Earth’s Rock Record Warns of the Effects of Climate Warming

Some really terrific writing from Peter Brannen at The Atlantic:

We live on a wild planet, a wobbly, erupting, ocean-sloshed orb that careens around a giant thermonuclear explosion in the void. Big rocks whiz by overhead, and here on the Earth’s surface, whole continents crash together, rip apart, and occasionally turn inside out, killing nearly everything. Our planet is fickle. When the unseen tug of celestial bodies points Earth toward a new North Star, for instance, the shift in sunlight can dry up the Sahara, or fill it with hippopotamuses. Of more immediate interest today, a variation in the composition of the Earth’s atmosphere of as little as 0.1 percent has meant the difference between sweltering Arctic rainforests and a half mile of ice atop Boston. That negligible wisp of the air is carbon dioxide.

After that captivating lede, you quickly get to the real thrust of the article: that humanity is both failing to appreciate how devastating climate changes are for the inhabitants of Earth and, also, that we are seeing changes take place at far faster rates than scientists’ models had predicted. The result?

To truly appreciate the coming changes to our planet, we need to plumb the history of climate change. So let us take a trip back into deep time, a journey that will begin with the familiar climate of recorded history and end in the feverish, high-CO₂ greenhouse of the early age of mammals, 50 million years ago. It is a sobering journey, one that warns of catastrophic surprises that may be in store.

The near-to-mid term consequences of what humanity has been doing–injecting massive amounts of CO₂ into the atmosphere–can only really be appreciated when looking at the Earth’s geological record and trying to model what life might have been like in past periods. Critically, we find that:

[t]his sauna of our early mammalian ancestors represents something close to the worst possible scenario for future warming (although some studies claim that humans, under truly nihilistic emissions scenarios, could make the planet even warmer). The good news is the inertia of the Earth’s climate system is such that we still have time to rapidly reverse course, heading off an encore of this world, or that of the Miocene, or even the Pliocene, in the coming decades. All it will require is instantaneously halting the super-eruption of CO₂ disgorged into the atmosphere that began with the Industrial Revolution.

We know how to do this, and we cannot underplay the urgency. The fact is that none of these ancient periods is actually an apt analogue for the future if things go wrong. It took millions of years to produce the climates of the Miocene or the Eocene, and the rate of change right now is almost unprecedented in the history of animal life.

The decisions which are made over the coming decade or two will have compounding effects that will reverberate in ways that human minds are ill-suited to considered. It is critical to appreciate the need to mediate current actions which release CO₂ and actively work to mitigate such activities, while simultaneously planning for a world that is radically different from anything that the history of humanity has dealt with in its past.