hormesis hor·me·sis (hȯr-ˈmē-səs): a theoretical phenomenon of dose-response relationships in which something (as a heavy metal or ionizing radiation) that produces harmful biological effects at moderate to high doses may produce beneficial effects at low doses.
—hor·met·ic \-ˈmet-ik\ adjective
Salt, for example. We must have salt to live, but a fairly low dose will do. About 500mg per day according to previous thinking, now perhaps as much as 3,000mg per day is recommended. As consumption of salt increases it starts to do damage, and will eventually kill the animal that ingests it. Of course, the same can be said for water. We can’t live without it, but ingesting the illegal drug known as “ecstasy” can cause one to crave water to such an excess as to result in death. See, Anna Wood (1995) and Leah Betts (also 1995).
Small amounts of several heavy metals (zinc, copper and iron, e.g.) are needed for good health but are lethal at higher doses. One could say the same about food in general. Exerting stress on muscle tissue strengthens it, but too much stress on muscle tears it apart. I built up my ham strings with exercise, a form of stress; then tore one apart when I slipped on some ice. A little stress good, too much bad.
I say all this by way of introduction to criticism of the current hysteria on the part of global warming alarmists to the release of increased amounts of CO2 into the atmosphere.
At the beginning of the Industrial Revolution in 1750 the amount of CO2 in the atmosphere was about 3 parts per 10,000. Percentage wise, that is 0.03%. Say it this way: Three one-hundreths of one percent. Compare that to nitrogen-78%; oxygen-21%, argon-0.9%; water vapor varies from zero to 4%. Since the beginning of the Industrial Revolution the level of CO2 in earth’s atmosphere has increased from 3 parts per 10,000 to 4 parts per 10,000, or from 0.03% to 0.04%.
Water vapor is the most important greenhouse gas and it makes life on earth possible for most of its living inhabitants since without the retention of heat from the sun caused by the greenhouse effect of water vapor the surface temperature on earth would be a near constant minus 18º C, 0º F. All water outside of Yellowstone would be ice, and life as we know it would not be possible. Even the geysers in Yellowstone would become columns of ice. Old Faithful would be a column as high as the clouds, except there would not be any clouds.
CO2 is also a greenhouse gas but surely contributes much less to the greenhouse effect because it is such a small part of the atmosphere. CO2 is also necessary to life on earth; all plant life depends on it every bit as much as we depend on oxygen. CO2 might be said to be hormetic. In a high enough percentage of the atmosphere it might make the earth so warm as to make life just as unlikely as a complete absence of any greenhouse gas would do.
Without CO2 plants and trees would die, and so would we because it is the plants and trees that make the oxygen that we breathe. Increased CO2 no doubt also increases plant life, which in turn consumes CO2 tending to hold CO2 levels at the current low percentage of the atmosphere.
At some point, of course, all standing room on earth would be taken by tree trunks but thinking this way is known as reduction to absurdity, and is not worthy of serious concern. Given conditions in the streets of New York City in the year 1885 one could just as well have predicted that by the year 2000 the entire city would be covered over by a layer of horse manure 10 feet thick.
If we’ve only increased CO2 from 3 to 4 parts per 10,000 in the last 264 years, I’d say things are going along swimmingly and the wizards of brilliance on the U.S. Supreme Court who have agreed with the EPA to classify CO2 as a pollutant to be regulated should find something more constructive to do with their power.
Power in the hands of mortal human beings is itself an example of hormesis. A small amount exercised wisely can do good. Wielded arrogantly (and ignorantly) it tends to be abusive, and can do much damage to the flourishing of life on earth.