Science News has disheartening news for would-be explorers or lovers of virgin wilderness. The latest survey has found that no more than 3 percent of Earth’s land remains untouched by humans – and most of that isn’t protected:
The vast majority of land on Earth — a staggering 97 percent — no longer qualifies as ecologically intact, according to a sweeping survey of Earth’s ecosystems. Over the last 500 years, too many species have been lost, or their numbers reduced, researchers report April 15 in Frontiers in Forests and Global Change.
Of the few fully intact ecosystems, only about 11 percent fall within existing protected areas, the researchers found. Much of this pristine habitat exists in northern latitudes, in Canada’s boreal forests or Greenland’s tundra, which aren’t bursting with biodiversity. But chunks of the species-rich rainforests of the Amazon, Congo and Indonesia also remain intact.
“Hunting, the impacts of invasive species, climate change — these can harm ecosystems, but they can’t be easily sensed via satellite,” says conservation biologist Andrew Plumptre of the University of Cambridge. A Serengeti with fewer lions or hyenas — or none at all — may look intact from space, but it’s missing key species that help the whole ecosystem run.
What exactly constitutes a fully intact and functioning ecosystem is fuzzy and debated by ecologists, but Plumptre and his colleagues started by looking for habitats that retained their full retinue of species, at their natural abundance as of A.D. 1500. That’s the baseline the International Union for the Conservation of Nature uses to assess species extinctions, even though humans have been altering ecosystems by wiping out big mammals for thousands of years.
The team combined existing datasets on habitat intactness with three different assessments of where species have been lost, encompassing about 7,500 animal species. While 28.4 percent of land areas larger than 10,000 square kilometers is relatively free from human disturbance, only 2.9 percent holds all the species it did 500 years ago. Shrinking the minimum size of the area included to 1,000 square kilometers bumps the percentage up, but barely, to 3.4.
Overall the tally of ecologically intact land “was much lower than we were expecting,” says Plumptre. “Going in, I’d guessed that it would be 8 to 10 percent. It just shows how huge an impact we’ve had.”
You can read the Frontiers research here.