumed at the level Britons do, it says, we should need almost three planets to support ourselves.
The report says humans currently consume 20% more natural resources than the Earth can produce, and that populations of terrestrial, freshwater and marine species fell on average by 40% between 1970 and 2000.
Dr Claude Martin, director-general of WWF International, said: "We are spending Nature's capital faster than it can regenerate.
"We are running up an ecological debt which we won't be able to pay off unless governments restore the balance between our consumption of natural resources and the Earth's ability to renew them."
Hair shirts not needed
The report says our ecological footprint has increased two and a half times since 1961. It says the average global footprint is 2.2 hectares (5.4 acres) per person, while there are only 1.8 hectares (4.4 acres) of land to provide resources for each of the planet's people.
This is based on dividing the Earth's 11.3bn hectares (28bn acres) of productive land and sea space between its 6.1bn people.
Pollution remains a problem in many countries (Image: WWF/Kjell-Arne Larsson)
WWF says our energy footprint increased by nearly 700% between 1961 and 2001; and an average North American consumes twice as many resources as a European, and seven times as much as the average Asian or African.
Jonathan Loh, one of the authors of the report, said: "Sustainable living and a high quality of life are not incompatible.
"However, we need to stop wasting natural resources and to redress the imbalance in consumption between the developing and industrialised worlds."
The UK's governing Labour party committed itself in its 1997 manifesto to a 20% cut in CO2 by 2010, but emissions have increased since then.
Credibility in balance
WWF-UK accuses the government of misleading people over the amount of CO2 the UK causes.
Andrew Lee, its campaigns director, said: "Unless the UK government acknowledges the wider picture and shows commitment to tackling the causes of climate change... it will fatally undermine Tony Blair's legitimacy to take a global lead on this issue.
"The impact of the UK economy on the global environment cannot be reduced unless that impact is properly measured.
Global fish stocks face unsustainable pressure (Image: WWF-Canon/Jurgen Freund)
"This requires a real system of national accounts, which shows how the way we live now uses resources and produces pollution around the world.
"We are developing such a system, and hope that it will be taken up by government."
The Department for Environment, Food and Rural Affairs (Defra) said: "CO2 emissions increased, relative to the previous year, in 2003.
"They increased by about 1.5% between 2002 and 2003, although they still remain lower than in 2001.
A Defra spokesman told the BBC: "The government isn't misleading the public; the UK's greenhouse gas inventory is compiled according to internationally accepted guidance.
"Emissions associated with production of goods imported should be included within the inventories of the country of production. Emissions associated with transport of goods to the UK by sea and air are estimated and appear in the inventory."