05/22/2013 04:55 pm ET Updated Jul 22, 2013

The Icehouse Is Our Home

We are now living in an ice age, or rather what is called an Icehouse. All of human history has occurred in this Icehouse we now inhabit, which began 34 million years ago. I learned this recently from a remarkable podcast, an episode of "In Our Time" from the BBC. It's a panel where the host, Melvyn Bragg, assembles scientists or scholars and discusses a topic from any field. It might be anything: number theory, the caliphate in Persia, the Boxer rebellion, black holes, Shakespeare, the Stoics, you name it. It's a wonderful show. A recent one covered the successive Icehouses and Greenhouses our planet has endured. Here's what the scientists, from Britain's most esteemed universities, said, in brief:

If you go back millions and millions of years, global warming is an old recurrent story. The planet has gone from Greenhouse to Icehouse and back again many many times. For most of its history, the planet has been much warmer than it ever has been during the tiny sliver of time occupied by human history. In these predominant hot epochs, snow and ice were unknown. In fact, the planet has been in a Greenhouse state for most of its existence--it represents the norm. Ice Ages, or Icehouses, are much less common. The one we occupy has had warmer and colder periods, and the colder periods, when glaciers descend from the ice caps, are what we traditionally consider "ice ages." So we are living in a warmer portion of what is, in reality, a much longer Icehouse. The climate change we're seeing, as a result of our emissions, is tiny compared to the variations in temperature on the planet in the ancient past when CO2 concentrations were as much as 300 times denser than they are now.

But here's what's unprecedented: this current warming is happening at a radically fast pace--unseen in human history. In the past hundred years alone, the globe has warmed as much as it cooled over the previous seven thousand or so years. This figure is what the whole debate over global warming is about: this recent, comparatively meteoric rise in temperatures. It will melt the ice caps and pose a problem for human beings, who have adapted to the current ice age, with our coastal cities and everything else we've come to take for granted in terms of a cooler climate. So what we're seeing is a rapid return to the planet's ancient norm, driven by our own behavior and the CO2 we've poured into the atmosphere--something the planet itself has done all on its own, without our help, in the deep past.

Whether or not we care about what we're doing to the planet rests on purely selfish assumptions about what we don't want to lose, not what harm we are doing to the earth itself, which has thrived with far larger concentrations of CO2 in the atmosphere. (Dinosaurs and all the life forms of their era flourished during the Greenhouse that gave way to our current Icehouse.) So we aren't even scratching the surface compared to CO2 emissions from volcanic activity and the shifting of tectonic plates in the earlier periods of the planet's history.

In Our Time's hour of conversation among its guest scientists confirmed for me that the whole controversy about climate change is about our own self-interest, not about the welfare of the planet. In other words, both sides of the issue are speaking some degree of truth, though you would never know it from the tribal tone of the climate change debate. Yes, it's totally natural for the planet to get much, much warmer--if you go back millions and millions of years, of course. This time, though, we're the ones heating it up. We need to do what we can to preserve our own interests on the planet, but the planet doesn't require our abatement efforts. Ice Ages, like our current one, have endured for only about 20 percent of the time since the planet was formed. Short term, it's possible we could lower the levels of CO2 we produce. Long-term, the entire planet will become a jungle once again, regardless of what we do, unless we can figure out a way to regulate the climate in a massive way.

In Our Time's panel engaged in a fascinating, intelligent, non-political discussion that completely avoided disputes and simply described the facts. Listening to it, I longed for the same kind of calm, objective--non-competitive, if that's the right term--debate about whether or not we need to reverse the rising concentration of CO2 in the atmosphere. It is a choice, not a necessity. We can adapt to climate change and/or we can try to head it off--based on our calculations of what we stand to gain or lose. (Rising oceans don't bode well for a major coastal cities, for example.) On one side, there's a stubborn refusal to listen to the widespread scientific consensus that our own activity is the only way to explain the unprecedentedly fast rise of carbon dioxide (in parts per million). On the other side, you rarely hear about the fact that we aren't remotely close to concentrations of CO2 the earth knew during its lush Greenhouse era. Everyone is taking an oppositional stance and then digging in to promote one view or the other instead of recognizing how the truth lies somewhere in the middle, and that's where the fruitful discussion could be happening.

Bottom line: it's normal for CO2 to be much higher than it is now and by artificially returning the planet to its normal state we may actually be cutting short our Icehouse and preventing the next descent of glaciers from the poles. But do we want that? Are we ready to say goodbye to winter and our four seasons entirely? Greenhouse is the inconvenient norm for Planet Earth, yet the norm may be exactly what we don't want. We have to choose, because there's this little problem that the last Greenhouse ended halfway between the dinosaurs and the start of the human species. Humanity has known nothing but Icehouse.

We need to face the fact that we're the agents of it this time and that we need to act now to preserve what is, in terms of the planet's entire history, a rare intermission of relatively chilly climate. We have built our culture and civilization on the terms of this Icehouse. We need to keep our coastal cities dry and preserve the life forms that will perish if CO2 levels continue to rise.

Peter Georgescu is the author of The Constant Choice.
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