With all the hoopla regarding global warming one salient fact is forgotten. We are living in what is an unusual period in earth's history. For the better part of the last million years, the earth has been in what we call an ice age. These ice ages are seperated by short interglacial periods. We are in such a period now. Were another ice age to hit, it could mean the end of civilization as we know it. The last "little ice age" to hit was in the middle ages and was a time of famine and death capped off by the black death which killed 1/3 of the human race. Why has this interglacial period lasted so long? Is it possible that anthropogenic effects have staved off an ice age? More importantly, is it possible that attempts to cool the earth could be all too effective and kick off another ice age that could all but wipe out civilization? For ninety percent of the last million years, the normal state of the Earth's climate has been an ice age. Ice ages last about 100,000 years, and are punctuated by short periods of warm climate, or interglacials. The last ice age started about 114,000 years ago. It began instantaneously. For a hundred-thousand years, temperatures fell and sheets of ice a mile thick grew to envelop much of North America, Europe and Asia. The ice age ended nearly as abruptly as it began. Between about 12,000 and 10,000 years ago, the temperature in Greenland rose more than 50 °F. We don't know what causes ice ages to begin or end. In 1875, a janitor turned geologist, James Croll, proposed that small variations in Earth's orbit around the Sun were responsible for climate change. This idea enjoyed its greatest heyday during the 1970s, when ocean sediment cores appeared to confirm the theory. But in 1992, Ike Winograd and his colleagues at the US Geological Survey falsified the theory by demonstrating that its predictions were inconsistent with new, high-quality data. The climate of the ice ages is documented in the ice layers of Greenland and Antarctica. We have cored these layers, extracted them, and studied them in the laboratory. Not only were ice ages colder than today, but the climates were considerably more variable. Compared to the norm of the last million years, our climate is remarkably warm, stable and benign. During the last ice age in Greenland abrupt climatic swings of 30 °F were common. Since the ice age ended, variations of 3 °F are uncommon. For thousands of years, people have learned from experience that cold temperatures are detrimental for human welfare and warm temperatures are beneficial. From about 1300 to 1800 AD, the climate cooled slightly during a period known as the Little Ice Age. In Greenland, the temperature fell by about 4 °F. Although trivial, compared to an ice age cooling of 50 °F, this was nevertheless sufficient to wipe out the Viking colony there. In northern Europe, the Little Ice Age kicked off with the Great Famine of 1315. Crops failed due to cold temperatures and incessant rain. Desperate and starving, parents ate their children, and people dug up corpses from graves for food. In jails, inmates instantly set upon new prisoners and ate them alive. The Great Famine was followed by the Black Death, the greatest disaster ever to hit the human race. One-third of the human race died; terror and anarchy prevailed. Human civilization as we know it is only possible in a warm interglacial climate. Short of a catastrophic asteroid impact, the greatest threat to the human race is the onset of another ice age. The oscillation between ice ages and interglacial periods is the dominant feature of Earth's climate for the last million years. But the computer models that predict significant global warming from carbon dioxide cannot reproduce these temperature changes. This failure to reproduce the most significant aspect of terrestrial climate reveals an incomplete understanding of the climate system, if not a nearly complete ignorance. Global warming predictions by meteorologists are based on speculative, untested, and poorly constrained computer models. But our knowledge of ice ages is based on a wide variety of reliable data, including cores from the Greenland and Antarctic ice sheets. In this case, it would be perspicacious to listen to the geologists, not the meteorologists. By reducing our production of carbon dioxide, we risk hastening the advent of the next ice age. Even more foolhardy and dangerous is the Obama administration's announcement that they may try to cool the planet through geoengineering. Such a move in the middle of a cooling trend could provoke the irreversible onset of an ice age. It is not hyperbole to state that such a climatic change would mean the end of human civilization as we know it. Earth's climate is controlled by the Sun. In comparison, every other factor is trivial. The coldest part of the Little Ice Age during the latter half of the seventeenth century was marked by the nearly complete absence of sunspots. And the Sun now appears to be entering a new period of quiescence. August of 2008 was the first month since the year 1913 that no sunspots were observed. As I write, the sun remains quiet. We are in a cooling trend. The areal extent of global sea ice is above the twenty-year mean. We have heard much of the dangers of global warming due to carbon dioxide. But the potential danger of any potential anthropogenic warming is trivial compared to the risk of entering a new ice age. Public policy decisions should be based on a realistic appraisal that takes both climate scenarios into consideration. David Deming is a geophysicist and associate professor of Arts and Sciences at the University of Oklahoma. American Thinker
I'll see if I can track it down, however I recall coming across an article that essentially suggested that if we modulated our burning of fossil fuels in just the right way, we could stave off the next ice age for a few hund\red thousand years (I think 500k was the figure I saw).
If we try really hard, we can do both - bring down a fantastic heat wave faster than any climate change since the last asteroid impact, and then fall off of a temperature cliff into the next ice age faster than ever before. Interesting times. (The plague, btw, hit the large populations of Asia before it hit Europe - and has been suggested as a cause, rather than a consequence, of the cold climate, in its effects on CO2 and methane production from Asian agriculture. )
Dumb question but I'll ask anyway. There are scientists who claim there is evidence of the tree line moving north. I think one of the good things associated with the end of an ice age is the recapturing of the land by vegetation. With the ice gone can you see a period where vegetation will totally encompass once barren lands and if so, then will this have a positive effect on reducing greenhouse gas levels?
First, ice ages don't "hit." As you can see by this graph, they arrive gradually, over a 5,000 to 20,000 year period. Second, ice ages involve only a 5 deg C drop in temps - we experience a greater drop when the sun is obscured by clouds. The Black Death (circa 1350) preceded the Little Ice Age , which began around 1650, by 300 years. Your association of the two events is in error. No. Effective? No. At best, trillions and trillions of dollars may reduce global warming by 10%. The remaining 90% will march right along. Absolutely not. We're a *bit* more hardy a species than you might think! We've weathered a dozen ice ages. Yes. That is absolutely false. Somewhat true. Ice ages tend to take about 10,000 years to develop, but they tend to end over a thousand year period or so. The Little Ice Age began in 1650. You're more than 300 years off-target. You're correct, and it's because CO2 levels weren't the cause of the LIA. Your statement only reveals that you're attempting to extrapolate greenhouse gas climate model to explain a non-greenhouse gas climate change, and are failing. Perhaps that's because meteorologists are trained to predict the weather, while climatologists are trained to predict the climate. Please Register or Log in to view the hidden image!
You should be comfortable with a move to a Pacific atoll then, and waiting things out for 20 years. I hear land is going for a real song in the Maldives.
Oh, those silly Brits: LONDON - Over 1700 scientists in Britain have signed a statement defending the evidence for human-made climate change in the wake of hacked e-mails that emboldened climate skeptics.
I have heard that we are in an interglacial period of an ice age. It appears that no one truely knows why they start and stop. Perhaps it has been solved and has nothing to do with Milankovitch. Perhaps we will wake up and find that Greenland has fallen in temperature by 50 degrees and global warming is a "red herring". At least herring have substance. "He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people, and eat out their substance. Thomas Jefferson in the Declaration of Independence in reference to King George III.
