Human activity changing the Earth

More than 40 per cent of the Earth's surface has been changed utterly by human activity and the degradation continues apace, …

More than 40 per cent of the Earth's surface has been changed utterly by human activity and the degradation continues apace, according to a new analysis.

Land continues to fall under the plough or get covered in urban concrete. Fish stocks are in decline, fresh water resources are drying up, agricultural lands are being poisoned.

A chilling collection of facts, figures and maps has catalogued the depredations of humans. It was released yesterday at the American Association for the Advancement of Science's (AAAS) annual meeting, now under way in San Francisco.

The AAAS Atlas of Population and Environment shows, in some cases for the first time, how the Earth has been altered by human activity. "It is a huge percentage of the Earth's surface and most people don't get a view of this," said Mr Lars Bromley of the association's programme on ecology and human needs.

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The atlas is actually an accumulation of existing data, culled from a variety of sources, including satellites flown by the US space agency NASA, the US Geological Survey, the World Resources Institute and the United Nations.

"We have become a major force of evolution, not just for the new species we breed and genetically engineer but for the thousands of species whose habitats we modify," the atlas says.

Humans represent one of the most successful species in the history of life. "But our success is showing signs of overreaching itself, of threatening the key resources on which we depend."

Our impact on the Earth has reached "a truly massive scale. In many fields our ecological footprint outweighs the impact of all other living species," says the atlas.

A NASA satellite, the Advanced Very High Resolution Radiometer, used radar to map the entire plant's surface, analysing land use. It showed 24 per cent was either under concrete or under the plough.

If land use is broadened to include pasture and forestry, the figure rises to about 40 per cent.

On fish stocks, the atlas says that while we use only about 8 per cent of the marine resource, two-thirds of fisheries have been fished to their limits or beyond.

Humans have regulated the flow of about two-thirds of all the Earth's rivers, creating artificial lakes and changing the ecology of existing waterways. Land use for growing crops has increased by almost 600 per cent since 1700 at the expense of forest and woodland.

The document uses a series of maps to show the march of humanity in population terms - how it has spread itself across the globe.

The latest analysis shows areas with surprising population growth, Mr Bromley said. The Amazon basin, for example, has seen a significant increase.

High growth is seen in parts of the Central African rain forests. African and South American rain forests are of particular concern to researchers attempting to maintain plant and animal diversity.

The atlas also demonstrates how industrial development has spread and with it the chemical pollution of air and water. Use of fossil fuels and agricultural chemical inputs have contributed to this, with mining releasing toxic metals that find their way into soil and water.