12 signs we're in the middle of a 6th mass extinction
- The planet is undergoing a sixth mass extinction - the sixth time in the history of life on Earth that global fauna has experienced a major collapse in numbers.
- Historically, mass extinctions have been caused by catastrophic events like asteroid collisions. This time, however, human activities are to blame.
- The primary culprits are deforestation, mining, and carbon-dioxide emissions that cause the planet to heat up.
- As a result, insects are dying off at record rates, animal species are experiencing "biological annihilation," and invasive aliens are driving native species to extinction.
The phrase "mass extinction" typically conjures up images of the asteroid crash that led to the twilight of the dinosaurs.Upon impact, that 6-mile-wide space rock caused a tsunami in the Atlantic Ocean, along with earthquakes and landslides up and down what is now the Americas. A heat pulse baked the Earth, and the Tyrannosaurus rex and its compatriots died out, along with 75% of the planet's species.
Here are 12 signs that the planet is in the midst of the sixth mass extinction, and why human activity is primarily to blame.
Insects are dying off at record rates. Roughly 40% of the world's insect species are in decline.
Earth appears to be undergoing a process of "biological annihilation." As many as half of the total number of animal individuals that once shared the Earth with us are already gone.
More than 26,500 of the world’s species are threatened with extinction, and that number is expected to keep going up.
A 2015 study that examined bird, reptile, amphibian, and mammal species concluded that the average rate of extinction over the last century is up to 100 times higher than normal.
In roughly 50 years, 1,700 species of amphibians, birds, and mammals will face a higher risk of extinction because their natural habitats are shrinking.
Logging and deforestation of the Amazon rainforest is of particular concern.
In the next 50 years, humans will drive so many mammal species to extinction that Earth's evolutionary diversity won't recover for some 3 million years, one study said.
Invasive aliens are a major driver of species extinction.
Oceans are absorbing a lot of the excess heat trapped on Earth because of greenhouse gases in the atmosphere. That kills marine species and coral reefs.
Species that live in fresh water are impacted by a warming planet, too.
Warming oceans also lead to sea-level rise. Rising waters are already impacting vulnerable species' habitats.
Warming oceans are also leading to unprecedented Arctic and Antarctic ice melt, which further contributes to sea-level rise. In the US, 17% of all threatened and endangered species are at risk because of rising seas.
If "business as usual" continues regarding climate change, one in six species is on track to go extinct.
Previous mass extinctions came with warning signs, too. Those indicators were very similar to what we're seeing now.
There's still some debate about whether we're truly in the middle of a sixth extinction. But there is agreement that the extinctions we're seeing now are our fault.
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