In the last 25 years, the amount of land protected for nature conservation has doubled. But despite that, nearly a third of the land has been seriously degraded by human activity, the study found.
That’s 2.3 million square miles of land, which is twice the size of Alaska. Most of the impact can be seen in highly populated parts of Asia, Europe and Africa.
The findings were published in the journal Science by researchers at the University of Queensland, University of British Columbia, and the Wildlife Conservation Society.
The worldwide loss of biodiversity caused by urbanization, road building, and other human activities led to the United Nations’ Convention on Biological Diversity treaty, signed in 1992.
All U.N. member states signed the treaty, and every country but the United States ratified it.
The researchers used maps measuring “human footprints” on the environment, a metric that includes factors like agriculture, population density, roads, and navigable waterways.
They found that 32.8 percent of the protected land is “under intense human pressure.” Just 10 percent of the land, mostly in remote areas of Russia, Canada and other northern countries, are “completely free of intense human pressure,” the researchers found.
Among the problems, the researchers note that “governments are overestimating the space available for nature inside protected areas.”
In 70 percent of countries, more than half of protected land is under intense human pressure, the study found.
Though the major loss of biodiversity continues to alarm scientists globally, the authors of the study see positive steps in keeping areas protected.
“We know protected areas work – when well-funded, well-managed and well placed, they are extremely effective in halting the threats that cause biodiversity loss and ensure species return from the brink of extinction,” study senior author James Watson, with the University of Queensland and the Wildlife Conservation Society, said.
“There are also many protected areas that are still in good condition and protect the last strongholds of endangered species worldwide. The challenge is to improve the management of those protected areas that are most valuable for nature conservation to ensure they safeguard it.”
Areas that are strictly protected are doing much better than areas that are not, the researchers found.
A key challenge will be for governments to increase how strictly protection areas are enforced while respecting the needs of local people.
The researchers also noted there are other factors besides the human footprint, like climate change, that affect biodiversity.
“Most importantly we’ve got to recognize that these jewels in the crown need support – there are some protected areas that are safeguarding nature and that still haven’t got any evidence of human encroachment in them,” Watson said.