Global wildlife populations have plummeted by 58% between 1970 and 2012, according to the latest Living Planet Report published by conservation group WWF on Wednesday.

The report — an analysis of data on more than 14,200 populations across 3,700 species of mammals, fish, amphibians, birds and reptiles — projected that if the trend continued, the world could lose more than two-thirds of wildlife by 2020.

Worst affected are species that live in lakes, rivers and wetlands — these freshwater dwellers have seen an 81% drop in populations over the past four decades, according to WWF.

The rapid rate of decline is attributed to rising human populations, habitat loss and degradation, hunting and climate change.

“Wildlife is disappearing within our lifetimes at an unprecedented rate,” Marco Lambertini, director general of WWF International, said in the report.

“We are entering a new era in Earth’s history: the Anthropocene,” he added. “An era in which humans rather than natural forces are the primary drivers of planetary change.”

WWF’s previous Living Planet Report, published in September 2014, found that biodiversity dropped by 52% between 1970 and 2010 — the latest data indicates that wildlife is being lost at an even more alarming rate.

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