The world's wildlife populations have declined by more than 50 percent since 1970, according to a report published today by the World Wildlife Fund (WWF). In its biennial Living Planet Report, the WWF finds that the largest declines have occurred in tropical and low-income regions, where biodiversity has suffered due to increasing resource demands from high-income countries.

"We're gradually destroying our planet’s ability to support our way of life," Carter Roberts, WWF president and CEO, said in a statement Tuesday. "But we already have the knowledge and tools to avoid the worst predictions. We all live on a finite planet and it's time we started acting within those limits."

The group's Living Planet Index — a representative sample of more than 10,000 populations of birds, mammals, reptiles, and fish — decreased by 52 percent between 1970 and 2010. That marks a far greater decline than previously believed, partly due to more available data. The WWF's previous Living Planet Report, released in 2012, found that the index declined by 28 percent between 1970 and 2008. Freshwater species saw the steepest decline between 1970 and 2010, dropping by 76 percent, followed by marine and terrestrial species, which both fell by 39 percent. Much of this decline has been driven by unrelenting demand for natural resources, which destroys natural habitats and ecosystems, and has been compounded by climate change.

The report also measures each country's "ecological footprint," which highlights regional differences in resource use. Kuwait was found to have the largest ecological footprint per capita, followed by Qatar. The US has the eighth largest per-capita footprint, but is second only to China in the aggregate. India, Indonesia, and some other low-income countries have sustainable per capita ecological footprints, but the world as a whole would still require 1.5 Earths to sustain its current resource consumption.

"If all people on the planet had the footprint of the average resident of Qatar, we would need 4.8 planets," the WWF said. "If we lived the lifestyle of a typical resident of the USA, we would need 3.9 planets."

The outlook is certainly grim, but the WWF says there's still a chance to reverse course if businesses and politicians make conservation a priority.

"We need leadership for change," Marco Lambertini, director general of WWF International, wrote in the foreword to the report. "Sitting on the bench waiting for someone else to make the first move doesn’t work. Heads of state need to start thinking globally; businesses and consumers need to stop behaving as if we live in a limitless world."