Regular readers know, I love graphs. I use them a lot. I tend to make them “scientifically,” i.e. the kind of graph you’d see in a scientific journal article. Just the fact, ma’am.
We’ve spoken before (as have many before us) of the fact that climate isn’t just about the average, it’s about the whole distribution (the probability distribution if you want to get technical).
We also emphasized that the tails of the distribution — the probabilities for extreme values (very very cold or very very hot, if we’re talking about temperature) can change profoundly when we shift the distribution left or right, without otherwise changing its shape; we illustrated this with July temperature in Moscow:
It set me to wondering, how do things look down under?
With winter snow in the northern hemisphere, we tend to forget the heat that summer brings to the southern half of the world. It can get pretty hot down there. The Guardian reports that Australia is entering the third day of another terrible heat wave, remarkable not just for how hot it is, but how much of the country it covers: basically, all of it.
A recent advertisement by Gillette argues for men to be better, the best we can be, in part by shedding the ugliness of toxic masculinity. It has sparked some controversy. The main objection I’ve heard is from men who reject the premise. Masculinity isn’t toxic, so fuck you!
How strong should the biceps be to cradle a man’s ego? Because nothing is more fragile when dropped back down to earth. The mass alone accounts for 80% of the weight of the world on her shoulders.
Probably the most commonly used way to estimate a trend in something is a mathematical process called linear regression. Basically, it means to fit a straight line [for those who must be pedantic, a flat hyperplane if we have multiple predictor variables]. In the case of time series, use time as the predictor variable and look for a linear relationship. If we find it, we declare “Trend!” and might even posit how big it is.
Why linear? Does anybody really believe that global average temperature since, say, 1970 has followed a straight line? Couldn’t it have wiggled around a little, just a little maybe — not noise, mind you, but genuine signal, real climate change rather than random fluctuation? Might it actually have accelerated, or even decelerated, or — heavens forbid! — taken a “hiatus”? Hell, mightn’t there have been brief episodes of all three, just not strong enough to be detected statistically (for a stickler like me)?
Of course. To my mind, the idea that as far as global temperature goes the climate — the signal, not the noise — followed a perfect straight line, is ludicrous.
The subject of this post isn’t the only new research on how ocean heat content has changed. Zanna et al. have taken a new approach to estimating it based on sea surface temperature history.
Of course knowing sea surface temperature at some point in time, doesn’t tell you the ocean heat content profile throughout the depths of the ocean at that time. But if you know the sea surface temperature history, and the heat-content-at-depth history, you can (at least theoretically) find a “transfer function” which tells you how the heat content profile depends on the time history of surface temperature. After all, the waters at depth were near the surface some time in the past and that’s where and when they got their heat.
It was suggested that sea level along the U.S. east coast can be affected by the el Niño southern oscillation (ENSO, usually just referred to as el Niño although that’s not quite correct usage). And indeed it does. I looked for its fingerprint in the data for the U.S. east coast, aggregated by my new method.