I wonder what it was like…

Our Fragile Planet has faced 5 great extinctions during it’s 4.5 billion year history.

  • First major extinction (c. 440 million years ago): Climate change (relatively severe and sudden global cooling) seems to have been at work at the first of these-the end-Ordovician mass extinction that caused such pronounced change in marine life (little or no life existed on land at that time). 25% of families lost (a family may consist of a few to thousands of species).
  • Second major extinction (c. 370 million years ago): The next such event, near the end of the Devonian Period, may or may not have been the result of global climate change. 19% of families lost.
  • Third major Extinction (c. 245 million years ago): Scenarios explaining what happened at the greatest mass extinction event of them all at the end of the Permian Period have been complex amalgams of climate change perhaps rooted in plate tectonics movements. Very recently, however, evidence suggests that a bolide impact similar to the end-Cretaceous event may have been the cause. 54% of families lost.
  • Fourth major extinction (c. 210 million years ago): The event at the end of the Triassic Period, shortly after dinosaurs and mammals had first evolved, also remains difficult to pin down in terms of precise causes. 23% of families lost.
  • Fifth major extinction (c. 65 million years ago): Most famous, perhaps, was the most recent of these events at the end-Cretaceous. It wiped out the remaining terrestrial dinosaurs and marine ammonites, as well as many other species across the phylogenetic spectrum, in all habitats sampled from the fossil record. Consensus has emerged in the past decade that this event was caused by one (possibly multiple) collisions between Earth and an extraterrestrial bolide (probably cometary). Some geologists, however, point to the great volcanic event that produced the Deccan traps of India as part of the chain of physical events that disrupted ecosystems so severely that many species on land and sea rapidly succumbed to extinction. 17% of families lost.

What was it like during these great events, I wonder?  I imagine as I’m sure most of us do, that these were horrific events, filled with terror and trauma.  Dead and dying beasts lay everywhere while those species that were to be their successors cowered, hidden, waiting for the sun to come out once more so that they, like some phoenix risen, could claim the world as their own.

Reality is far from that I fear.  Yesterday I read a chilling report:  A fifth of the world’s vertebrate species (i.e. mammals, birds, reptiles, amphibians, and fish) are now threatened with extinction, according to a massive new study by the International Union for the Conservation of Nature (IUCN); and the situation is worsening for the world’s wildlife: on average 52 species of mammals, birds, and amphibians move one category closer to extinction every year.

These are vertibrates; 3% of all lifeforms.  The situation isn’t much better for the other 97% either.  The study also reported on a number of non-vertebrate species types—not included in the overall analysis—finding, for example, that 14% of seagrasses, 32% of freshwater crayfish, and 33% of coral reef species are threatened with extinction. An earlier study, looking at a representative sample of plants, found that 22% of the world’s plant species are threatened with extinction.

One of the most threatened groups of species on Earth is the cycads, an ancient group of plants: 63% percent of cycads face extinction.

We are in the Sixth Great Extinction now and it looks like nothing is changing at all to us.  There is no fire, no rotting bodies littering the land, no massive die outs.  Just a few disgruntled fishermen who say they wish for the “good old days” when their catches were plentiful.  Just a couple of stories about the beetles that are killing all the ash trees.  Does anybody remember what the tree that the christmas carol “chestnuts roasting on an open fire” refers to looks like?

Great events that shatter our fragile planet look like this.  The fact that we don’t have a direct sense of a timespan that covers more than one generation is the reason why we don’t see the catastrophic change that’s occurring all around us.

I wonder what the cowering new species waiting to inherit the planet looks like…

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