We are on the verge of a mass extinction since the dinosaurs were wiped out off earth's surface 66 million years ago, scientists warned. This would be the sixth mass extinction on Earth.
Depletion of more than 30 percent is seen in the population of species including vertebrates, birds, amphibians, fish, reptiles and other mammals as per the first comprehensive analysis.
"This is the case of a biological annihilation occurring globally," said Stanford professor Rodolfo Dirzo, co-author of a study published on Monday in the peer-reviewed US journal, Proceedings of the National Academy of Sciences (PNAS), as quoted by AFP.
Researchers were worried about the alarming elimination of species a decade ago.
The study provides crucial information regarding the danger to wildlife, mapping the dwindling ranges and populations of 27,600 species. Researchers combed through data of 177 mammals covering a period from 1900 to 2015.
The species examined were found to have lost around one-third of their original habitat.
The research revealed that 40 percent of mammals like orangutans, rhinos, gorillas and many big cats are surviving on 20 percent or less land they once roamed.
"Several species of mammals that were relatively safe one or two decades ago are now endangered," the study revealed.
Worldwide, this mass wipeout of animals is believed to be the sixth in the last half-billion years, which is said to be one of the worst since the three-quarters of life on Earth, including the non-avian dinosaurs-- wiped out 66 million years ago by a giant meteor impact.
Two vertebrate species are being put out of commission every year.
The depletion is found to be highest in tropical regions. In South and Southeast Asia, large-bodied mammals have lost more than four-fifths of their historical ranges. Lesser species are found to go missing in temperate zones.
As many as half of the number of animals that once shared our planet is no longer here, a loss the authors described as "a massive erosion of the greatest biological diversity in the history of Earth."
One of the known reasons for the wipe out is -- the rise of human species, which has more than doubled to 7.4 billion since 1960s.
According to the statistics provided by this study, there are less than 20,000 lions left in the wild, the number of cheetahs is less than 7,000, only 500 to 1,000 giant pandas, and around 250 Sumatran rhinoceros.
The reasons responsible for the fall in the wildlife are:
- Loss of habitat
- Overconsumption of resources
- Rise in pollution
- Invasive species
- Poaching of animals for their costly body parts
Polar bears will bear most of the brunt in comparison to other animals due to climate changes.
"The massive loss of populations and species reflects our lack of empathy to all the wild species that have been our companions since our origins," said lead author Gerardo Ceballos of the National Autonomous University of Mexico.
Beyond any moral imperative, there are practical reasons to rue the eclipse of animals, whether megafauna or smaller and less "charismatic" creatures, the researchers cautioned. The vanishing of a top-level carnivore or herbivore can have a cascading effect down the food chain, disrupting entire ecosystems, AFP stated.
Previous research revealed the ecosystems under stress can disintegrate due to rapid alteration.