Time Depth Perception
Remember that kid from elementary school, the one with the terrible depth perception? That kid was me. I fell down stairs, missed the next rung on the monkey bars, and could be counted on to drop the easiest pop fly. I eventually grew out of that, and these days my depth perception is probably as good as the next guy. My spatial depth perception, that is. On the other hand, my ability to judge and react to the depths of time remains terrible – just like everyone else’s.
This poor time depth perception just might explain humanity’s terrible environmental coordination. Basing all our plans on a paltry few decades of direct experience – or at most a century or two of records – we ignore the clear lessons of the deep past and insist on building (and re-building) in flood plains and fire-prone forests. We dam rivers and drain wetlands with little thought for the long-term consequences. On this continent, we have eliminated enormous populations of passenger pigeons and bison, overfished species after species – and still are stunned each time it happens again.
There’s no question that time has depth. Planet Earth is billions of years old. Events like the advance and retreat of ice sheets are so brief that they hardly register on the geological time scale, which is measured in Eons and Eras, each many millions of years long. By comparison, the Earth’s spatial dimensions are trivial. With our direct experience, we can grasp the size of the world, at least in some approximate way. I’m no mountain climber, but my Saturday hikes often take me six miles. That is greater than the vertical distance from sea level to the peak of Mt. Everest. And of course, we have tools at our disposal – cars and ships and airplanes – that allow us to travel to the remotest spaces on the planet.
In contrast, time travel is not an option. Our experience of time can’t be mechanically enhanced. It is simply gained the painful and old-fashioned way: by getting older, day by day, year by year. To improve our time depth perception, we must rely on science and imagination. The insights into the history of the Earth provided by geology, paleontology, and evolutionary biology are amazing. It has been millions of years since dinosaurs walked the Earth, but every child has a vivid imaginative picture of these incredible creatures in their minds, thanks to the painstaking work of scientists. And yet, how little thought do we grown-ups spare for the planet’s past!
Against all evidence, we believe that the world we grew up with is the norm, and that any changes we notice are mere temporary fluctuations that will soon pass. This belief in a stable natural world has never been less accurate – or more dangerous – than today. Climate scientists and ecologists have no doubt that climate change – or, more aptly, climate chaos – will transform the habitats of the planet in the coming decades. But they have surprisingly little confidence in their ability to predict what the world to come will be like. Indeed, climate change ecologists commonly use an ominous-sounding term: “the no-analog future.” That is, they believe that the future world will resemble nothing that we’ve ever seen.
This is in sharp contrast to how most of us picture the future. To the extent that we accept the likelihood of any climate-driven changes at all, we expect simple northward shifts of the habitats we know. Let’s say temperatures in San Francisco will come to resemble those in southern California today. Well then, we expect that the plant life of the Bay Area will become more like that around Los Angeles.
Unfortunately for this orderly picture, studies of past environments suggest that major climate changes shuffle species into new and unpredictable arrangements. The associations that seem so natural and permanent today – say, between pines and oaks in the Oregon and California foothills, or between sagebrush and juniper in the Great Basin – may fall apart in the future. What new arrangements will come . . . well, if we think we know, we are kidding ourselves. To prepare for this chaotic future world, the best we can do is to try to slow the pace of climate change and preserve as many species as we can, to give nature a chance to adapt with as little dislocation as possible.
Back in elementary school, when my depth perception finally started to improve, I figured out the trick to catching that pop fly. I learned to keep my eye on the ball and move to where it was going to come down. As environmental changes come hard and fast, will we be able to do as well – anticipate and adapt and keep our eye on the ball? Let’s hope so, because our very future will depend on our ability to master the art of perceiving the depths of time.