From National Geographic News: “An instrument near the summit of Mauna Loa in Hawaii has recorded a long-awaited climate milestone: the amount of carbon dioxide in the atmosphere there has exceeded 400 parts per million (ppm) for the first time in 55 years of measurement—and probably more than 3 million years of Earth history.”
The graphics below suggest that we are about 10,000 years into a warm spell on planet Earth. Prior to the last ice age we had about 17,000 years of relative warmth before things started to go down hill. If 17,000 years is about right for our current warm spell, then we have only 7,000 years left in our Garden of Eden. But we are clearly polluting our environment. The big difference now is that in the warm spell that took place between 132,000 and 115,000 years ago there were only a million or so homo sapiens around and no polluting industry. Now we have almost 8 billion modern humans and an industrial society.
It’s clear that whomever coined the term “Global Warming” coined a misnomer because it looks as though our atmosphere was warmer 130,000 years ago. The popular phrase should be “Global Polluting” shouldn’t it? Then the nay-sayers might accept the problem and take some responsibility for it. Otherwise human beings may not be around to have the next ice age.
I’ve added some benchmarks to the graph below which shows the patterns of warming and cooling of the Earth for the last 400,000+ years. The warming and cooling of the Earth is caused by a very subtle movements closer and farther from the Sun in our eliptical orbit. This is not man-made. The last ice age took longer than the three previous ice ages shown in the graph which is based on chemical analysis of core samples from the Vostok ice sheet in Antarctica. Two benchmarks are the demise of H. erectus and Neanderthals based upon the fossel record. These two species of Homos died off near the ends of two ice ages. Imagine what it would be like for us if the biosphere was 13 degrees colder on average than it is today. Back then their only refuge was a chilly cave or to head south. No wonder humans got their start in Africa.
Our current understanding of human history only came about since 1970 when nucleic acid hybridization became a tool for understanding the divergence of genes among all lifeforms. The rate of hybridization of two strands of DNA is a function of complimentarity of the Watson-Crick double helix.
From the last full cycle it appears that warm spells last about 18,000 years whereas the last ice age lasted about 97,000 years. It looks like archaic Homo sapiens survived two ice ages whereas Neanderthals only survived one. But our human male Y chromosome was passed on from H. erectus while the earliest date of discovery of mitochodrial DNA was during the time that archaic H. sapiens roamed sub-Saharan Africa. The mitochondrial DNA genome is inherited from mothers, not fathers; likewise in plants, chloroplasts are not carried in pollen when the female part of the plant is fertilized.
This is all very mind-boggling to consider. Will scientists have the answers for how to deal with the next ice age? Yup! Will politicians cooperate? We’ll just have to wait and see.
Graph of CO2 (Green graph), temperature (Blue graph), and dust concentration (Red graph) measured from the Vostok, Antarctica ice core. The shifts between hot and cold periods is thought to be controlled by the the Milankovich cycles:
1. The earth’s orbit changes from being nearly circular to slightly elliptical (eccentricity). This cycle is affected by other planets in the solar system and has a period of around 100,000 years.
2. The angle of tilt of the earth’s axis changes from 22.1° to 24.5° (obliquity). This cycle has a period of 41,000 years.
3. The direction of the tilt of the axis changes (precession) on a cycle of 26,000 years.
CO2 followed temperature change “with a lag of some hundreds of years” amplifies temperature change. Among other factors, CO2 is more soluble in colder than in warmer water. Higher dust levels are believed to be caused by cold, dry periods.