Minor quibbles because I am an autistic know it all and I have to make corrections.
Umair has referred to the "Permian" extinction in several articles as "the last mass extinction". This is incorrect.
There have been five major “Mass Extinction Events” when over 75% of all life on the planet perished.
· Ordovician-silurian Extinction: 440 million years ago.
· Devonian Extinction: 365 million years ago.
· Permian-triassic Extinction: 250 million years ago.
· Triassic-jurassic Extinction: 210 million years ago.
· Cretaceous-tertiary Extinction: 65 Million Years Ago.
Unfortunately, the only one that most of the public knows about is the last one. Because it was the one that killed the dinosaurs.
In addition to these "Big Five" mass extinctions, there have been 6-10 smaller mass extinction events. Paleoclimate research has been able to establish that almost all of these events can be tied to rising CO2 levels in the atmosphere.
For a comprehensive look at paleoclimate science I recommend:
Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future by Peter Ward (2007)
Secondly, Umair references the Maya and the Romans. Linking their collapse to resource depletion forcing underinvestment and creating a feedback loop of decline.
The collapse of both of these civilizations was actually caused by Climate Change. In the case of the Romans a cooling climate. In the case of the Maya a cycle of droughts that lasted for several hundred years.
The example of Rome is particularly relevant to our situation today. I recommend the excellent book:
The Fate of Rome: Climate, Disease, and the End of an Empire by Kyle Harper (2017)
Consider this, in AD 150 the Roman project was at its peak. The population of the Mediterranean basin and Europe is believed to have been around 75 million people. Five hundred years later by 650 AD that population had declined by 50% and Rome had collapsed.
The old story was that this was the result of social decay, warfare, and governmental collapse. Harper, using new studies and data tells a completely different story. One of changing climate and multiple pandemics.
Starting in 150 AD the weather in the Roman world started getting worse, going from warmer to colder. It got progressively worse for the next 500 years causing multiple droughts, falling agricultural output, and famines.
This climate change was a disaster in and of itself, but it didn’t happen by itself. One of the points that Harper makes is that the Romans created a world where a pandemic could happen.
Cities with dense populations connected by highly trafficked trade links bringing in goods and people from all over the world made the Mediterranean a vast petri dish waiting for something deadly to fall into (sound familiar?).
In 165 AD something did. Starting in 165 AD the Antonine plague is estimated to have killed 7,000,000 in the first years that it hit the empire (165–180 AD) killing as many as 40% in many of the major cities.
After 165 AD plague was always happening in the Roman world and some of the “flareups” had fatality rates of up to 50% in places.
Harper’s point, is that while Rome may have had problems with governance; overshadowing everything was an increasingly hostile climate making it difficult to feed the population and, vicious plagues that depleted the pool of manpower available to do anything.
The parallels to the world we are facing today are obvious and compelling.
In the case of the Maya, this book by Dr. Richardson B. Gill "The Great Maya Droughts: Water, Life and Death (2001)" is now widely regarded as the definitive work on the collapse of the Classic Maya around 900 AD.
Although it was derided as “overly simplistic” and “reductively unicausal” by academic archeologists at the time (perhaps because Mr. Gill was an amateur archeologist without a doctorate), subsequent research has validated Mr. Gill’s theory. The Classic Maya civilization collapsed between 800 and 1000 AD due to a series of brutal 50-year long drought cycles.
He makes the point, which I have never forgotten, that in a severe regional drought event you cannot walk out of it.
We need water to live, a constant supply of it. We die without it in three days.
If you were living in a “premodern” city like Copan or Tikal and you had a year when almost no rain fell. All the wells ran dry, and all the rivers stopped running. Then you were dead.
All of you, everyone in the city, all at once.
There was no way to bring water to a city to save anyone. If you fled with the 5 or 6 gallons of water you could carry on your back, the furthest you would be able to walk would be about 100 miles.
If the affected area was larger than that, if the drought was regional. Then you were dead.
What Gill makes really, painfully clear is that droughts don’t just cause people to abandon cities. Drought has the power to kill cities and their whole populations.
A bad series of droughts, or just one megadrought” has the power to kill a civilization.
In China during the late 19th century droughts, there were provinces where 90% of the population died in a single year. Only those on the periphery managed to flee successfully.
If you live in Los Angeles, or Phoenix, or Las Vegas, or El Paso, or Dallas, or any one of dozens of cities that are almost certainly going to run out of water later in this century, this should concern you. What will you do if suddenly the taps run dry, the shower doesn’t work, and the toilet stops flushing? When there just isn’t any more water to be had, for any price?
