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Every so often, Earth's magnetic field flips on its head, turning the magnetic North Pole into the South Pole and vice versa.
It last happened 780,000 years ago, and is predicted to occur again in about 1,500 years ... maybe.
The overall frequency is hard to predict — there was one period in Earth's history when the field didn't reverse for 30 million years.
Why these flip-flops happen at all is a great riddle, but a new hypothesis on the origins of the magnetic field could shed light on the reason.
Originally posted by vegno
Talk about giving the alarmist a run for their money. Yes, it is conveniently called "Climate Change" now. Right, that still means CO2 is deadly, let's tax breathing, carbon credit scam and all that good stuff.
As always, keep up the good work redneck, you never fail to impress.
This paper presents a review of the time period A.D. 1400-1980 based on Greenland ice cores from the central west Greenland averaged record, and from winter and summer seasonal isotopic records from the Greenland Ice Sheet Project 2 (GISP2). This time period includes the so-called "Little Ice Age". The concept of the "Little Ice Age" has evolved from the idea of a simple, centuries-long period of lower temperatures to a more complex view of temporal and spatial climatic variability. In the central Greenland ice core isotopic signals, the fifteenth and early sixteenth centuries show multi-decadal excursions above and below the mean reference. The sixteenth and mid-eighteenth to mid-nineteenth centuries are notable for decade-to-decade swings (high-low) in the isotopic signal, while multi-decadal low excursions dominate the seventeenth century. The "subdued" nature of the "Little Ice Age" isotopic signal in central Greenland is probably influenced by the North Atlantic Oscillation (NAO), which presents opposing temperature excursions between west Greenland and northern Europe. Changes in the prevailing atmospheric circulation (Iceland Low) can explain some of the spatial and temporal variability between the central Greenland isotopic records and Iceland temperature.
Sea ice was a key factor in the development of the Viking immigration into Greenland and the ultimate demise of their settlements. The Vikings sailed from Iceland and first settled in Greenland in 981. They developed pasture land and farms on the western Greenland coast. However, in the harsh environment, they were not self-sufficient and required supplies, which were transported from Norway and Iceland across the sea. This was a relatively warm period of history, and sea ice was uncommon in the trade route between Greenland and Europe. By the 1300s, the climate had turned much colder.
Trade decreased with Norway, partly because of political and economic factors in Norway, but also because of the increasing sea ice, which made transoceanic travel more costly and dangerous. After the early 1400s, contact was completely lost with the Greenland Vikings. When the next European ship sailed into the region almost 150 years later, the sailors encountered no surviving settlers. While the colder temperatures affected the Vikings primarily through lower crop yields and a stressed food supply, increased sea ice likely had some effect by cutting off the delivery of necessary supplies from mainland Europe.
Originally posted by TheRedneck
OK, I know which page you meant. But rather than just post a page with a definition of precipitation, how about telling me what you disagree with in my post? I think that would more aid the debate than just typing in a link to try and say I don't know what I am talking about.
I agree that warmer air is capable of holding more moisture than cold air. That's simple physics. My only point is that the possible moisture content is not the only force that affects precipitation, and compared to the other variables that affect precipitation amounts, a 3°C temperature rise is minor. Do you disagree with that? If so, what are the physics upon which you base this disagreement?
Less Ice In Arctic Ocean 6000-7000 Years Ago.
Recent mapping of a number of raised beach ridges on the north coast of Greenland suggests that the ice cover in the Arctic Ocean was greatly reduced some 6000-7000 years ago. The Arctic Ocean may have been periodically ice free.
”The climate in the northern regions has never been milder since the last Ice Age than it was about 6000-7000 years ago. We still don’t know whether the Arctic Ocean was completely ice free, but there was more open water in the area north of Greenland than there is today,” says Astrid Lyså, a geologist and researcher at the Geological Survey of Norway (NGU).