An alert reader wrote to ask us: “The word climate is used all the time, (usually as climate change). Presumably there is somewhere a strict definition of climate, but I have not found it. It seems to me that any discussion of climate change is pointless without a strict definition. My question is do you have a definition and if so what is it!!” And after a moment of gesticulating awkwardly about it being obvious, we did something too few journalists and commentators seem capable of in today’s “wired world”, a term here meaning “wireless”. We Googled “what is climate” and got a lovely set of definitive answers. Regrettably mismatched, though. And it’s not just pedantic fun and games, because it’s been a basic premise of intelligent thought and discussion at least since Socrates that you need to define your terms or you won’t get anywhere. As we aren’t on this file.

From National Geographic, under “All About Climate”, surely a bit of an ambitious heading, we got “Climate is the long-term pattern of weather in a particular area.” From NASA’s Jet Propulsion Laboratory, under the heading “Understanding Climate”, we learned instead that “Climate is the long-term state of the atmosphere at a particular location – in a sense, the ‘average weather’ over a long period of time. Climate varies significantly around the globe, and not randomly.” How long is “long-term”? How large is a “particular” location? Why only “in a sense”? That breeze you feel is from all the hand-waving.

Wikipedia feels, at least until the next edit, that:

“Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation.”

There you go: rigorously, from months to millions of years, but typically 30 years. And Britain’s “Met Office” says:

“Climate is the general weather over a long period. This can include rainfall, temperature, snow or any other weather condition. We usually define a region’s climate over a period of 30 years.”

Usually, mind you. And why 30 years? Why not 20? Or 50?

It might seem that we are just having fun here. And you can too by searching more examples. But we’re not joking around. On the contrary, if there’s such a thing as “climate science,” there has to be an agreed definition of the thing being studied as, say, scientists agree on what “hydrogen” is or, at the very least, a lively debate about what it is and why it matters. Because if you’re going to say there’s such a thing as “climate change” then you must be able to say, and know, what is changing.

If, for instance, “climate” means the local weather for the last 30 years then why do alarmists point to recent single years or single events and say they are proof of changes in “climate”? And if they have no scientific reason to pick 30 years as the time scale of climate, why not a thousand years? Or 30 days?

We are not just nitpicking. How you answer the scale question makes all the difference in whether you can hope to measure climate change in the first place. If there is a scientific principle that says “climate” is defined as the average weather for the whole planet over a thousand years then we have no idea if we are causing the climate to change, because we don’t have good enough data to measure what it’s doing. But if there is no scientific principle involved then please don’t tell us the science is settled. Meanwhile if the time scale is set at 30 years because that’s all the reliable detailed data we have, it’s not a scientific definition, it’s just an accident of history. And any claim about climate change based on such a definition is equally arbitrary.

Which brings us to the JPL’s ominous “and not randomly”. The implication is that something has suddenly changed lately. And again, it’s fair to ask whether it’s precisely what they mean, because if all they’re saying is that there are long-term trends, we agree. We’re not the “deniers” saying climate was essentially stable until 1988. It has been warming since 1850, though slowly, just as it cooled from around 1250 to perhaps 1750. And it’s been doing strange stuff since forever. On average, though, it’s a complicated picture because the Earth is a complicated place. Some places really do have fairly stable weather over long periods. Others, not even briefly. But they need something different. They need, essentially, random change or very little change until recently, and now ominous indications that some new factor has ruined the weather.

And another thing. As you’ve noticed, most of our definitions say climate refers to a specific locality. But the climate change scare is, of course, focused on that locality being the entire planet, and conditions changing in ways that are neither “random” nor good.

Even if we accept the 30-year time scale, trying to specify the Earth’s “climate” is a difficult task, rather harder than it sounds, and than alarmists often make it sound, since even the more restrictive definitions require us to take into account things like rain and wind. How would one summarize all the rainfall patterns everywhere over 30 years so as to permit meaningful comparison with earlier periods? It’s not much use having a model of the Earth that is every bit as big and complicated as the Earth because then it doesn’t simplify things sufficiently to get a mental grip on them, which has to be done or we can’t discuss the matter.

If you could create some kind of mentally comprehensible yet not oversimplified summary of the Earth’s climate from 1994 to 2024, then presumably you could also create one from 1964 to 1994, from 1934 to 1964 and so on back to the Crucifixion and beyond. And then you could compare these blocks to one another and see whether there were meaningful patterns, cyclical or linear, reassuring or frightening, including the alarmist one where it was supposedly pretty nice the whole way until James Watt, Henry Ford, Col. Sanders or some such miscreant threw the entire Earth out of balance and we got bad weather.

If you can’t, there’s nothing to discuss. If you can, and it turns out that weather was frequently awful, and that it has fluctuated since long before the steam engine, well, you’ve learned some useful things including that humans did not cause “climate change” and nor has whatever influence we may have had recently made it even worse than it used to be.

So yes, it’s worth defining your terms.