Mad About Science: Ice Ages

By Brenden Bobby
Reader Columnist

There is no other fossil on record we’ve observed so intimately as the woolly mammoth, making it unique as far as extinct animals go. The primary reason for our familiarity with this long-dead species is the shockingly intact carcasses sometimes found frozen in Alaska and Siberia. Because of that, the woolly mammoth is the poster child for Earth’s last great ice age. Technically, however, “ice age” is an inaccurate term for what it was. We’re still in an ice age, just the warm part.

An ice age is an indeterminate amount of time (measured mostly by glacial and rock core samples) that has two phases: a glacial period and an interglacial period. A glacial period is when everything gets really cold, water levels drop and ice levels rise. An interglacial period is what we’re in now, which is considered a thawing when life can more readily flourish. 

Earth is moody and it swings wildly between these two states with relative frequency. These seem to happen and last anywhere from a few thousand to tens of thousands of years at a time. I bet you’re wondering why, or thinking I’m going to stumble into some trap that proves climate change is a hoax (sorry, it’s not.)

The idea that the Earth is and always has been a perfect spot for life is a silly concept; and the way woolly mammoths link into that is pretty telling indicator of the planet’s changeability. For one thing, the Earth has a funky orbit. Not only is it elliptical, like an egg, but Earth also wobbles “up” and “down” (though directional notions like “up” and “down” are irrelevant in space). This wobbly tilt creates our four seasons and is the reason why Australia is a lovely, hot paradise when we’re in the dead of winter. We may believe this to be the “perfect” condition for life, but the truth is that life had to work really hard to adapt to a climate like this. When it changes naturally over time, life adapts. When it happens abruptly, as it is right now, life struggles to adapt and we start seeing mass extinctions (Earth has had five that we know about).

Life can usually evolve in new forms that are “perfectly” suited to their changed environments, but the process can take millions of years. The big question: Can humans do that? 

We’re worried because so-called indicator species, which help us gauge the health of an ecosystem, are dying off. It’s like when you’re watching a horror movie, and the protagonists’ friends are getting diced up one after another around them. It makes you wonder: Is my favorite character — in this case humankind — going to make it out of this alive?

We aren’t entirely sure why the climate changed around the time of the woolly mammoth’s extinction, but it certainly worked in our favor then.

Here in the Northwest, we have one of the most dramatic connections in the world to the ice age. Most people around these parts are familiar with the Missoula floods; if you aren’t, you’re about to learn. 

For a period between 15,000 and 13,000 years ago, amid the last glacial period, our area sat at a unique temperature range: enough to create miles-high walls of ice, but also enough to keep liquid water running off warming glaciers. One particularly colossal reservoir, Lake Missoula, contained around 550 cubic miles of water held in place by a gargantuan ice dam near the current location of Missoula, Mont. 

A warming climate combined with the pressure of all that water caused the dam to break and unleashed a massive flood that dramatically ripped across the Northwest, pulling immense amounts of rock and glacial ice with it. This surging slurry of water and rock scoured out the basin of our beautiful lake. 

The most shocking thing about this is that it wasn’t a singular event; there may have been more than 40 such cataclysmic floods taking place as early as 1.5 million years ago.

Can you imagine standing on top of Schweitzer Mountain and watching an entire body of water roll up the Clark Fork River valley? Even more stunning, try to imagine it while sitting on the Hope Peninsula.

Basically, ice ages are awesome.

So, what could fling us into another glacial period? A surprisingly large number of things. A sudden increase in Earth’s volcanism spewing ash into our atmosphere and blocking the sun could drop temperatures sharply enough to trigger another glacial period — and, likely, widespread extinctions with it. A comet colliding with Earth could have a similar effect; even if the comet doesn’t have a dramatic immediate human casualty count, it could lower Earth’s atmospheric temperature enough to trigger another glacial period. Though we aren’t entirely sure, pumping more of our CO2 industrial byproducts into the atmosphere might mirror an increase in volcanic activity and have the same effect (or the opposite, causing desertification). Finally, something like a powerful earthquake altering Earth’s tilt just enough could trigger a move towards a glacial period.

Whatever it is, I hope it takes its sweet time, because snow tires are expensive and I’m not ready for a Westerosi Winter.

Before I depart, I wanted to thank the Clark Fork Library for letting me slum it here and write this article while I wait for my computer to update things. I’m so happy to have access to fiber optic internet not-so-far from home, because we’ll probably see another glacial period before I see fast internet at my house.