Mother Nature does provide ample means for climate change without the help of man. Minor changes in the Earth’s orbit and tilt are thought to be the most significant causal factors for the Ice Ages. The sun itself has varied in intensity, causing warming or cooling. Volcanic activity throws debris into the atmosphere along with gases (including CO
2). In prehistoric times, volcanic eruptions were a major source of CO
2 and other greenhouse gases contributing to global warming. In more recent times, major volcanic eruptions have caused short-term climate changes, often causing cooling due to debris caught in the upper atmosphere reflecting the sun’s rays.
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Although studies suggest the Earth was already in a slight warming cycle, the Intergovernmental Panel on Climate Change (IPCC) studies also confirm that the amount of CO
2 in the atmosphere has increased by about 35% during the industrial era as a result of burning fossil fuels and deforestation. “While many factors continue to influence climate, scientists have determined that human activities have become a dominant force, and are responsible for most of the warming observed over the past 50 years. Human-caused climate change has resulted primarily from
changes in the amounts of greenhouse gases in the atmosphere, but also from changes in small particles (aerosols), as well as from changes in land use, for example.”
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A historical record of atmospheric CO
2 , spanning hundreds of thousands of years, was obtained through analysis of ice cores from Greenland and Antarctica. By measuring the composition of air enclosed in bubbles in the ice, IPCC scientists have deduced the CO
2 levels rose exponentially throughout the industrial era along with methane and nitrous oxide levels, two other major greenhouse gases. Climate model studies verified the connection between greenhouse gases and temperature.
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A small rise in global temperatures has a significant effect on the interconnected global weather system. Ocean currents, wind, rainfall, atmospheric pressure, reflection of sunlight by ice and snow, debris in the atmosphere - all of these factors and many more combine to create climate and weather. So what happens if temperatures continue to climb? IPCC scientists tell us sea levels will rise, the glaciers will continue to recede (causing shortages in fresh water), the polar ice cap will continue to melt (
since 1979 we have lost 20% of the polar ice cap), the increase in tropical storms will continue, and
severity of storms will increase.
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Ocean currents are an essential part of our climate and weather patterns. The MOC (Meridional Overturning Circulation) begins in the North Atlantic where water evaporates to fall as rain, leaving behind its salt. Colder water and saltier water, being denser than warmer and less salient water, falls to the ocean depths and is pushed south as a current, past the equator where it warms and begins to rise. Winds blow the water northward to complete the cycle. Though the shutdown of the MOC is considered unlikely, there is concern that climate change may alter or slow ocean currents causing considerable changes in weather.
IPCC scientists state concern that we may be approaching the tipping point where factors outside of our control could accelerate global warming, causing abrupt climate change. Factors include the release of CO
2 from permafrost as the ice cap continues to recede, warming due to the loss of reflection from polar and glacier ice, or a slow down or shutdown of the Atlantic meridional overturning circulation (MOC), the ocean current that brings large amounts of heat to North America and Western Europe. They
Global Warming: Myth or Fact?
Issue 3 | January 2010