Thursday, April 5, 2012

Weather and climate are not the same

Magnificent clouds and sun over the Willamette Valley

I'm constantly frustrated at the popular media's flawed insistence on interchangeably using the terms "weather" and "climate". They are NOT the same thing. Are they related? Yes. But they are not the same. The (intended?) result of this synonymizing is a relative dumbing down of the public's understanding of the two...and the subsequent dismissal of the realities of a changing climate. I can't tell you how many times I've heard people say something to the effect of "We set record low temperatures here for the month of (pick one)! You can't tell me the earth is heating up!"

Well...yes we can.

You see, it's really not the average global temperature that's the most interesting (but it's what many media outlets report and what many scoff at - "Psh! Who cares if the average temperature increases by 2-3 degrees?!"). Really, it's all about the extremes - the lows and the highs, not averages. So it's the variation around the average that really matters.

Think about it this way. Consider an average of 50 degrees F (close to the average annual temperature in Eugene, OR) derived from an average yearly low temperature of 40F and an average yearly high of 60F. If you're more of a mathematical learner, it'd look something like this:

(temp1+temp2) / number of temps = average temp

OR, from our example above,


But monkeying with the low and high can still produce the same result. For example,


A world in which this low-high scenario plays would be a very different one to live in than the one provided in the first example, no? And while I've exaggerated the low-high in the second example for demonstrative purposes, this low-high concept turns out to be incredibly important to the critters living in an area (i.e., the physiological thermal tolerance range of a species), especially for critters that are already living in environments at or near their ability to survive.

Now let's assume the average goes up a few degrees, as average annual global temperatures are predicted to do (see the most comprehensive report to date). Since it's really the low and high temperatures (the variation) that drive the average, doesn't it make sense for us to be more concerned about these two ends of the spectrum - the extremes? And as it turns out, those two ends are getting further and further apart with only a slight change (an increase) to the average. In other words, the variation around the average is increasing...and we're seeing more and more "extreme weather" events the world over. Welcome to the new norm.

But back to the topic at hand...

Weather takes place on relatively short timescales (e.g., days to months) whereas climate takes place on longer timescales (e.g., seasons and years to millenia). A newsy Q and A blurb from NASA's Global Climate Change program did a good job of explaining it in text. But for many, it's often more helpful to visualize an idea. This short animated video does a good job explaining the difference between the two.

Another analogy would be to think about weather as what clothes you might pack for a weeklong Spring vacation trip to Florida. I'd probably pack a couple of pairs of shorts and a couple of pairs of warmer clothes in case it turned off cooler (weather). But if I were planning to move to Florida, I'd likely get rid of most of my cold weather gear in favor of the shorts and shirt sleeves - so it's the proportion of cool and warm clothes (climate) that would matter to me more.

Perhaps if the popular media could get this little synonymizing nuisance cleared up, we might be able to better understand and accept these extreme weather events (anomalies that are becoming more commonplace) as part of our changing climate.

We all know smokers who live into their eighties, and health nuts that drop dead in their forties. Most people understand and accept anomalies in fields like health care and economics, and we need to do the same with climate issues. ~ Eric Fetzer

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