资源环境科技发展态势分析平台

By Layal Liverpool

Daniel A. Leifheit/Getty

Humans have spread to most parts of the planet, and now researchers have calculated that only a fifth of ice-free land on Earth is free of our influence.

A team of researchers led by Jason Riggio at the University of California, Davis, analysed four separate maps showing global human influence around the world at different times between 2009 and 2015. They then created one composite global map highlighting areas where people have the least influence.

The researchers defined areas of very low human influence as land that is either not occupied or used by people, or that only contains low density populations of indigenous peoples. These are primarily wilderness areas where humans are visitors, not residents, they say.

After excluding the estimated 10 per cent of Earth that is currently ice-covered land such as Antarctica and most of Greenland, or glaciers elsewhere in the world, and calculating the level of agreement between the four maps, they found that 21 per cent of the remaining land on Earth has very low human influence.

Low human influence land – areas that aren’t heavily used or occupied by people, such as pastoral landscapes with low densities of people and livestock – makes up about 46 per cent of the planet’s non-ice covered land.

Most of the low human influence areas on the planet are really cold, high or dry areas of land, such as arctic landscapes, montane areas or deserts. In contrast, only about 10 per cent of grass lands and dry forests have low human influence, says Riggio.

The analysis suggests “the overall trend is that we continue to lose natural landscapes and overall human influence is increasing globally”, says Riggio.

“A global human influence map is critical to understand the extent and intensity of human pressures on Earth’s ecosystems,” says Riggio. Highlighting the few remaining areas on Earth with little human impact could also help governments and organisations to plan and prioritise which areas of the world to protect.

Journal reference: Global Change Biology, DOI: 10.1111/gcb.15109

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