Climate and its change: OK, but what it is, really?
Whoho! I made a terrible mistake, beginning to speak of climate change and IPCC 2013 Technical Report, but forgot completely to define the meaning of the most important words: "climate", and its "change".
I might act as a traditional, dull gray professor and tell you "Oh, they're obvious: just have a look on page ... of the Report and you'll discover!" (Hidden meaning: "If you're not able to understand the Report definition, climatology is not for you.")
But if you skim through the Report you will find something like this:
"Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the
statistical description in terms of the mean and variability of relevant quantities over a period of time ranging
from months to thousands or millions of years. The classical period for averaging these variables is 30 years,
as defined by the World Meteorological Organization. The relevant quantities are most often surface
variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a
statistical description, of the climate system."
Have you understood? Really-really?
Well, I didn't.
Or better: logically I "understood" all. What gives me the gut shiver telling me I really did understood nothing is a 30-years period tells me quite nothing in relation with my daily experience. I'm ... (well, more than thirty but with an age which will soon be divisible by three and which currently is divisible by five squared but, ahem - better I don't add other constraints).
What could be the "mean" and "variability" of weather over 30 years? I'm lucky if I remember yesterday's (and, sure, I can tell quite for sure which the weather was on many past significant days quite far in time. But I have no direct memory of the continuous flow of weather over time. As most people I barely notice. So if one tells me the "mean" is this and that, I'll believe them on blind trust - but with no real guarantee.
Even though shorter than human average lifespan, a period of thirty years is very long!
If weather is so difficult to remember, may we find an analogy closer to experience?
I guess so. Indeed "many" analogies. One of the nicest I've found up to date comes (came? :-) ) (this is another suggestion about my current age) from our human biology: the "monthly" reproductive cycle.
It is said to endure on average 28 days (a short enough period to retain some memory of it). But in your specific case its average duration might have been a 29, or 27, or whatever else days.
Surely you do remember none of your periods was exactly identical to any other. As far as I remember, the only constant certitude was variability (on an increasing extent as age reached the peri-menopause phase).
Maybe, during your period you took basal temperature measurements in hope to find your maximum fertility period (or just out of scientific curiosity, as I did). If so, you also found no two consecutive days showed the same basal temperature. It also is possible to find interesting regularities: on ovulation and for the following 5/6 days basal temperature increases by a half or one Fahrenheit degree. If nothing reproductively relevant happened, the basal temperature switched back to its "normal" value, plus or minus some noise. The time difference between beginning of menstruation and ovulation in my case tended to be remarkably almost-constant in the beginning, 14 days. But once again you can see many small differences.
Now: our basal temperature is what bacteria living within of us (say, our intestinal flora) would honestly name "weather", if they only could speak. They would experience many temperature changes within of us, but they could identify the regularities I told you, and its variation: to them, our monthly period would look "climate".
In my case, age has crossed the subtle line between late fertility and peri-menopause. Periods have not yet stopped completely, but become much less regular. The length is now changing crazily from 19 to 35 days, with last year's average closer to 22 than my early age 29. There was a (massive) change. The most interesting part of it, in my feeling, is the more-than-wild behavior of basal temperatures, which in some phases (typically during menstruation, or what remains of it, and the following three-four days) runs up and donw, then up again, and down once more - with differences in excess of 0.75 °F. Does it have to do with an enhanced proclivity to hot flashes? Maybe: they happen.
But sure, it is a different climate for my intestinal flora. I'm sorry for them all: guess can do nothing to alleviate their troubles. There was then "climate change".
I mentioned many other natural processes may allow us to grasp the concept of "climate". Staying with physiology, and some of its strangeness, you may have notice the rate you lose hairs is not constant, but varies seasonally, with a peak around September-October in the Northern hemisphere (is this shifted in the Southern??). Not all people experience this seasonal change the same, and some claim it's typically "feale". Well, it isn't: we humans, as any other mammal, we human moult our bodyhair.
One year is longer than four weeks however. Sure from year to year there is a lot of change in intensity, duration and actual time span. But 365 are decidedly too long, and the problem too little, for us to concentrate on this detail the amount of attention necessary to get some memory.
So, 28 days are (as "I" feel) easy to remember, one year is not. Hair moult looks not a very good example, after all.
May we find something on a smaller time scale even than 28 days? Maybe yes. According to many studies not only women have reproductive cycles: men also have. Only, they do not take 28 days to complete: 24 hours are sufficient. In this time, various hormones and neurotransmitters change their concentration. Testosterone for example peaks in the morning. I've no data to share (and if some male friend is reading, may you please add your data/experience in comments?). But maybe, the perceivable effects are not so "obvious" than in women monthly period, and maybe if this is true the male reproductive cycle could not be that good example.
So, I stick with the "monthly" period - thanks, good lord Moon!
Now, imagine these 8 days take 30 years...
Simple, isn't it? ;-)
(Please, don't hurt me with the first object in your grasp field. Surely I'd devise, but consequences might be (for me) unpleasant, and prefer to avoid. Anyway, yes, if you feel "climate" and "climate change" are not so immediately obvious, you're not alone.)