FR friend Carol Bone put this together, that is worth a read by all those who chance upon this website:

Earth’s Climate Change

• Earth’s climate is one of continual change.  It has been much warmer than the present and much colder.  
• For most of the Earth’s history global temperatures were 8 to 15° C warmer than today.
• Over the last 2 billion years, glaciers have advanced and retreated many times.
• During the last major ice age, massive glaciers buried much of North America, Europe, and Asia.  Sea levels were 300 feet lower than today.  
• Then about 14,000 years ago, glaciers began to retreat.   By 8,000 years ago, the land bridge across the Bering Strait was under water, stopping the migration of humans and animals to North America.   Forests replaced sheets of ice. 
• The earth cooled again about 12,000 to 10,500 years ago, and then warmed again.   
• Around 5000 to 3000 BC, when many ancient civilizations began, temperatures were warmer than today.  
• From 3000 to 2000 BC a cooling trend occurred.  This cooling caused drops in sea-level and the emergence of many islands and coastal areas that are still above sea-level today.  
• A warming trend took place from 2000 to 1500 BC, followed by colder conditions. 
• Colder temperatures from 1500 – 750 BC caused glaciers to grow again and the oceans to drop between 2 to 3 meters below present day levels.
• Temperatures warmed again from about 750 BC to 150 BC but did not get as warm as 3000 BC.
• During the Roman Empire (150 BC – 300 AD) a cooling began that lasted until about 900 AD.   The Nile River froze in 829 AD, and the Black Sea froze in 800-801 AD.
• The period from 900 – 1200 AD was warmer than 3000 BC.  During this time, the Vikings established settlements on Greenland and Iceland.  
• From 1550 to 1850 AD global temperatures cooled again, producing the Little Ice Age.   The average temperature of the Northern Hemisphere was about one degree Celsius lower than today.  Cold weather in Iceland from 1753 and 1759 caused 25% of the population to die from crop failure and famine. 
• Temperatures increased from 1900 to 1940, then decreased from 1940 to 1975.  Now temperatures are increasing back to about where they were in the 1930’s.  In the last century, the total average annual temperature increase has been so slight that the actual amount is uncertain – perhaps 1/3° C.
• As recently as 2002, the Hubbard Glacier in Alaska advanced and made Russell Fiord into Russell Lake and then receded.

Global warming is exactly what should be happening if everything is normal.  Greenhouse gases like carbon dioxide, water vapor and methane help moderate temperatures, especially at night, by keeping heat from escaping back into space.  Without the greenhouse effect, the average temperature of the Earth would be -18 degrees C.  Natural wetlands produce more greenhouse gas contributions annually than all human sources combined.  The main cause of change in global temperature is due to cycles of the sun’s energy output and Earth’s cycles of orbits about the sun. Other causes are atmospheric and tectonic.  It seems whenever there is a large land mass at one of the Earth’s poles, either the north pole or south pole, there are ice ages.   Our planet isn’t the only one with a changing climate.  The ice caps of Mars are now melting, but there are no SUV’s on Mars. We are currently in a short, warm period between glacial advances.  At some time, the earth will enter another ice age.  Doesn’t living on a warming Earth, with longer summers and shorter winters, sound better than a return to an ice age with shorter summer  s, longer winters and growing glaciers?   Let’s be thankful we live in an era of slight global warming.

(Information gathered from various internet sources by Carol Bone.)

This entry was posted on Thursday, August 23rd, 2007 at 12:00 am and is filed under Blog Posts.