Humans are gobbling up almost a quarter of nature's resources, according to a new study by a team of Austrian researchers from Klagenfurt University, Vienna.
Using UN Food and Agriculture Organisation data on agricultural land use in 161 countries, Helmut Haberl and his colleagues found that increasing consumption of resources by humans was leading to a gradual depletion of species and habitats.
By comparing carbon consumption through human activity with the amount of carbon consumed overall, the team found that humans were using up to 15.6 trillion kilograms of carbon annually.
Almost half was soaked up by growing crops; Seven per cent went up in smoke as fires lit by humans, and the rest was used up in a variety of other ways related to industrialisation, such as transport, the study revealed.
According to the study, the Earth can just about cope if the future needs are met by producing food more efficiently, but things could get worse, "if plants like palm oil and rapeseed are grown for biofuels to ease reliance on fossil fuels".
"We are asking for trouble, if we expand production of biofuels, as the only fertile land available is tropical rainforests," said Haberl.
"If we want full-scale replacement of fossil fuels by biofuels, this would have dramatic implications for ecosystems," he said.
According to some projections, there will be four to fivefold increase in biofuel production, which would mean completely clearing what little remains of the Brazilian and Argentinean rainforests.
Not only would this wipe out thousands of species, but would also have a devastating effect on the climate.
"Unlike farmland, forests help to seed rainfall because they have high evaporation rates. The less evaporation there is, the less rainfall there is and the whole system dries up," said Haberl.
The findings appear in the Proceedings of the National Academy of Sciences (PNAS), reports New Scientist.