A World Wildlife Fund (WWF) study says the populations of around 3,000 animal species' have declined over the past 40 years and humans are to blame.

The conservation group this week revealed wildlife population worldwide dropped by 52 percent from 1970 to 2010. The drop in animal populations is due to "uncontrollable human expansion," WWF reported.

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Man-made activities such as excessive emission of carbon dioxide, deforestation, oil and gas development, hunting and overfishing posed the biggest threats to nature.

Additionally, climate change, pollution, effects of invasive species and diseases are also factors in the destruction of natural habitats.

In 2012, the species of mammals (birds, fish, reptiles, and amphibians) fell by 28 percent since 1970, WWF reported. Advanced WWF methods in measuring wildlife populations show a huge difference in the result.

The conservation group publishes the "Living Planet Report" every two years. This is a science-based analysis that monitors the Earth's health and human activities affecting the planet.

Based on the report, the biggest losses occurred in tropical regions, particularly in Latin America, which lost about 83 percent of its wildlife in four decades.

According to the WWF study's editor-in-chief Richard McLellan, the "Living Planet" report is meant to represent the overall worldwide population data in the world.

WWF International Director General Marco Lambertini made it clear there is no room for complacency. Lambertini called on humanity to focus on sustainable solutions that counteract the impact of human actions on nature.

The damage is "not inevitable but a consequence" of the way people choose to live, Zoological Society of London (ZSL) Director Ken Norris said.

Norris also claimed there is still hope. "Protecting nature needs focused conservation, political will, and support from the industry," he added.

TagsAnimal populations, World Wildlife Fund, WWF