The world’s population of mammals, birds, reptiles, amphibians, and fish has plummeted 53 percent since 1970, according to a World Wildlife Fund report released on Tuesday.
“Population sizes of vertebrate species have halved over the last 40 years,” the report said. “The state of the world’s biodiversity appears worse than ever.” During the same time, the world's human population has doubled, it noted.
The study used a Living Planet Index to measure more than 10,000 populations of the world’s vertebrates.
“These are the living forms that constitute the fabric of the ecosystems which sustain life on Earth,” Marco Lambertini, director general of WWF International, wrote in the report’s introduction. “We ignore their decline at our peril.”
The decline was most pronounced in the tropics, where the number of species fell from 3,811 to 1,638—a 56 percent drop. Latin America was hit hardest, with an 83 percent crash in species population.
Habitat loss and degradation, hunting, and fishing are the primary causes for the population crash in Latin America, the study stated. Climate change is the next biggest threat, according to the report.
Land and marine species have declined 39 percent each since 1970, with the steepest fall seen in sea turtles, shark species, and large migratory bird in the tropics and the Southern Ocean.
Three-quarters of freshwater aquatic life have disappeared over the past 44 years. “The main threats to freshwater species are habitat loss and fragmentation, pollution and invasive species,” the report stated.
This year’s WWF Living Planet Report found a steep and unprecedented drop in species, compared with the 28 percent decline the organization reported in a 2012 study.
One reason for the dramatic dip: new methodology deployed by the researchers.
“Year by year we have more data coming in, and it's responsible to include that data,” said Keya Chatterjee, WWF’s director of renewable energy outreach. “In previous reports, each species was given equal weight. Now a level of weighting that is proportional to the size of each taxonomic group—birds, mammals, amphibians, reptiles, fishes—and realm is given.”
While the report highlighted species decline, it also measured a growing human ecological footprint, described as the consumption of goods and the emission of greenhouse gases.
“More than 60 percent of the essential ‘services’ provided by nature, from our forests to our seas, are in decline,” the report stated.
That’s left the planet with a shrinking capacity to sustain its growing population.
WWF offered recommendations for alleviating the problem, such as shifting to more sustainable food and energy production.
Individuals can make a difference, Chatterjee said, by installing solar energy, reducing food waste, and switching to electric cars and other low-carbon vehicles.