In his zeal to prove Global Warming is man made, an enthusiast dealt a crippling blow to some of the science that supposedly proves it’s man’s fault. He said science proves there was no global Medieval Warm Period. But there is ample proof of the Medieval Warm Period, so maybe what he proved is that "his" science isn't so good.
Why would he shoot down his own science?
He had to, he simply had no choice.
Why he attempted it is really simple. Global Warming caused by man’s creation of “greenhouse” gases must deal with both the Medieval Warm Period (800-1300) and the Little Ice Age (arguably 1500-1850). These were recent periods of rapid and large temperature fluctuations that don’t fit “it’s mankind’s fault” constructions. One way of dealing with the Medieval Warm Period and the Little Ice Age is to deny their existence, and find science that seems to support your denial.
Supposedly a 1,000 year Northern Hemisphere temperature reconstruction using data from multiple ice cores and tree ring records proves the Medieval Warm Period did not exist. Such proof of its nonexistence would justify its omission from Al Gore’s “hockey stick” graph of temperatures over the past 1,000 years. However, the scientists that reported that a global Medieval Warm Period did not exist conceded the existence of the Little Ice Age.
One question that seems to beg an answer is: "What caused the Little Ice Age?" If man is responsible for heating the planet now, what cooled it then?
This then leads to the next question. "What heated up the planet during previous warming periods?"
There were many. At least one following each of the four Ice Ages (actually glacial periods) of the past 400,000 years.
We're still in an Ice Age that began 40 million years ago, you know.
Major ice ages seem to be caused by many factors such as motion of tectonic plates, changes in Earth's orbit, solar variation, and changes in atmospheric gases concentrations, but probably not super-volcano eruptions and large meteorites, the effects of which dissipate quickly (in geological time, anyway).
Nature is responsible for vast changes in "greenhouse" gases because of the effects of solar energy. When sunlight strikes exposed rock, weathering occurs which absorbs atmospheric carbon dioxide and causes its decrease. This reduces the "greenhouse" effect, and the Earth becomes cooler. The cooler Earth becomes increasingly covered by ice and snow, reducing weathering of rocks and absorption of carbon dioxide. Then the "greenhouse" effect increases, temperatures rise, and snow and ice retreat.
Well, you know, the cycle repeats itself.
And repeats itself ...
A commonly accepted definition is that we're 10,000 years into an interglacial (warming) period, and some scientists think the next glacial period could start in 2,000 years. Some think it's not coming that soon, but most agree one is coming. It's just a matter of time before mankind will be freezing its tutus off again. And pining for good old Global Warming.
Less than thirty years ago the consensus of scientists (and Time Magazine) was we were on the verge of entering a disastrous period (for mankind) of Global Cooling.
"Quick, a show of hands! Global Warming, or Global Cooling? Who wants Global Cooling?"
"Only One? I'm shocked. We usually have at least two snow boarding nuts in the crowd."
If you think Global Warming would be bad, think about what Global Cooling will do.
We'll starve. Harvests will be terrible. Northern wheat fields will be frozen tundra. Only hardy crops will grow in Florida. Florida orange juice will be from Ecuador. Port cities will become former port cities as ice caps grow and oceans retreat. The Sacramento River will run under the Golden Gate Bridge, and enter the Pacific on its west side. Thousands of nuclear plants built on the sites of useless solar and wind farms will be the primary source of power for heating homes, powering industry, and growing crops in vast "greenhouses."
Millions of years ago major glacial periods occurred every 40,000 years, but more recently every 100,000 years. What happened between glacial periods? The Earth warmed, the ice caps retreated, and mankind still huddled around fires at night for warmth and protection against wild animal attacks.
One very plausible answer to what caused the Little Ice Age is solar variation, as measured by sunspot activity. The Little Ice Age corresponds with periods of low solar activity called the Spörer and Maunder Minimums. Warmer weather since seems to match the increased solar activity observed in the past hundred years. It would be odd indeed if reduced solar activity caused the Little Ice Age, and increased solar activity didn’t play a part in ending it. Or that solar variation did not play a significant part in prior cold and warm periods.
In fact, it doesn’t seem logical that the activity of our Sun, the agent of heating our planet and driving our weather, wasn’t responsible for the vast cycles of previous hot and cold periods.
This brings us to the "scientifically" proven non-existence of a global Medieval Warm Period. Do we have any proof of a Medieval Warm Period? And if that proof is convincing, doesn’t it weaken the science that underlies the proof presented by the doubters?
For proof of a Medieval Warm Period, let’s start with something mankind has been keenly interested in for a long time. Besides womankind, that is. What could it be? Spiritus fermenti, of course, and in particular, wine. During the time of the Norman Conquest (1088), vines were grown and wine was made at many monasteries in southern England, and viticulture continued through the time of King Henry VIII (1491-1547). Then the vineyards declined and disappeared.
Did the English lose interest in wine? When Henry VIII closed the monasteries, did the lack of monks lead to a loss of interest in wine? Were monks the Party Hearty Bunch of the Middle Ages?
Or is it more likely that the colder climate leading into and through the Little Ice Age made it difficult to grow vineyards in England? As evidence that bad weather was the probable cause, English imports of wine from France increased. English interest in wine hadn’t waned, but the grape-growing ability of the English climate had.
Now that English weather is warming again, vineyards have reappeared since approximately 1950 without benefit of monks or monasteries. However, even with modern science to develop grapes suited to English weather, soil conditions, and other advances in viticulture unknown to the ancients, wine production in England is an iffy proposition. Some say cruelly that the best way to get a small fortune is to have a large fortune and buy an English vineyard. Clearly, vineyards in England, even with modern advances and scientific progress, still haven’t gotten English wine production back to the levels achieved during the Medieval Warm Period.
One of the criticisms of the Medieval Warm Period is that it possibly wasn’t global. Is there evidence that it occurred in more places than England? The answer is yes, and instead of grapes, the test subjects used were humans, collectively known as Vikings, to demonstrate its existence. During the years 800-1200, Iceland and Greenland were settled by the Vikings.
Animal bones and other materials collected from archaeological sites reveal Icelandic Vikings had large farmsteads with dairy cattle (a source of meat), pigs, and sheep and goats (for wool, hair, milk, and meat.) Farmsteads also had ample pastures and fields of barley used for the making of beer and these farms were located near bird cliffs (providing meat, eggs, and eiderdown) and inshore fishing grounds. Fishing was primarily done with hand lines or from small boats that did not venture across the horizon.
The Greenland Vikings lived mostly on dairy produce and meat, primarily from cows. The vegetable diet of Greenlanders included berries, edible grasses, and seaweed, but these were inadequate even during the best harvests
However, Greenland was more hospitable then for habitation than now.
In the case of the Vikings, there was no equivalent of a Henry VIII to allow equivocation about the reason for failure of the Viking Iceland and Greenland colonies. Archeology confirms that the Iceland and Greenland colonists suffered increasingly from malnutrition as colder weather diminished crops, and drove schools of cod to better feeding grounds further south. The Vikings became shorter, and as conditions worsened, the Greenland Vikings became severely crippled, dwarflike, twisted, and diseased. By 1492, Greenland was “dead.”
The population of Iceland fell from a high of 77,500 in 1095, to only 38,000 in the 1780’s, and the average Icelander was two inches shorter than the earlier settlers.
Now we've entered another period of warming, only this time we have scientists playing Chicken Little. Thirty years ago they were all over Global Cooling. Now they're all over Global Warming. It's gotten so bad now that each hurricane, every record temperature, an El Niño or La Niña, is looked on as a portent of Global Warming.
As long as it supports the prophecy du jour, that is.
Our scientists are taking us back to the good old days of Greek mythology, when the Oracles of Delphi were consulted, and priests devined the future by sniffing vapors, and reading the entrails of animal and human sacrifices.
Now they consult tree rings and ice cores, and declare that scientific evidence proves accepted historical events never occurred.
From the perspective of the sacrificial victims, at least some progress has been made.
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