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Earth After Humans
The world humans knew was ruined beyond recognition.
The year is 5025, at the start of the sixth millennium AD. We're in
an ice age. A mile-thick sheet of ice covers most of Europe, Asia,
and North America. Almost all of the world's living things,
including humans, went extinct. Earth will again be the blue planet
teeming with life, but humans will not be alive to see it.
Many civilizations came and went — Sumerian, Babylonian, Persian, and Mayan, to name a few. Each successive civilization flourished, puzzled about the ones that went before, and then fell. The Indus Valley Civilization lasted for a thousand years and then died because its climate changed. Easter Islanders started with a forested bird-nesting paradise and ended with a denuded landscape and a decimated population. How they got that way is still being debated. In the late Anthropocene — the time of humans on Earth — a single civilization covered the globe. They, too, collapsed.
A global collapse is worse than a local one, because survivors have nowhere to flee. A few people could hide in the wilderness and stay alive, but the vast majority were out of luck. The Inuit living in historically cold regions like Alaska and Northern Canada were the best adapted to survive the onset of an ice age. Unfortunately, the Inuit had nowhere to run, either. City dwellers tried to join them, and their range froze solid. If that weren't bad enough, the food chain died. The last humans perished when there was nothing left to eat. Humans could survive fire and ice, but not the loss of food.
From the beginning, humans lived on the natural bounty of Earth. They evolved in a world where one could capture a wild boar and roast it over a fire. Or discover a pristine sub-tropical island and bring a boatload of friends and spouses. Later, they learned to till the soil and grow crops.
Sadly, that world is gone. Boars are extinct, cropland is under ice, and every island has long since been spotted on satellite photos.
So, how did global warming lead to an ice age? Human abandon regarding atmospheric CO2 did indeed lead to warming initially. The Arctic Ocean became ice-free in summer. But it wasn't so much that the planet warmed as that stable climate patterns — the only patterns modern humans had ever known — became unstable. Yes, the Greenland ice sheet melted from the heat. But ocean salinity changes due to the meltwater triggered Siberian winters in Europe. Humans could have adjusted atmospheric CO2 levels to offset a natural tendency of Earth at that time to return to an ice age; they had that bit of terraforming within their power. Instead, humans dumped carbon into the atmosphere like there was no tomorrow and then suddenly stopped because they ran out of fossil fuel — as if no one knew that would happen. The jolt sent climate patterns reeling with nonstop weather calamities and economic chaos. Continent-sized regions dried up. Others flooded. Mass migrations became an engine of hate and political instability.
It gets worse. The last ice age never ended; we were just in the warm Holocene interglacial that had lasted 11,700 years. [1] Earth's climate is bi-stable between warm and cold and can flip with incredible speed. [2] Every year the snow line from those Siberian winters in Europe moved farther south. White snow on the ground reflects sunlight that would otherwise have heated a darker surface. Heat loss turns the weather colder, resulting in more snow in a runaway cycle. Once a cold snap took hold and gained momentum, it took just three years to wake the ice dragon.
Only the lower latitudes were left ice-free year-round. And even those regions were too cold for the original biologic forms to survive. Plants and animals that had survived habitat loss, pollution, invasive species, and harvesting by humans died from the weather. The combined stress and sudden onset were too much for the natural world, and the food chain died from the bottom up.
To be clear, the apex predator is doomed when the tiniest things at the bottom of its food chain perish. No amount of ferocity or cleverness can overcome it. When plankton disappeared, so too did the sharks.
Some things remained alive — a few weeds and scrappy things — but the vast majority perished. Bacteria in the ocean salted the atmosphere with methane and hydrogen sulfide making the air smell like a rotten egg. The ocean became a vast dead zone, depleted of oxygen. The world humans knew was ruined beyond recognition.
_________________________
[1] Glacial and interglacial periods. Online at:
https://energyeducation.ca/encyclopedia/Glacial_and_interglacial_periods
[2] The Atlantic, Jan 1998, "The Great Climate Flip-Flop", online at:
https://www.theatlantic.com/magazine/archive/1998/01/the-great-climate-flip-flop/308313/
Many civilizations came and went — Sumerian, Babylonian, Persian, and Mayan, to name a few. Each successive civilization flourished, puzzled about the ones that went before, and then fell. The Indus Valley Civilization lasted for a thousand years and then died because its climate changed. Easter Islanders started with a forested bird-nesting paradise and ended with a denuded landscape and a decimated population. How they got that way is still being debated. In the late Anthropocene — the time of humans on Earth — a single civilization covered the globe. They, too, collapsed.
A global collapse is worse than a local one, because survivors have nowhere to flee. A few people could hide in the wilderness and stay alive, but the vast majority were out of luck. The Inuit living in historically cold regions like Alaska and Northern Canada were the best adapted to survive the onset of an ice age. Unfortunately, the Inuit had nowhere to run, either. City dwellers tried to join them, and their range froze solid. If that weren't bad enough, the food chain died. The last humans perished when there was nothing left to eat. Humans could survive fire and ice, but not the loss of food.
From the beginning, humans lived on the natural bounty of Earth. They evolved in a world where one could capture a wild boar and roast it over a fire. Or discover a pristine sub-tropical island and bring a boatload of friends and spouses. Later, they learned to till the soil and grow crops.
Sadly, that world is gone. Boars are extinct, cropland is under ice, and every island has long since been spotted on satellite photos.
So, how did global warming lead to an ice age? Human abandon regarding atmospheric CO2 did indeed lead to warming initially. The Arctic Ocean became ice-free in summer. But it wasn't so much that the planet warmed as that stable climate patterns — the only patterns modern humans had ever known — became unstable. Yes, the Greenland ice sheet melted from the heat. But ocean salinity changes due to the meltwater triggered Siberian winters in Europe. Humans could have adjusted atmospheric CO2 levels to offset a natural tendency of Earth at that time to return to an ice age; they had that bit of terraforming within their power. Instead, humans dumped carbon into the atmosphere like there was no tomorrow and then suddenly stopped because they ran out of fossil fuel — as if no one knew that would happen. The jolt sent climate patterns reeling with nonstop weather calamities and economic chaos. Continent-sized regions dried up. Others flooded. Mass migrations became an engine of hate and political instability.
It gets worse. The last ice age never ended; we were just in the warm Holocene interglacial that had lasted 11,700 years. [1] Earth's climate is bi-stable between warm and cold and can flip with incredible speed. [2] Every year the snow line from those Siberian winters in Europe moved farther south. White snow on the ground reflects sunlight that would otherwise have heated a darker surface. Heat loss turns the weather colder, resulting in more snow in a runaway cycle. Once a cold snap took hold and gained momentum, it took just three years to wake the ice dragon.
Only the lower latitudes were left ice-free year-round. And even those regions were too cold for the original biologic forms to survive. Plants and animals that had survived habitat loss, pollution, invasive species, and harvesting by humans died from the weather. The combined stress and sudden onset were too much for the natural world, and the food chain died from the bottom up.
To be clear, the apex predator is doomed when the tiniest things at the bottom of its food chain perish. No amount of ferocity or cleverness can overcome it. When plankton disappeared, so too did the sharks.
Some things remained alive — a few weeds and scrappy things — but the vast majority perished. Bacteria in the ocean salted the atmosphere with methane and hydrogen sulfide making the air smell like a rotten egg. The ocean became a vast dead zone, depleted of oxygen. The world humans knew was ruined beyond recognition.
_________________________
[1] Glacial and interglacial periods. Online at:
https://energyeducation.ca/encyclopedia/Glacial_and_interglacial_periods
[2] The Atlantic, Jan 1998, "The Great Climate Flip-Flop", online at:
https://www.theatlantic.com/magazine/archive/1998/01/the-great-climate-flip-flop/308313/
Once a cold snap took hold and gained momentum,
it took just three years to wake the ice dragon.
it took just three years to wake the ice dragon.