World Climate Past and Present-JLB

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Non-experts opinion on Climate Change
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  World Climate Recent Past and Present  Kanook – Oct, 2009 Records available show that from the end of the Optimum Period 1 of sustained warmth until around 800-900 AD the climate of the world,particularly in Europe varied between periods of warmth and cold. Thisevidence, found on the height of the upper tree lines (where it shows thattrees grew to a higher altitude) following the perk warm period around 5000BC, show a steady decline lasting up into the 20 th century. Tree ring data forNew Zealand, for example, indicate that after temperatures reached amaximum around 6000 to 8000 BC, the climate of New Zealand cooled.Beginning around 1000 BC the climate of Europe and the Mediterraneancooled dramatically and by 500 BC had reached today’s temperatures,whereas from 500 BC to 600 AD 2 it experienced periods of varied warmth,although much cooler on average than the previous 4,500 years with the overclimate becoming somewhat more stable from 100 BC to 400 AD, the period of the rise of the Roman Empire.During this period the Italians had vineyards and olive trees farther norththan before, classical Greece flourished and then declined; the Roman Empirespread its authority through much of what is now Europe, the Middle East, andNorth Africa only to be overrun by the hordes from Central Asia as their wealthincreased and they looked eastward to expand into other territories. Whetheror not climate change drove them east is still up to debate.Evidence points to the migration of people from the northern latitudes duringthe cooling period, along with the Greeks adopting warmer clothes after 1300BC 3 and the population base in the Alps decreased. As the cooler weatherprevailed Greece and Turkey experience prolonged periods of droughtbetween 1200 to 750 BC, brought on by the cooling weather patternsdecreasing the evaporation of the seas, hence much less rainfall. The drop in temperature is also supported by the evidence found that theharbors of Naples and other ports in the Adriatic being three feet below thecurrent water levels, this backed by the lowering of water levels on the NorthAfrican coast and around the Aegean, the Crimea, and the easternMediterranean in the Levant. Lower water levels indicate a colder climateleading to the buildup of snow and ice at the poles and in major mountainglaciers, but, by 400 AD temperatures has warmed enough to raise waterlevels to at least three feet above current levels. A good example of this is 1 1 Holocene Climate Optimum was a warm period during roughly the interval 9,000 to 5,000years B.P. 2   Medieval Warm Period was a time of warm weather around AD 800-1300 3 Beginning around 1850, the climate began warming and the Little Ice Age ended  some ancient harbors in Rome and Ravenna now sit about 1 kilometer fromthe sea, there is also world evidence of the peak ocean heights found in Brazil,Ceylon, Crete, England, and the Netherlands, indicating a worldwide warmingperiod.Near the end of the Roman Empire, around 300 AD, the climate began towarm and the conditions in Central Asia improved apparently leading to apopulation explosion, and the people needed room to expand and a way tosurvive, consequently when a civilization wants to expand for whatever reasonthey search out new lands and cultures to expand into, the Mongolians took itupon themselves to move south and west invading China and parts of Europe.During the 2 nd Optimum Period, the homeland of the Khazars 4 centeredaround the Caspian Sea experienced heavy rainfall as compared to theirearlier history which increased prosperity in the region producing a highincrease in young men, men that provided the manpower for Genghis Khan toinvade China and India and to terrorize Russia and the Middle East,After 500 AD until around 800 AD, Europe went through a colder, wetter, andincreased stormy weather and as the moisture increased peat bogs formed innorthern areas, and the people abandoned many lakeside dwellings whilemountain passes once again became choked with ice and snow, closing down,or making more difficult to use, the transportation routes between NorthernEurope and points south. Parts of the Mediterranean and Northern Africa driedup, although they remained much wetter than they are today.Medically the people of England through the 7 th and the 9 th centuries wereoften crippled with arthritis, whereas during the previous warmer Bronze Age 5  the incidence of arthritis was almost non-existent. During the centuries afterthe “Fall of the Roman Empire”, the Greek’s suffered with a diminishedeconomy and were overwhelmed with sickness aggravated by cold, dampconditions; on top of this the “Black Death” roamed the land between 744 ADand 747 AD taking overwhelming victims during its leisurely stroll across thecountryside. In the aftermath, during the 9 th and 10 th centuries when theByzantine Emperors hauled the Greek settlers back from Asia Minor back tothe sea, for the 1 st time Greek commerce and its prosperity returned as theclimate improved.From 800 – 900 AD, the Vikings raided with furry outside their borders of Scandinavia, there are three theories on what they left their shores and usingtheir superior naval technologies expanded their realm as far west as theAmericas and south into Africa. One theory is that they had outgrown theiragricultural potential, a theory that doesn’t quite hold up in that if this was thecase why not move east into the large tracks of land, the 2 nd theory was theywere well aware of the internal divisions in the surrounding regions, for 4 The Khazars were a semi-nomadic Turkic people who dominated the Pontic steppe and theNorth Caucasus from the 7th to the 10th century CE. The name 'Khazar'   seems to be tied to a Turkic verb form meaning wandering 5   Bronze Age (3300–1200 BC)  example the Danish Vikings of the divisions in Charlemagne’s Empire, and lackof organized naval opposition allowed them to range throughout many townsand navigable rivers traveling freely and raiding or trading at will. Lack of legitimate trade after the Fall of the Roman Empire and the expansion of  Islam in the 7 th century had affected the profitability of their old trade routes.Whatever their reason, they accomplished their expansion in some prettymoderate weather, at one time setting up camp in Greenland where thefarming was great and the game plentiful – they named the island,“Greenland” later travelers name “Iceland”.From around 800 AD to 1300 AD the world warmed considerably andcivilization prospered. The period is labeled the “ Little Climate Optimum / Medieval Warmth and in general mimics the first Climate Optimum wherevirtually all of Northern Europe, Britain, Ireland, Greenland and Iceland wereconsiderably warmer than at present. The Mediterranean, the Near East, theArabian peninsula and North Africa including the Sahara experienced morerainfall than today, and even North America enjoyed much better weather –from Western Europe to China, East Asia, India and the Americas, mankindflourished as never before.Although the European continent received more rainfall, the western UnitedStates, especially in eastern California and the western Great Basin 6  experience prolonged droughts and Alaska experience three time intervals of comparable warmth, (1-300 AD), (850 to 1200 AD) and post 1800 AD). Treerings from the upper tree lines in Europe, and from several sea levels indicatea more benign, warmer climate withmore rainfall; and because of evaporation, less standing water.Not only did Northern Europe enjoymore rainfall the Mediterraneanclimate was much wetter, whereasan early 12 th century bridge that stillexists over the river Oreto atPalermo exceeds the needs of thesmall trickle of water that flowsbeneath it today. In addition, twoArab geographers note that two rivers in Sicily that are two small for boatstoday were navigable during this period and in England medieval water millson streams today do not carry enough water to turn the wheels. Rain; therewas plenty during the Little Climate Optimum. Even though England received more rainfallthe warm weather causing evaporation left theland dry and workable, as averagetemperatures rose across Europe people 6 roughly between theWasatch Mountainsand the Sierra Nevada mountains.  established settlements at higher altitudes with some as high as 1300 feetafter 1100 AD. The wet warm weather was a boon to civilization, and it hadhigher temperatures than today with wet but mild winters. The Little Climate Optimum did not affect the world equally, where theCaspian Sea 7 was over 13 feet lower from the 9 th century through the 11 th century than currently. After 1200 AD the elevation of the sea rosedramatically for the next 200 to 300 years. In the Asian steppes, warm periodswith fine summers and with little snow in the winters resulted in water levelsthat were low by modern standards and the southern tip of South America wasdryer than usual. China, according to limited data had somewhat warmerclimate in the 9 th , 10 th , and 11 th centuries and very cold climate in the 12 th and13 th – a Chinese scholar, “Chu Ko-chen” reported that the 8 th and 9 th centurieswere warmer and receive more rainfall, but the climate deterioratesignificantly in the 12 th century. He found records, however, that show the firsthalf of the 13 th century was very moderate; with very cold weather returning inthe 14 th century, the records also showed the major floods and droughts, butthat they suffered little of such during the 9 th and 11 th centuries, with anincrease in the calamities during the 14 th through the 17 th centuries. Japan too had warmer than usual weather in the 11 th century, with the 12 th century experiencing later springs, and the 14 th suffered the return of coldweather. Population Explosion  The Little Climate Optimum coincided with an upsurge of population almosteverywhere, but as there are a few records dealing with only Europe, thevalidity of the statement cannot be verified, what is known as that during thecold and damp “Dark Ages 8 ” the population of Europe had been relativelystagnant. Towns/villages shrank to a few houses clustered behind walls, theoccupants were spent their time in dank hovels, avoiding inclement weather –conditions that were ripe for the spread of disease such as Tuberculosis,Malaria, Influenza and Pneumonia that brought about the death of the childrenand the elderly, those over 30.Albeit historians have failed to agree on why after the 11 th century soared, itmight be better to ask why the population remained so stagnant previous tothe change of climate – warmer and dryer weather. John Keegan in 1993wrote, “The mysterious revival of trade between 1100 and 1300, itself perhapsdue to an equally mysterious rise in the European population from about 40million to about 60 million, in turn revived the life of towns, which through thegrowth of a money economy won funds to protect themselves from dangersbeyond their walls.” 7 Like the Black Sea,the Caspian Sea is a remnant of the ancientParatethys Sea.The Caspian Sea became landlocked about 5.5 million years ago due totectonic upliftand a fall insea level. 8 It lasted from about AD 500 to 1000.
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