When Eric the Red led Norse families to settle on Greenland at the end of the tenth century, he had no idea that he and his descendants were about to demonstrate dramatically the Earth's long, moderate climate cycle.
Sailing their longships west from Iceland in circa 985, the Vikings had been pleased to find a huge new uninhabited island, its shores covered with green grass for their cattle and sheep, surrounded by ice-free waters where codfish and seals abounded. They could grow vegetables for their families and hay to feed their animals through the winter. There was no timber but they could ship dried fish, sealskins and tough rope made from walrus hideto other Norse ports to trade for what they needed. The colony thrived, growing by the year 1000 to three thousand people with twelve churches and its own bishop. The inital settlement split into two: one on the southwestern coast and one further north also on the west coast.
The Vikings did not realize that were benefiting from the Medieval Warming, a major climate shift that lasted approximately four hundred years that made Northern Europe about 2°C warmer that it had been privously. Nor did they realize that after the warming ended, their grassy domain was doomed to five hundred years "the Little Ice Age" of ice temperatures unmoderately by the Gulf Stream that warmed the Norse settlements in Norway and Iceland.
As the Little Ice Age progressed, the colonists were increasely hard pressed to survive. The pack ice moved closer to Greenland. Supply ships had to take a more southernly route to avoid the deadly ice. Less hay could be harvested in shorter, cooler summers to feed the livestock through longer and colder winters. The storms got worse by 1350, glaciers had crushed the northern Greenland settlement. The last supply ship got through to the southern settlements in 1410; then they were cut off.
There was fighting with Inuit hunters as they pushed south by enrouching ice to compete with Norse for the seals. The cod followed the warm water south, away from the colonies. Skeletons in the settlements' graveyards show the people growing shorter, indicating poor nutrition.
We do not know whether the last colonists died at the hands of the Inuit or starved to death, or even just when
they died. We do know they had eaten the last of their milk cows. Measuring the change in oxygen isotopes of
Greenland Norse Skeletons' tooth enamel indicates a 1.5°C drop in average temperatures between the years of 1100 and 1400.
Denmark would not recolonize Greenland until 1721, when the Little Ice Age was loosing its grip on the huge island. Today 150 years into the Modern Warming, Greenland has 50,000 people and 20,000 sheep. Most of the people earn their living by catch shrimp and fish, though there is a short summer season for hardy tourists. The ruins of Norse cathedral and the bishop's palace have been partially restored as a memorial to Greenland's Norse era.
Greenland is likely to become even more popular as a tourist attraction for as long as the Modern Warming last, probably at least serveral hundred more years. But ice cores and seabed sediments tel us of six hundred natural 1,500-year cycles over the past one million years. The cycle will eventually shift again and Greenland will descend into ice and hardship.
the only significant difference between the 15th centur's Little Ice age and the next is likely to be human technology available to cope with it.The 25th century's Greenlanders will have better insulation and bigger, safer fishing vessels than did their ancestors, plus satalite communications and powerful, ice-breaking supply ships.
Change in Oxygen-18 Ratio in
Greenland Ice Cores, A.D. 820-1985
The changing concentration
of oxygen-18 in Greenland
ice cores corresponds to the
1,500-year cycle.
More Information
During the Medieval Warming of 950-1300,
the Britons themselves grew wine grapes in England. The Domesday Book,
compiled in the 11th century, recorded 46 places in southern England growing
wine grapes. (Richard Tkachuck of the Geosciences Research Institute notes
that German vineyards were found as high as 780 meters in elevation during
the Medieval Warming, but are found today up to only 560 meters — indicat-
ing a temperature difference of 1° to 1.4° C.2)
During the Little Ice Age (1300-
1850), England was too cold to grow wine grapes. Instead, London often held
ice festivals on the frozen Thames River, which hasn’t frozen in the last 150
years.
Now that the Little Ice Age has given way to the Modern Warming, a
few hardy Britons have again begun serious efforts to grow good wine grapes
in England — but thus far with spotty success. The Web site www.english-
wine.com admits that British wine-making is still a very chancy proposition.
Only two years in 10 will the wine be very good, and during four of the other
years it will be terrible, “largely due to weather....”
British vintners should be hopeful, however. The Modern Warming is
still young, and likely to eventually give them several centuries of good wine
production. The Earth is apparently having its third natural, moderate — and
unstoppable — warming in 2,000 years.
Taken by itself, the cycle of wine-grape growing in England might be
seen as an aberration. However, this is just one bit of the emerging body of
physical evidence of a natural climate cycle — a cycle too moderate and too
long to have been reported in the Viking sagas and earlier oral histories from
people without thermometers.
Figure I tracks the Medieval Warming and Little Ice Age that preceded
today’s Modern Warming.
We have long had physical evidence that the Earth has experienced
numerous climate cycles throughout its history. The best-known of these is
the Ice Age cycle, with 90,000-year Ice Ages interspersed with far shorter
interglacial periods. What is new is the evidence of more moderate, persistent
climate cycles within these broader cycles.
The Earth's climate cycles through 90,000-year Ice Ages interspersed with shorter warm periods.
Within the longer cycle, the climate warms and cools in 1,500 year-cycles (plus or minus 500years).
Evidence from every continent and ocean confirms the 1,500-year cycle.
The Physical Evidence of Earth’ s Unstoppable 1,500-Year Climate Control 3
None of these pieces of evidence would be convincing in and of them-
selves. However, in order to dismiss the huge impact of the 1500-year climate
cycle, we would have to dismiss not only the human histories from those pe-
riods, but also the enormous range and variety of physical evidence presented
here.
Importantly, if the current warming trend is, as the evidence suggests,
part of an entirely natural climate cycle, actions proposed to prevent further
warming would be futile and could, by imposing substantial costs upon the
global economy, lessen the ability of people to adapt to the impacts — both
positive and negative — of climate change.
The National Center for Policy Analysis
up 250,000 years of the Earth’s frozen, layered climate history. Over the
previous dozen years, the two researchers had pioneered ways to pry information from the ice cores. They had learned, among other things, that the ratio of
oxygen-18 isotopes to oxygen-16 isotopes in ice could reveal the air tempera-
ture at the time when the snowflakes that made the ice fell to earth. The corre-
spondence of the change in the isotope ratios to the recent Medieval Warming
Period (MWP) and Little Ice Age (LIA) is shown in Figure II
Dansgaard and Oeschger expected to see the big 90,000-year Ice Ages
in the cores, and they did. But they were startled to find, superimposed on the
big Ice Age swings, a smaller, moderate and more persistent temperature cycle.
They estimated the average cycle length at 2,550 years. They dismissed volca-
noes as a causal factor because there’s no such cycle in volcanic activity. The
timing of the cycles seemed to match closely with the known history of recent
glacier advances and retreats in northern Europe.
The report that Dansgaard and Oeschger wrote in 1984, “North Atlantic
Climatic Oscillations Revealed by Deep Greenland Ice Cores,” was, in retro-
spect, almost eerie in its accuracy, its completeness and its logical linking of
the climate cycles to the sun.4 The only major correction imposed by subse-
quent research is that the cycles were more frequent than they thought. The
average length of the cycles has now been shortened by almost half — from
their original estimate of 2,550 years to 1,500 years (plus or minus 500 years).
Dansgaard and Oeschger were correct when they told us that the
climate shifts were moderate, rising and falling over a range of about 4° C in
northern Greenland, with very little temperature change at the equator — and
only half a degree when averaged over the northern hemisphere.
The cycles were confirmed by 1, their appearance in two different ice
cores drilled more than 1,000 miles apart; 2 their correlation with known
glacier advances and retreats in northern Europe; and 3, independent data in a
seabed sediment core from the Atlantic Ocean west of Ireland.
They noted that the cycle shifts were abrupt, sometimes gaining half of
their eventual temperature change in a decade or so. That suggested an exter-
nal forcing, perhaps amplified and transmitted globally by the ocean currents
and winds. (In the mid-19th century, the Upper Fremont Glacier in Wyoming
went from Little Ice Age to Modern Warming in about 10 years.6 That implies
a climate driver from outside our planet, almost certainly involving the sun.)
Since the solar radiation is
the only important input of energy to the climatic system, it is most obvious
to seek an explanation in solar processes. Unfortunately we know much less
about the solar radiation output than about the emission of solar particulate
matter in the past.
The two scientists did know, however, that both carbon-14 and beryl-
lium-10 isotopes vary inversely with the strength of the solar activator. The
Ice cores from Antarctica show the same climate
cycle.
The Physical Evidence of Earth’s Unstoppable 1,500-Year Climate Control 5
isotopes of both elements in their Greenland ice cores showed historic tem-
perature lows during what solar scientists term the Maunder sunspot minimum (1645–1715) — the absolute coldest point of the Little Ice Age and a period when sunspots virtually disappeared.
