At least 97 percent of Earth’s land may no longer be ecologically intact and undisturbed by human presence. The damning statistic comes from a new study published in the journal Frontiers in Forests and Global Change this week.
The term "ecologically intact" has no strict definition, but it generally refers to areas of land that remain undisturbed by human activity and are still as abundant in animal life now as they were before industrialization. For this new study, an international team of scientists compared the natural ranges of thousands of mammal species today compared to the year 1500 CE, a time before the Industrial Revolution.
They found that only between 2 percent and 3 percent of Earth's land surface can be considered functionally intact – meaning they have seen no loss of animal densities below a level that would affect the healthy functioning of an ecosystem. Equally concerning, just 11 percent of these ecologically intact sites lie within environmentally protected areas.
“We know intact habitat is increasingly being lost and the values of intact habitat have been demonstrated for both biodiversity and people, but this study found that much of what we consider as intact habitat is missing species that have been hunted by people, or lost because of invasive species or disease,” Dr Andrew Plumptre, lead study author from the Key Biodiversity Areas Secretariat in Cambridge, said in a statement.
The areas of ecologically intact land can be found in eastern Russia, northern Canada and Alaska, the Amazon Basin, parts of the Sahara, and the Congo Basin. It’s striking that many of these areas overlap with territories that are home to indigenous communities that have played a vital role in maintaining and managing the ecological integrity of the areas.
These figures reached in the new research are worryingly lower than previous estimates. Past studies have suggested that between 20 and 40 percent of the planet's land remains untouched from significant human disturbance. However, the direct and indirect influence of human activity on natural environments is increasing with little sign of stopping any time soon. The ball started rolling centuries ago, but recent decades have seen a significant uptick in human activity disturbing wilderness areas.
As ever, though, there’s some hope. Human activity is encroaching on more and more land, but the study authors argue that up to 20 percent of the planet's land surface could be restored by the reintroductions of only a few species into remaining intact habitat.
“The results show that it might be possible to increase the area with ecological intactness back to up to 20% through the targeted reintroductions of species that have been lost in areas where human impact is still low, provided the threats to their survival can be addressed and numbers rebuilt to a level where they fulfil their functional role," explained Dr Plumptre.