Among the issues most commonly discussed are individuality, the rights of the individual, the limits of legitimate government, morality, history, economics, government policy, science, business, education, health care, energy, and man-made global warming evaluations. My posts are aimed at intelligent and rational individuals, whose comments are very welcome.

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Showing posts with label Roman Warming. Show all posts
Showing posts with label Roman Warming. Show all posts

27 June 2012

Was the Warming of the Late 20th Century Unprecedented?

Those who claim that the effects of man's emissions of carbon dioxide on climate are catastrophic, have commonly said the high temperatures of the late 20th Century and the rate of their rise was unprecedented.  All of the extensive evidence of warm periods in Europe and around its periphery is often said to be only due to local effects, without a worldwide analog.  Over the last 10 years more evidence that these warm events existed in places such as China and South America has been found, but the non-European evidence is not so voluminous that those who make the claim of unprecedented warming recently have been quieted.  A new study of sea surface temperatures in the East China Sea over the last 2700 years adds to that evidence that the recent history has precedents.


Weichao Wu of Peking University and 4 other colleagues of various universities in China collected a sediment core from the sea floor in the Southern Okinawa Trough over which the warm Kuroshio current flows.  "The researchers analyzed the top 10 meters of the sediment core, corresponding to 2,700 years of sedimentation and from it were able to resolve 25-yr averages. To determine the SST, they used the “relative number of cyclopentane isoprenoid GDGTs in marine crenarchaeota (Thaumarchaeota)” which “increases with increasing growth temperature.”""  "...they identified a tracer in the sediment layers that is a measure of the relative abundance of a tiny marine organism whose number is sensitive to the sea surface temperature. The more crenarchaeota that are evident in the sediment layer, the higher the ocean temperature."

The temperature history from this proxy reconstruction is shown in the graph below with data points for each 25-year average and a running three-point mean line. 



Their sea surface temperature reconstruction clearly shows the Roman Warm period (RWP), the Dark Age Cool Period (DACP),  the Sui-Tang dynasty Warm Period (STWP),  the Medieval Warm Period (MWP), the Little Ice Age (LIA), and the Current Warm Period (CWP). The warm period from 500 to 350 BC was when Persian and Greek civilizations arose.  The highest temperature data point for this period is higher than any for the recent CWP.  The rate of rise at its start is also faster.  The highest temperature in the RWP is also higher, as is the rate of initial rise in temperature for the RWP, compared to the CWP.  The STWP seems to have displaced a longer Dark Ages Cool Period in Europe.  The highest temperature in the MWP in the East China Sea is higher than the recent warming also, though the MWP in Europe was more substantial than that in the East China Sea.

The important thing is that higher temperatures and higher rates of temperature increase, as well as higher rates of temperature decrease, have occurred in the past in other areas of the world with a significant correlation to the events of Europe and its surroundings.  The temperature proxy data used to construct the hockey stick temperature record of the last IPCC assessment report was very limited.  As pointed out by Ian Plimer in Heaven and Earth global warming the missing science, there actually is much information from around the world that indicates how misleading that hockey stick temperature plot really was.

16 August 2009

Medieval Warming to Little Ice Age

If the warming of the late 20th Century had not come to an end, what kind of catastrophe were we headed for? Apparently one similar to the Medieval and Roman Warmings. Well, what does Ian Plimer in his wonderful book Heaven and Earth have to say about that?

The Medieval Warming period from 900 to 1300 was a period of great human advances in Europe, China, and Angkor Wat in southeast Asia. Humans generally prospered and were able to more easily feed and cloth themselves. As a result, they had enough time and resources to be able to undertake the building of cities, great cathedrals, and the start of universities throughout Europe. Europe started importing goods from China and the East Indies via the Orient. The Orient itself prospered with renewed agriculture, trade, and the establishment of institutions of learning. This period was warmer than the late 20th Century period.

The Medieval Warming was not nearly as warm as had been the longer Holocene Climate Optimum from 7000 BC to 3000 BC, but it was about the equivalent of the Roman Warming between 250 BC and 450 AD. Europe was warm, rainfall was plentiful, the climate was stable, and agricultural production became more bountiful and reliable. Farmers were able to farm to higher elevations in the mountains. Food production increased enough to allow the population to increase from 30 to 80 million in Europe. The population of China doubled in 100 years also.

There was a great expansion in trade. People could produce more than was needed for subsistence and were able to trade the excess. The warm period was accompanied by fewer storms and intense winds were less common than during the Dark Ages. Note that this is contrary to the claims of many Global Warming Alarmists today. Coastal trade and long distance ocean trade routes were widely established. Movement overland became easier. Though it rained more, there was also more sunshine to dry out the mud on roads. Mountain passes were open for longer periods.

The Vikings settled in Iceland, Greenland, and in North America. They farmed barley and raised cattle and sheep in Greenland. They had vineyards in Newfoundland. They fished for cod and hunted seals in ice-free waters. The Vikings traded extensively in Russia and Kievan Rus, down to Persia and Constantinople.

The Doomsday Book shows grapes were grown in England where they cannot be now. England was warmer and drier then than it is now. Its population grew from1.4 million to 5.5 million. the population of France tripled to become 18 million. Vineyards in Germany went to altitudes of 780 meters, though they only go to 560 meters now. This implies the average temperature was about 1.0 to 1.4 degrees C higher than now. In Norway, the land was cleared, settled, and farmed about 100 to 200 meters higher in elevation than now, suggesting a temperature average about 1 degree C higher than now. In 1000 AD, the treeline of the polar Urals was higher than it is now.

Mining in the higher Alps occurred both in the Roman and Medieval Warming periods. These mines were covered with ice in the Dark Ages and again in the Little Ice Age. Some of these mines were again exposed with the ice retreat of the late 20th Century warming. The sediments of Lake Neufchatel in Switzerland show it was warmer in the Medieval Warming than now, but that a 1.5 degree C temperature drop occurred quickly with the start of the Little Ice Age. The Baltic Sea supported tropical and sub-tropical plankton then, but cannot do so now.

A study of 600 boreholes on all continents shows that the Medieval Warming period was warmer than today. They also show a drop of 0.2 to 0.7 degrees C due to the Little Ice Age. Turkey, Northern Africa, Pakistan, southern Africa, Japan, the Great Plains of North America, Alaska, northern Quebec, southern Ontario, the Sierra Nevada Mountains, Mono Lake in California, the Anasazi Indian area, southern Alberta, Argentina, Peru and the Andes, and the South Pacific all experienced the Medieval Warming with benefits to the people of the regions. Similarly, when the Little Ice Age was experienced in all these areas, the people suffered.

Of course, these temperature changes were not caused by CO2 emissions by man. They were caused by changes in the irradiance of the Sun, changes in its magnetic fields, and in its emissions of solar wind and the resulting interactions with cosmic rays.

So, if the 20th Century warming had continued, mankind might have enjoyed the many benefits enjoyed by human civilizations in the Roman and the Medieval Warmings. Those benefits are the catastrophe the Democrats and the rabid environmentalists are trying to protect us from by bringing on catastrophic energy use restrictions and taxes. Had they simply done their homework and taken some reasonable regard for the great wealth that the Industrial Revolution has brought to mankind in increased security, longer lives, a richer intellectual life, and so much more, they would not be intent upon throwing wrenches and bolts into the gears of our economy. In the name of a phantom global warming catastrophe caused by human use of fossil fuels, they would throw many of us out of jobs, leave us in chilled homes and businesses in the winter, in swelteringly humid buildings in summers in which electronics cannot long function, deprive our businesses of profits, and restrict our travel.

As is so often the case, wrong-headed Democrats are coming close to destroying the miracle of America. Perhaps the coming Great Chill caused by our Sun will keep them from wrecking destruction via the route of energy use restrictions. Of course, the Great Chill will itself make life harder, as such chills always have. And, of course, the Democrats are always, without pause, looking for more ways to inhibit our pursuit of happiness as humans. They are especially fond of finding ways to reduce our production of the goods and services that people want.