Friday, May 29, 2009

Global Warming, the Carbon Cycle and Other Thoughts

Jeremy Leggett of Solarcentury outlines only two visions of the future: accelerating the use of fossil-fuel and nuclear without carbon capture into some dark and horrible future or expanding the use of renewable energy sources (specifically solar, wind and water) with falling clean energy prices, and ultimately mass market use of renewable sources of energy supplying the world’s needs. Nigel Calder co-author of “The Chilling Stars, A new theory of climate change” sees the world much differently. They believe in the Solar Irradiance theories and feel that the effects of greenhouse gases are likely to be a good deal less than advertised based on a different theory of climate change.
There is more than one theory of climate change and I certainly do not know the true importance of the factors that can impact global temperature change, but I am unwilling to dismiss any theory or area of investigation at this stage. The world is not black and white and our knowledge of the interlacing systems that make up the ecosystems of the earth is truly limited. The visions of the future are not cut and dried. The real world is the one that is subtly interconnected where we have limited knowledge and resources and we need to evaluate the best use of our resources, financial, intellectual, natural, and emotional.
Many greenhouse gases occur naturally in the atmosphere and are also produced by man’s activities, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are entirely synthetic. Those that are synthetic, man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF6). Atmospheric concentrations of both the natural and man-made gases are reported to have been rising over the last few centuries. With increasing global population and technology our reliance on fossil fuels (such as coal, oil and natural gas) has increased, so emissions of greenhouse gases have risen. While gases such as carbon dioxide occur naturally in the atmosphere, man’s activities through burning forest lands, or mining and burning coal, we moved carbon from solid storage to its gaseous state, increasing atmospheric concentrations.

Carbon dioxide levels fluctuate throughout the year, but appear to be consistently rising. From 1970 to 2000, the concentration rose by about 1.5 ppm each year, but since 2000 it has risen to an average 2.1ppm. (ppm is a part per million, a percentage is a part per hundred) These changes are believed to threaten the global environmental equilibrium. According to the National Climate Data Center at NOAA CO2 levels have increased from 280 parts per million in 1850 to 385 parts per million today. According to data from the US Department of Energy, and National Climate Data Center, the carbon in the atmosphere has increased 24% since pre-industrial times but only about 4% of that increase was attributed to human activity. Though this sounds incredibly small, many believe that this small percentage is the tipping point for the carbon cycle and the cause of global warming, the increase in the average temperature that was recorded during the past century.

Water Vapor is the most abundant greenhouse gas in the atmosphere accounting for 94%. It is believed by many that the small change in CO2 emissions due to man causes large changes in water vapor concentrations due to a climate feedback cycle. As the temperature of the atmosphere rises, more water is evaporated from surface sources. Because the air is warmer, it is able to 'hold' more water leading to more water vapor in the atmosphere. As a greenhouse gas, the higher concentration of water vapor is then able to absorb more thermal IR energy radiated from the Earth, thus further warming the atmosphere. The warmer atmosphere can then hold more water vapor and so on and so forth. The proposals to reduce greenhouse gases are intended to move the ecological cycle back from the tipping point.

The best measurements of global air temperatures come from our weather satellites, and they reportedly show fluctuations, but no overall change in air temperature since 1999. (Though record warm and cold years have been recorded since that time the average seems to be the same.) The leveling off of global warming as measured by air temperature while CO2 levels continue to increase is heralded by the school of thought, which says that the sun drives climate changes more emphatically than greenhouse gases do.

Solar cosmic rays intensity and frequency affect the production rate of radiocarbon, C14, the substance that is used by archaeologists to date objects. The original C14 content is due to the amount present in the air at the time of death or encapsulation. The atoms gradually decay back to nitrogen and thus provide a method for dating materials. It was discovered in 1958 by Hessel de Vries of Gronigen that the rate of C14 production varies. Measurements in well-dated annual rings of growth in ancient trees were the key to identifying this. The C14 variations allowed the variation in the solar production of cosmic rays to be measured. Roger Bray of the New Zealand Department of Scientific and Industrial Research then Jack Eddy of High Altitude Observatory in Colorado documented the correlation of solar cosmic rays and the earth’s climate changes.

After becoming much more active during the 20th century, the sun now stands at a high but roughly level state of activity. Solar physicists warn of possible global cooling, if solar activity falls. The earth is such a complicated system with so many inputs and dependent cycles that an accurate model has not been developed and is unlikely to be developed to test these theories. If something as relatively simple as the world economy could not be adequately modeled and controlled to predict and prevent a global recession, how is the more complicated system of earth to be simplified and controlled?

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