The sixth mass extinction is happening now, and it doesn’t look good for us

2 03 2022

Mounting evidence is pointing to the world having entered a sixth mass extinction. If the current rate of extinction continues we could lose most species by 2200. The implication for human health and wellbeing is dire, but not inevitable.

In the timeline of fossil evidence going right back to the first inkling of any life on Earth — over 3.5 billion years ago — almost 99 percent of all species that have ever existed are now extinct. That means that as species evolve over time — a process known as ‘speciation’ — they replace other species that go extinct.

Extinctions and speciations do not happen at uniform rates through time; instead, they tend to occur in large pulses interspersed by long periods of relative stability. These extinction pulses are what scientists refer to as mass extinction events.

The Cambrian explosion was a burst of speciation some 540 million years ago. Since then, at least five mass extinction events have been identified in the fossil record (and probably scores of smaller ones). Arguably the most infamous of these was when a giant asteroid smashed into Earth about 66 million years ago in what is now the Gulf of Mexico. The collision vapourised species immediately within the blast zone. Later, species were killed off by climate change arising from pulverised particulates suspended in the atmosphere, as well as intense volcano activity stimulated by the buckling of the Earth’s crust from the asteroid’s impact. Together, about 76 percent of all species around at the time went extinct, of which the disappearance of the dinosaurs is most well-known. But dinosaurs didn’t disappear altogether — the survivors just evolved into birds.

Read the rest of this entry »

Dawn of life

18 05 2015

Looking east toward the northern Flinders Ranges from Ediacara Conservation Park. © CJA Bradshaw

Looking east toward the northern Flinders Ranges from Ediacara Conservation Park. © CJA Bradshaw

I’ve had one of the most mind-blowing weeks of scientific discovery in my career, and it’s not even about a subject from within my field.

As some of you might know, I’ve been getting more and more interested in palaeo-ecology over the past few years. I’m fascinated by the challenge of reconstructing past communities and understanding how and why they changed. It’s a natural progression for someone interested in modern extinction dynamics.

Most of my recent interests have focussed on palaeo-communities of the Late Quaternary, and mainly in the range of 100 thousand years ago to the present. We’ve started publishing a few things in this area, and I can confirm that they’ll be plenty more to come in the following months and years. Despite plenty more to do in the youngest of palaeo-communities, I’ve now been bitten by the deep-time bug.

The giant Dickinsonia rex - a flat, worm-like discoid animal. © D. García-Bellido

The giant Dickinsonia rex – a flat, worm-like discoid animal. © D. García-Bellido

When I write ‘deep time’, I bloody well mean it: back to 580 million years, to be accurate. This is the time before the great Cambrian explosion of life popularised by the late Stephen Jay Gould in his brilliant book, Wonderful Life1,2. I’m talking about the Ediacaran period from 635-541 million years ago.

I’ve lived in South Australia now for over seven years, but it was only in the last few that I realised the Ediacaran was named after the Ediacara Hills in the northern Flinders Ranges some 650 km north of Adelaide where I live, and it wasn’t until last week that I had the extremely gratifying privilege of visiting the region with some of the world’s top Ediacaran specialists. If you have even the remotest interest in geological time and the origin of life on Earth, you should make a pilgrimage to the Flinders Ranges at some point before you die.

Read the rest of this entry »

Cartoon guide to biodiversity loss XXII

3 02 2014

Here are another 6 biodiversity cartoons while I prepare for yet another trip overseas (see full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here).

Read the rest of this entry »

%d bloggers like this: