Europe is baking. If current trends hold, this summer could be the hottest and driest on record. The heat isn’t subtle anymore. You can feel it. But the real story isn’t just about uncomfortable summers. It’s about speed.
The Speed of Climate Change vs. Geological Records
Computer models are great. They track where the world might be heading. But they aren’t the whole picture. To truly understand the danger, you have to look back. Not decades. Millions of years.
Geological records—sediments, rocks, ancient ice sheets, fossilized life—provide cause and effect without the guesswork. They show us how the climate has shifted before and what broke in the aftermath. Comparing human-caused global heating to past episodes of rapid warming reveals a stark truth. It’s not just the degree of heat that matters. Earth has been hotter in its 4.6-billion-year life.
The problem is the rate of change.
Aside from the immediate chaos following the asteroid that killed the dinosaurs 66 million years ago, carbon dioxide levels have never risen this quickly. In just a couple of centuries, we’ve spiked atmospheric CO2 faster than any natural event in recorded geologic history.
And the temperature climb? Unprecedented.
Current warming is 10 times faster than during the Palaeocene-Eocene ThermalMaximum, an extreme hothouse period 56 million years ago. It’s at least 20 times faster than the warming seen at the end of the last ice age.
Which Ancient Climate Period Will Our Future Resemble?
Looking into the past helps us predict the next few centuries. For 50 million years, the planet has generally been cooling. We are rapidly rewinding that process. A kind of “prehistorification.”
Your grandchildren won’t experience the climate that human civilization has known for millennia. They will inherit a new normal. Which one depends on us.
Scenario 1: The Late Pliocene
If emissions peak by 2040—and they really need to fall quickly after that—we might end up looking like the Earth did 3 million years ago. The Late Pliocene.
Back then, CO2 was lower than it is today (330-400 ppm). But temperatures were still 2.5°C to 4°C higher than pre-industrial averages. Sea levels sat 15 to 25 meters above current heights. These conditions could start appearing in continental interiors by the 2030s.
Scenario 2: The Miocene
If we fail to cut emissions fast enough, or if natural climate feedbacks kick in harder than expected, we risk rewinding the clock to the Miocene, 15-17 million years ago.
CO2 levels were moderate (400-600 ppm). But temperatures? Sky high. 6°C to 8°C above 1800s levels. Sea levels rose roughly 50 meters. The temperature jump suggests other heating factors we don’t fully understand were at play.
“Deciding how far back we will end up in our climate timeline is still within our gift.”
Scenario 3: The Early Eocene Hothouse
Satellites show an escalating energy imbalance. The heating rate is accelerating. This opens the door to the worst-case scenario: rewinding the clock by 50 million years. To the Early Eocene.
Blistering heat. Most of the planet uninhabitable for humans. A severe test of our species’ survival capacity.
How Much Hotter Will It Get?
There is no perfect answer. There is only trajectory.
The Persian mathematician Omar Khayyam looked back to understand the present almost a thousand years ago. “When I want to understand what is happening Today… I look back.”
He was right. We are ignoring the warning signs embedded in rock and ice. The speed of our current warming is the outlier. It defies the gradual shifts of the deep past.
We are living in a time of rapid transformation. The evidence is laid out. The choice, theoretically, remains.
Bill McGuire, professor emeritus at University College London, argues this in his latest work. The future isn’t fixed. It’s a race against the clock we’re running ourselves.
