Earth's Climate Swings

This precious planet of ours has gone through numerous changes in its climate, over its lifespan (4.5 billion years). For most of that time, the climate was not one that we humans (or most other existing plants and critters) could even have survived in. More often than not, the atmosphere was composed of gases that would have choked us: carbon dioxide, sulfur dioxide, methane, and other suffocating gases.

 

The temperature swings in Earth’s past are another factor that made our type of life impossible. At times the entire planet was covered with ice and on other occasions it was so hot that we would have turned into grilled meat in short order.

In fact, only in the last 500 million years have climate conditions allowed any form of life larger than single-celled microorganisms to survive. And for most of that time period, our species could not have endured. As recent as a few million years ago the climate swung wildly from icy cold to blazing hot, every few thousand years.

In stark contrast to that history of nasty environmental swings, the last 10-15 thousand years on Earth have been unusually stable, mild, and gentle. Since our written history extends only a few thousand years back, we have no comprehension of the tough conditions that our deep ancestors had to contend with.

We barely have an understanding, for example, that a super volcano exploded in Toba, Indonesia some 75 thousand years ago, and came close to wiping out the human species by creating massive climate change. It led to an extended volcanic winter, wherein the worldwide temperature dropped some 5-9^oF. Most humans died. Only a few thousand of our ancestors managed to squeeze through, hunkered down in Africa. It was the largest super volcano in the last 25 million years.

In a similar fashion, we are not really able to appreciate the kind and gentle climate that Earth has given us in the last few thousand years, that has allowed our population to swell to seven billion people.

Maybe that’s partly why so many people seem blissfully ignorant of the fact that the current benevolent climate period is drawing to a close. Modern Homo sapiens has enjoyed a friendly world and has come to take it for granted. We expect the good times to keep rolling on, but it ain’t necessarily so.

In fact, the good times are ending. The tragic irony of the situation is that the current swing towards an unpleasant climate is not being caused by a crashing meteorite, a volcano, or a shift in the planet’s magnetic axis, but by the dominant species that has most benefited by the recent idyllic situation: us. Climate change this time around is our responsibility. We’ve pumped so much carbon dioxide into the atmosphere that the benevolent times are over. Polar ice is melting, the temperature is rising (along with the sea level), and superstorms like hurricane Sandy are becoming commonplace.

The future is very uncertain, and it’s being pushed toward the scary side by our stupidity and inaction. Hang on, folks… the ride is about to get bumpy.