Earth's 6th mass extinction imminent – report
MANILA, Philippines – Our planet is in the throes of another mass extinction, and humans are primarily to blame.
A review of studies and analysis of data showed that Earth is experiencing an alarming decline in animal species and populations, and this could be the "early days" of a sixth mass biological extinction event.
The review – published Thursday, July 24, in the journal Science – said that in the past 500 years animal population reductions and extinctions "may be comparable in both rate and magnitude with the five previous mass extinctions of Earth's history."
The major culprit? Human activity. "Anthropocene defaunation" – this is the term used by an international team of scientists, led by Stanford University biologist Rodolfo Dirzo, in describing this phenomenon.
Large mammals, such as bears and elephants, are the most vulnerable to this problem. These animals have lower population growth rates and need more space for their habitats, thus making them more susceptible to the effects of human activity.
Smaller animals – particularly invertebrates – are also under threat, and the review said this is the more problematic part.
As human population doubled in the past 35 years, invertebrate species have been halved.
The review also found out that geography plays a role, and the scientists saw that species decline is greater in tropical, biodiverse regions.
This impending mass extinction isn't only about the loss of animals – it will disrupt how ecosystems function, and how we humans live.
"We tend to think about extinction as loss of a species from the face of Earth, and that's very important, but there's a loss of critical ecosystem functioning in which animals play a central role that we need to pay attention to as well," said Dirzo.
For example, pollination and nutrient cycles can be disrupted; some pests can increase in number; water quality can suffer; and the most problematic, it could affect human health. Evolutionary patterns are also at risk with this disruption.
"Indeed, the effects of defaunation will be much less about the loss of absolute diversity than about local shifts in species compositions and functional groups within a community," the study stated.
Can we reverse this problematic scenario? The study said some measures such as mitigating the exploitation of these endangered animals and changes in land use can help, but in the long run, solutions are more complex.
"Moreover, several newer threats have recently emerged, most notably anthropogenic climate disruption, which will likely soon compete with habitat loss as the most important driver of defaunation," the study added.
In another review, also published in the same issue of Science, another group of scientists said there are ways of mitigating the loss of threatened species.
The review said "conservation translocation" can be a potential help in reversing this dangerous decline. In this method of species conservation, the team of scientists led by Philip Seddon of the University of Otago in New Zealand said establishing, rather than restoring, new "wilderness" is the best way forward.
This means that species are introduced in an area outside their historic range, rather than the traditional reintroduction to their native habitats.
They said that this is better because the usual goal of restoring wildlife populations and ecosystems to their original "untouched" state is "increasingly unobtainable."
The challenge here, Seddon said, is to maximize the positive outcomes and minimize the unintended consequences, such as invasive species.
The two review articles are part of Science's special issue on mass extinctions.
"If we are unable to end or reverse the rate of [species] loss, it will mean more for our own future than a broken heart or an empty forest," wrote Sacha Vignieri, one of the editors of the special issue. – Rappler.com