Monday, 5 October 2009

A Chronology of Climate Change

source: By Derek Kelly, PhD

Scam, noun: a swindle, a fraudulent arrangement.

During most of the last billion years the Earth did not have permanent ice sheets. Nevertheless, at times large areas of the globe were covered with vast sheets of ice. Such times are known as glaciations. In the past 2 million to 3 million years, the temperature of the Earth has changed (warmed or cooled) at least 17 times, some say 33, with glaciations that last about 100,000 years interrupted by warm periods that last about 10,000 years.

The last glaciation began 70,000 years ago and ended about 10,000 years ago. The Earth was a lot colder than it is now; snow and ice had accumulated on a lot of the land, glaciers existed on large areas and the sea levels were lower.

15,000 years ago: The last glaciation reaches a peak, with continental glaciers that cover a lot of the sub-polar and polar areas of the land areas of Earth. In North America, all of New England and all of the Great Lakes area, most of Ohio, Indiana, Minnesota and the North Dakotas, lie under ice sheets hundreds of meters thick. More than 37 million cubic kilometers of ice was tied up in these global sheets of ice. The average temperature on the surface of the Earth is estimated to have been cooler by approximately 6 degrees Celsius than currently. The sea level was more than 90 meters lower than currently.

15,000 years ago to 6,000 years ago: Global warming begins. The sheets of ice melt, and sea levels rise. Some heat source causes approximately 37 million cubic kilometers of ice to melt in approximately 9,000 years. Around 9,500 years ago, the last of the Northern European sheets of ice leave Scandinavia. Around 7,500 years ago, the last of the American sheets of ice leave Canada. This warming is neither stable nor the same everywhere. There are periods when mountain glaciers advance, and periods when they withdraw. These climatic changes vary extensively from place to place, with some areas affected while others are not. The tendency of warming is global and obvious, but very uneven. The causes of this period of warming are unknown.

8,000 years ago to 4,000 years ago: About 6,000 years ago, temperatures on the surface of Earth are about 3 degrees warmer than currently. The Arctic Ocean is ice-free, and mountain glaciers have disappeared from the mountains of Norway and the Alps in Europe, and from the Rocky Mountains of the United States and Canada. The ocean of the world is some three meters higher than currently. A lot of the present desert of the Sahara has a more humid, savannah-like climate, with giraffes and savannah fauna species.

4,000 years ago to AD 900: Global cooling begins. The Arctic Ocean freezes over, mountain glaciers form once more in the Rocky Mountains, in Norway and in the Alps. The Black Sea freezes over several times, and ice forms on the Nile in Egypt. Northern Europe gets a lot wetter, and the marshes develop again in previously dry areas. The sea level drops to approximately its present level. The temperatures on the surface of the Earth are about 0.5-1 degree cooler than at present. The causes of this period of cooling are unknown.

AD 1000 to 1500: This period has quick, but uneven, warming of the climate of the Northern Hemisphere. The North Atlantic becomes ice-free and Norse exploration as far as North America takes place. The Norse colonies in Greenland even export crop surpluses to Scandinavia. Wine grapes grow in southern Britain. The temperatures are from 3-8 degrees warmer than currently. The period lasts only a brief 500 years. By the year 1500, it has vanished. The Earth experiences as much warming between the 11th and the 13th century as is now predicted by global-warming scientists for the next century. The causes of this period of warming are unknown.

1430 to 1880: This is a period of the fast but uneven cooling of Northern Hemisphere climates. Norwegian glaciers advance to their most distant extension in post-glacial times. The northern forests disappear, to be replaced with tundra. Severe winters characterize a lot of Europe and North America. The channels and rivers get colder, the snows get heavy, and the summers cool and short. The temperatures on the surface of the world are about 0.5-1.5 degrees cooler than present. In the United States, 1816 is known as the "year with no summer". Snow falls in New England in June. The widespread failure of crops and deaths due to hypothermia are common. The causes of this period of cooling are unknown.

1880 to 1940: A period of warming. The mountain glaciers recede and the ice in the Arctic Ocean begins to melt again. The causes of this period of warming are unknown.

1940 to 1977: Cooling period. The temperatures are cooler than currently. Mountain glaciers recede, and some begin to advance. The tabloids inform us of widespread catastrophes due to the "New Glaciation". The causes of this period of cooling are unknown.

1977 to present: Warming period. The summer of 2003 is said to be the warmest one since the Middle Ages. The tabloids notify us of widespread catastrophes due to "global warming". The causes of warming are discovered - humanity and its carbon-dioxide-generating fossil-fuel use and deforestation.

Add To FacebookTwit ThisAdd To RedditDigg ThisStumble ThisFav This With Technorati

No comments:

Post a Comment