Crocodiles and climate change

Remember Tick Tock, the crocodile in the Disney animated movie "Peter Pan"? He had swallowed an alarm clock, and you can always hear him coming.

Tick Tock is always coming for the evil Captain Hook. Ever since Peter Pan cut off Hook's hand and fed it to the crocodile, Tick Tock has been pursuing Hook relentlessly, wanting nothing more than to gobble up the rest of him.

Unfortunately for Tick Tock (and fortunately for Hook), he's a very big crocodile and moves extremely slowly. So Hook always listens for the sound of a ticking clock, and when he hears it, he knows it's time to get moving before the always-hungry Tick Tock catches up with him.

Well, kids, here's some bad news. We have our own Tick Tock heading our way. It's called climate change. It's moving slowly, like the crocodile, but it never stops.

We don't notice changing climate from day to day because of short-term fluctuations in weather and medium-term seasonal weather patterns like shifts in the jet stream. So it's easy to believe that the climate isn't really changing at all. But it is.

Setting aside all the weather-related highs and lows, how fast is our climate changing? And will it, like the slow but steady Tick Tock, ever catch us and eat us?

One way to visualize climate change is to compare the rate that our own hometown is warming with the rate that we would warm up if we headed south to Orlando, Fla., home of Disney World and our friend the ticking crocodile.

Let's compare the numbers. First, if we stay in just one place, how fast will our climate warm?

According to NASA scientists, the average temperature in the United States is increasing by 0.37 degrees Fahrenheit every decade. Rounding off, that's about 0.04 degrees per year. Doesn't sound like much, right?

Well, that's 10 times the rate of the fastest global warming period ever recorded or estimated by scientists by looking at geological evidence. It's incredibly fast as Earth's history goes, but not something you'd notice from year to year.

Now let's look at how fast you'd warm up if you headed south from Pittsburgh to Orlando to visit our friend Tick Tock.

Orlando's average temperature over the course of a year is 73 degrees. Here in Pittsburgh, it's 52 degrees. So that's a difference of 21 degrees.

Orlando is 781 miles south of Pittsburgh. Do the math, and you'll see that for every mile that you go south, the temperature increases by, on the average, 0.027 degrees.

Well, that's interesting! Go south for a mile and a half and the temperature increases by 0.04 degrees. Don't want to leave home? No problem. Just wait a year and the temperature will also increase by 0.04 degrees!

In other words, for every year that goes by, it's as if you, your family, your house, your yard and your entire neighborhood all slid southward by a mile and a half.

How fast does something move if it travels 1.5 miles per year? Not fast at all if you're sitting and watching it, assuming that the chair that you're sitting in is unaffected by climate change and is not also moving southward. A mile and a half per year is roughly 22 feet per day. That's 11 inches per hour.

Now, if you see that your house is sliding south at 11 inches per hour, you might think that's nothing to worry about, right? It's about the width of a toothpick every three seconds. Get down on your hands and knees and look with a magnifying glass and you'd see your house grinding very slowly through the dirt. Step back a couple of steps, though, and you won't see it.

But such little movements add up. Sure, you can't see your house moving south. But go to bed at night, and you'll wake up in the morning to find that you're 4 or 5 feet closer to Disney World than when you went to bed. A year later you'll be a mile and a half closer to the sunny South.

Seventy five years from now, you and your house will be, more or less, at the latitude of Washington, D.C. Not a bad place to be. But as you sit on your front porch, you'll probably think back to when it used to snow in the winter. Yup, you say, we just don't see snow much anymore. I remember when we used to go sledding in the winter and the snowdrifts were up to here.