A disturbing report released by the World Wildlife Fund Tuesday estimates that Earth holds less than half as many animals as it did roughly 40 years ago.
Global wildlife populations shrunk by 52 percent between 1970 and 2010, according to the group's biennial Living Planet Report. Tuesday’s numbers almost double 2012’s projections, suggesting wildlife decline is happening at a much faster rate than previously believed.
The report tracks population changes in more than 10,000 vertebrate species, according to a news release. It also examines consumption of goods and resources, greenhouse gas emissions, natural resource availability and other bookmarks of humanity’s ecological footprint.
The 2014 report concludes that humanity has left one massive footprint on wildlife populations.
“We’re gradually destroying our planet’s ability to support our way of life,” said Carter Roberts, president and CEO of World Wildlife Fund in the U.S. “We all live on a finite planet, and it’s time we started acting within those limits.”
The report breaks wildlife populations down into three major categories: Terrestrial, freshwater and marine. Terrestrial populations – like elephants, tigers, lions and rhinos – saw a 39 percent decline, as did marine animals. Freshwater animals – like frogs, salamanders, shorebirds and non-marine aquatic life – were hardest hit, with a population decline of 76 percent.
Tropical regions have seen the biggest wildlife declines geographically, especially in the Southern Hemisphere. The Neotropical region that the report says encompasses Central and South America had animal populations in 2010 that were 83 percent smaller than they were in 1970.
That doesn’t necessarily mean that 83 percent of all species alive in 1970 are now extinct in Central and South America, according to Vox. Rather, the vertebrate populations across the board in those regions are only a fraction of what they were four decades ago.
So who’s to blame for all this? The report suggests, in large part, it’s all our fault.
The fund assigns up to three primary threats to the habitats it pulls together for the report. Exploitation – including hunting and fishing, legally or otherwise – is the main culprit in diminishing wildlife populations, according to the study.
Other studies appear to support that finding. A study of African elephant populations released in an August issue of Proceedings of the National Academy of Sciences found poachers had wiped out nearly 100,000 elephants over a three-year period.
Poaching is believed to account for 65 percent of elephant deaths each year, according to the study. Only a decade ago, that number was 25 percent. Officials have begun airlifting elephants and rhinos out of highly poached regions in central and southern Africa and into more protected reserves.
A study released by The Pew Charitable Trusts in June also estimates that overfishing has cut bluefin tuna populations by 64 percent since 1970. And pollution from BP’s Deepwater Horizon oil spill in 2010 “could affect the reproductive potential of bluefin for decades,” according to the report.
Collectively, threats spurred by human development – including exploitation, habitat degradation, habitat loss, climate change and pollution – account for 93 percent of primary threats to wildlife around the world, according to the World Wildlife Fund report.
“There is a lot of data in this report, and it can seem very overwhelming and complex,” said Jon Hoekstra, World Wildlife Fund's chief scientist. “What’s not complicated are the clear trends we’re seeing – 39 percent of terrestrial wildlife gone, 39 percent of marine wildlife gone, 76 percent of freshwater wildlife gone – all in the past 40 years.”
The report finds that the U.S. and China alone account for nearly a third of the world’s total ecological footprint, which is defined by the fund as a measurement of "the area required to supply the ecological goods and services we use." And the world as a whole is operating at a pace well beyond our biocapacity, or "land actually available to provide these goods and services," according to the report.
At the rate society’s going, the fund says it would take one and a half Earths to meet our continuously growing demands on land and resources.
“This continuing overshoot is making it more and more difficult to meet the needs of a growing global human population, as well as to leave space for other species,” the report says. “Adding further complexity is that demand is not evenly distributed, with people in industrialized countries consuming resources and services at a much faster rate.”
On a less depressing note, high-income countries like the U.S. actually have managed to increase domestic biodiversity through conservation efforts. Mammal populations were up 80 percent in North America in 2010, and bird populations increased more than 460 percent in the region since 1970.
“Things look so worrying that it may seem difficult to feel positive about the future,” Marco Lambertini, international director general of World Wildlife Fund International, writes in the report. “Difficult, certainly, but not impossible … it is by acknowledging the problem and understanding the drivers of decline that we can find the insights and, more importantly, the determination to put things right.”