Reply #31: The Five Percent Effect

[Dogmudgeon]

The difference between the freezing point of water and normal human body temperature is 66.6F. Five percent of that is just under three-and-a-half degrees. 105% of normal human body temperature (zero-based on the freezing point) is just about 102F.

At 98.6F, you feel pretty good; at 102F, you feel awful; without relief, you stand to suffer muscle damage, electrolyte loss, and minor brain damage. Without medical treatment, death will occur in a few days.

Ten percent brings the temperature to a little under 105F. Severe malaise, dehydration, and body pains develop quickly; brain damage is only a matter of a few hours, and death will occur within a a day.

Five percent UNDER normal brings you down to 95.3F. At that temperature, most people are in a state of medical "torpor", poorly responsive to stimuli and not oriented in their surroundings, and slowly becoming hypoxic. Unless normal body temperature is restored, it will continue to fall after a few hours, resulting in hypothermia and eventual death.

But you were discussing atmospheric gasses, weren't you?

Decrease the oxygen in the blood by 5% (called the paO2 or SaO2 in medical terminology) in most people, and they'll become lightheaded; sustain that drop, and they'll develop hallucinations, numbness, pins-and-needles sensations in their extremities, and heart arrhythmias.

Increase the carbon dioxide by 5%, and hypercapnia is the result. You get they symptom cluster of hypoxia, PLUS a reduced respiratory drive. Your blood pH goes rapidly alkaline as carbonate builds up in the red blood cells, reducing their ability to carry oxygen and a couple of ther electrolytes.

That's what 5% of something can do.

Global warming isn't causing a massive warm-up like putting a kettle on a fire -- it's two or four or five degrees over the course of a century. But it's enough to cause major climate changes. Greenhouse gasses are also increasing on a similar scale, but it is enough to change the climate. And all such changes have well-studied effects on climate and life; they have happened before, and we have seen their effects in the historical record, whether from tree rings, analysis of air trapped in amber or tar bubbles, fossils, or other "proxies".

Finally, the human contribution need not be overwhelming to throw a complex system such as world climate out of whack. Our contribution is most likely acting as a trigger. But it does not matter; we've done the deed, and the consequences are catching up with us. Now, if we had a low population, the damage would not be all that bad. We'd move to nicer areas and carry on. But we have a population nearing the limit of its resources. Even small-scale droughts cause large famines, which is one of the afflictions the people of Darfur are suffering today. A small, mobile, intelligent population could deal with it; a large, captive, tyrannized population can not.

Don't underestimate the small stresses on sensitive systems. Terrestrial ecology and human life alike depend on a dynamic balancing act of thousands, maybe millions, of interacting processes. Panic is the proper response to the threat of death from even the smallest of causes; the intelligent response to such a threat isn't to give in to the terror and flee, but to redouble one's efforts and use all available means to eliminate that threat. In our time, we face multiple threats, but with 6 billion highly-developed brains, someone surely knows how to cope!

--p!
Dr. Pangloss Meets Marvin the Paranoid Android -- and knows how to please the Ladies!