Earth's resources "are like a pile of money anyone can grab while they all close their eyes, but then it's gone," said Mathis Wackernagel, lead author of the study and a program director at Redefining Progress.

Scientists said humanity's demand for resources had soared during the past 40 years to a level where it would take the planet 1.2 years to regenerate what people remove each year.

The impact by humans on the environment had inched higher since 1961 when public demand was 70 percent of the planet's regenerative capacity, the study showed.

"If we don't live within the budget of nature, sustainability becomes futile," Wackernagel said.

The study, which details the population's impact on the Earth with a quantitative number, measured the "ecological footprint" of human activities such as marine fishing, harvesting timber, building infrastructure and burning fossil fuel that emits carbon dioxide (CO2) into the atmosphere.

Researchers then used government data and various estimates to determine how much land would be required to meet human demand for those actions.

For example, Wackernagel and his team found that in 1999, each person consumed an average of 5.7 acres (2.3 hectares). The global average was significantly lower than industrialized countries such as the United States and United Kingdom where 24 acres (9.6 hectares) and 13.3 acres (5.3 hectares), respectively, were consumed per person.

"ECOLOGICAL BANKRUPTCY"

In order to develop a formula that measured humanity's consumption with the Earth's regenerative capacity, the researchers were forced to reach several assumptions and omit the use of some resources because of insufficient data.

The results, for example, excluded the impact of local freshwater use and the release of solid, liquid or gaseous pollutants other than CO2 into the environment.

Even though the findings revealed that human use of resources was far outstripping Earth's supply, it stopped short of determining how long the process could continue without detrimental consequences.

"Like any responsible business that keeps track of spending and income to protect financial assets, we need ecological accounts to protect our natural assets," Wackernagel said. "And if we don't ... we will prepare for ecological bankruptcy."

Wackernagel said the study's results could be used to gauge the impact of new technologies and how they affect the environment.

The use of an alternative technology, such as one that produces renewable energy or replaces natural biological processes, could allow society to live better without increasing consumption, he said.