From early maths lessons I remember there are three ways of measuring averages: mean, mode and median. I also remember upper and lower quartiles and have a vague recollection of standard deviation. I am no mathematician.
But I have done a lot of biology and one thing I am certain of is that life systems care very little about averages. Life is about maintaining equilibrium, and uses extremes to regulate and perform control operations between systems. I am referring to systems like hormone, nervous or immune regulation, where triggering happens when thresholds of chemicals are breached so invoking a response.
In the current debate on climate change the politicians are constantly referring to average temperature rises. Like in the body, this is largely irrelevant. It is the extremes we need to be worried about. We may well be able to survive a summer where the mean rise in temperature is 3 Celsius but what will happen if 1 of those days is 10 Celsius above the mean. The most recent heat waves have killed hundreds of thousands, and climate change seems to be promising even greater extremes.
The climatologists are under-egging the problem we face. Predictive models of future mean temperatures are not taking into account the seriousness of extreme cases. Life systems are extremely fragile, ecosystems are easily disrupted. Maybe there is a bacteria in the soil that is only just managing to out-compete a much more deadly one, a 10 Celsius rise on one day could wipe it out and an epidemic break out that kills all adults between 25-50. Then we'd be really screwed.
Edge cases are the most revealing when looking to the future. We're lacking imagination.
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