Post #3814656

2026-07-14 17:51 UTC

@level98@mastodon.social @freshstart@hachyderm.io @ColinTheMathmo@mathstodon.xyz The graph shows a standard z-score. The y-axis is not the magnitude of any standard deviation, rather it is the deviation (positive or negative) of that day's temperature from the base period's average temperature for that day (in units of the s.d. of base period temperatures for that day). This (among other things) corrects for seasonality, since the s.d. varies throughout the year. (math example: if during the base period from 1991 to 2020, day 150 had a mean of 10°C and a s.d. of 2°C, and day 150 of 2026 was measured to be 14°C, then the graph would show a y value for the 2026 line on day 150 of (14-10)/2 = +2 s.d.)

Replies (4)

@bradr@infosec.exchange 2026-07-14 18:04

@level98@mastodon.social @freshstart@hachyderm.io @ColinTheMathmo@mathstodon.xyz I can't see from this particular graph that there's a warming trend (though other graphs show that unambiguously), this one shows that we're in a hot year with temperatures 3.5 σ above the mean, when in another year at this time temperatures were 3.5 σ below the mean (the low point on the graph).

Open ##3814655
@bradr@infosec.exchange 2026-07-14 18:30

@level98@mastodon.social @freshstart@hachyderm.io @ColinTheMathmo@mathstodon.xyz That said, the graph itself does not really explain the problem without a lot of additional context. For example, one might ask, why should we set our hair on fire over a +3.5 s.d. anomaly in July of 2026, when we didn't set our hair on fire over the -3.5 s.d. the graph shows in some other July (probs from the 1998-2000 La Niña)? There is probs a reasonable explanation (e.g. there is an asymmetry where the entire graph hides the continuous warming that occurred before, during, after the baseline, such that the 2026 number represents a far larger injection of thermal energy than the reduction during the La Niña - but I'm guessing.) Anyone know?

Open ##3815125
@bradr@infosec.exchange 2026-07-14 18:31

@level98@mastodon.social @freshstart@hachyderm.io @ColinTheMathmo@mathstodon.xyz That said, the graph itself does not really explain to me the problem without a lot of additional context. For example, one might ask, why should we set our hair on fire over a +3.5 s.d. anomaly in July of 2026, when we didn't set our hair on fire over the -3.5 s.d. the graph shows in some other July (probs from the 1998-2000 La Niña)? There is probs a reasonable explanation, for example there is an asymmetry where the entire graph hides the continuous warming that occurred before, during, after the baseline, such that the 2026 number represents a far larger injection of thermal energy than the reduction during the La Niña - but I'm guessing. Anyone know?

Open ##3825493
@level98@mastodon.social 2026-07-14 21:38

@bradr@infosec.exchange @freshstart@hachyderm.io @ColinTheMathmo@mathstodon.xyz What I said... except your clarifying its on daily basis (which I was assuming, but did not make clear) and adding a calculational example... thank you.

Open ##3825495