If You Don’t Like the Weather, Wait a Minute;
If You Don’t Like the Climate—Move

When, in conversation, people discover I work for a weather organization, the Mount Washington Observatory, one of two things happens. Especially if the weather is bad, I get blamed for it, or I get asked to explain what’s going on with all this “crazy weather.” By the way, it’s okay to blame me for the bad weather, as long as I get credit for the greater percentage of days when the weather is nice.

But to answer the second query is more difficult than it may at first seem. When we talk about weather, we are really talking about three things: weather, meteorology, and climate. The three are quite different in how we go about predicting or explaining them.

Weather is what is happening right now. Look out your window—is it sunny? Cloudy? Raining frogs? Hot? Is there an odd-looking funnel cloud roaring over yonder? Weather is, as New Hampshire State Climatologist Barry Keim likes to say, “what you talk about in line at the grocery store.”

Meteorology is the study and short-term forecasting of the weather. It’s what we think will be happening when we look out of our windows two or ten days from now. It is often about this forecasting where we hear the jibe, “It must be great to be a meteorologist; it’s the only job where you’re wrong all the time and won’t get fired.” Now, here, I do have to take a stand for my forecasting fellows. Our forecasting has become remarkably accurate, especially over the last few years; one to two-day forecasts are about 90 percent right, and over five days it drops off to about 50 percent— much less after that. Imagine if your favorite baseball player got a hit nine out of every ten trips to the plate, or even batted .500 over the course of a week. You’d lock him into a long-term contract, with all the perqs.

It might help to understand how forecasts come about. The most basic and important part of process is the hourly observation. At over 120 regional offices of the National Weather Service, and hundreds of other reporting stations around the country, readings of pressure, temperature, precipitation, humidity, cloud cover, and other weather stuff come in every hour. The result is a snapshot of what the weather is doing right now. If we put together a bunch of those pictures, we see a movie: how all the systems are interacting, where they’re moving. From this, we feed the data into some of the most powerful computers on earth, and they tell us what the movie is most likely to do over a certain period—hours to days. Your local meteorologist will add his or her knowledge of that specific area, and perhaps tweak the forecast to suit the terrain features.

Now, what about climate? That’s where all the debate seems to take place nowadays. Well, there’s a good reason for that. As with meteorologists, climatologists look at what has happened to try and predict what will happen. However, while the observation process has only been around in this country for about a century, climatologists have to look at millennia, and even millions of years. Since the dinosaurs didn’t carry around thermometers (at least, we have no evidence from the fossil record), we have to use “proxy” data—ice cores from the Arctic and Antarctic, silt deposits from the ocean floor, and “dendroclimatology”: the study of tree rings.

These records can tell us atmospheric composition from hundreds of thousands to possibly millions of years ago. Yet as with all data, they may be interpreted in many ways. And, as with weather forecasting, predicting what will come is open to much speculation. Several different forecasters for the same city may give dramatically different predictions for a certain day.

What makes predicting our planet’s future climate even more difficult is that the movie is very long and very slow. The last century has seen great changes in the levels of certain atmospheric chemicals--notably carbon, but also sulphur and nitrates--as well as a planet-wide temperature rise. A century is a blink on the climatologic scale; this makes it complicated to determine whether warming temperatures are anthropogenic (a very fancy word for “caused by humans”), or the result of a longer term cycle for which we just don’t have enough information.

If we have caused harm to our environment, it is certain we should intervene before irreparable damage is done. For those who don’t believe global warming is an issue to fret over just yet, there is still the question of whether we should do something about all that nasty stuff that we’ve put in the air anyway, just in case? Debate rages from the kitchen to the community to the congress, and even internationally (yeah, there was that Kyoto thing, right?).

I have often heard it said that folks may complain about the weather, but if it weren’t for changes in it, nine out of ten people couldn’t start a conversation. Maybe they only surveyed meteorologists. But with the present concerns over our changing climate, don’t be surprised to hear a lot more talk about it, even in the checkout line.