I talk a lot about trend. It’s important. Climate change is, after all, really about the trends — the changes that persist, that portend what we might expect to come.
Weather includes the fluctuations around the trend. They’re always there, things like temperature just won’t stop fluctuating. That’s why, if we want to know how climate is changing we need to attend to the trends. But if you want to deceive yourself, if you’re so determined not to believe nature that trends give you the “willies” and make you cringe, you’re likely to sieze upon the fluctuations and say “Aha!” It was cold!! See — a snowball!!!
Senator Jim Inhofe (R-OK) isn’t the only one who does that. So do Anthony Watts, purveyor of the WUWT blog, and Roy Spencer. Their latest seizures have them pointing out how cold it was — not over the globe this last decade, but over the lower 48 states of the U.S. at 7:00 A.M. yesterday (Dec. 18, 2016). Yes, 2% of the globe for one hour.
Here’s the proof:
Wow! Colder yesterday than all last winter (for 2% of the globe)!! And it’s not even winter yet!!!
Or is it? Perhaps they don’t get the difference between the astronomical definition of “winter” and its climatological definition. If we plot monthly average temperature by month of the year, then winter — the coldest three months of the year — clearly includes December.
But, let’s not quibble about that. Instead, let’s think about what Spencer’s/Watts’s graph actually indicates. They really should have thought about that.
Clearly they want to impress people with how amazingly cold it was yesterday. But when you think about it, and look further back than just a single year so you can get some context, that’s not what the graph shows at all. What it really shows is how hot the U.S. was last winter. Here’s the wintertime (done right, Dec-Jan-Feb) average temperature for the lower 48 states of the U.S.:
Last winter was the hottest on record. And that is what Spencer’s/Watts’s graph actually shows. Apparently they don’t get that. By and large, neither do their readers.
The reason last winter was so hot in the U.S. is the combination of trend and fluctuation. Fluctuations go up, they go down, and it so happens that last year they went up. That alone would have made last year a hot one in the U.S., but in addition to the upward fluctuation there is also an upward trend. When you put the two together, not only can you get a hot year, you have a pretty good chance of setting a new record. Like last year.
This year, U.S. winter isn’t likely to be as hot. The trend is still there, but the fluctuations probably won’t be as high as last year’s. That means that we’ll have to endure a lot of stupidity, ranging from “not as hot as last year!” to “colder than all last winter!!!”
If only some of those people would put some actual thought into it. Am I just hoping for too much?
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