Habitat and species loss leaves just 3% of world's land ecosystems intact, study suggests

Smoke rises from an illegally lit fire in the Amazon rainforest reserve, south of Novo Progresso in Para state, Brazil, on August 15, 2020.

(CNN)Just under 3% of the world's land remains ecologically intact, with undisturbed habitat and minimal loss of its original animal species, a new study suggests.

The research, published Thursday in the journal Frontiers in Forests and Global Change, combined maps showing human damage to habitat with maps showing where animals have disappeared from their original ranges or are too low in number to maintain a healthy ecosystem to reach its conclusions.
The study paints a gloomier picture than previous analyses of wilderness areas, focused on human impact on habitat, which estimated that 20 to 40% of the earth's terrestrial surface has been little affected by humans.
    "Areas identified as functionally intact included east Siberia and northern Canada for boreal and tundra biomes, parts of the Amazon and Congo basin tropical forests, and the Sahara Desert," according to the authors.
      The researchers, led by Andrew Plumptre, from the Key Biodiversity Areas Secretariat and BirdLife International, based in the UK city of Cambridge, looked at three types of intactness to assess ecological integrity.
      These are habitat intactness, or the degree to which human activity has affected the land, faunal intactness, or the loss of animal species, and functional intactness, which assesses whether there are enough animals of the individual species for the ecosystem to remain healthy.
      "While wilderness areas are increasingly recognized as important for biodiversity conservation, few areas of the world remain that can be characterized as having outstanding ecological integrity," the authors wrote.
        "We found that only 2.8% of the terrestrial surface of the planet is represented in areas of 10,000 km2 or larger with low human footprint, no known species loss and no species known to be reduced below functional densities."
        Only 11% of the areas identified by the researchers as functionally intact are included within existing protected areas, the study notes. But, it adds, "many of the areas identified as ecologically intact coincide with territories managed by indigenous communities, who have played a vital role in maintaining the ecological integrity of these areas."
        Daniele Baisero, an author of the report and technical oficer for the Key Biodiversity Areas Secretariat, told CNN the findings had been surprising to the researchers. "There is much less ecological intactness than we previously thought," he said.
        But, Baisero added: "While the 3% figure that we found is low, the paper also highlights the opportunity to restore up to 20% of the land to close to intactness."
        The study, which did not include Antarctica, is far from the first to highlight the threat posed by humankind to the world's ecosystems.
        In January, a team of leading international scientists warned that accelerating climate change and biodiversity loss threatened the survival of all of the planet's species unless world leaders took urgent action.
        And recent research from the World Wide Fund for Nature found that the world's wildlife populations have fallen by an average of 68% in just over four decades, with human consumption behind the devastating decline.
        Some scientists believe a sixth mass extinction is gaining pace, and humans are in the driving seat, having already wiped out hundreds of species and pushed many more to the brink of extinction through wildlife trade, pollution, habitat loss and the use of toxic substances.
        "This study adds to other evidence that very little of our planet remains untouched or tainted by human activity," said Paul de Zylva, senior sustainability analyst for Friends of the Earth.
        "There are few truly wild places left and too many are under assault from oil and gas exploration, mining and land grabs. Our political and business leaders know what needs to be done to restore the natural state. They need to stand up to vested interests who seek to profit at the expense of both people and planet," de Zylva added.

        Targeted reintroduction

        In the study, the researchers suggest that some ecosystems could be restored by bringing back certain key animals.
        Reintroducing up to five important species, such as forest elephants or giraffes, to areas where the habitat remains undamaged but fauna have been lost could increase the percentage of the earth's land surface identified as faunally intact by up to 19%, using a minimum area of 10,000 sq. km., they say.
        An African forest elephant is pictured in the Lekoli River, Odzala-Kokoua National Park, Cuvette-Ouest Region, Republic of the Congo in August 2014.