THE GREENHOUSE EFFECT
The Greenhouse Effect occurs when greenhouse gases in the Earth's atmosphere trap solar radiation. The yellow flow in the figure to the left represents solar energy hitting the Earth. The numbers indicate percentages of total solar radiation. The clouds in the Earth's atmosphere absorb 25% of the solar energy . Another 25% is reflected back into space. Only about 45% of the incoming solar radiation is absorbed by the oceans and land masses. The pink flows represent heat radiated away from the Earth in the form of infrared radiation. Greenhouse gases such as carbon dioxide, methane, and water vapor reflect some of the infrared radiation back towards Earth, thereby causing a rise in global temperature. ("Greenhouse Effect" image & text source: NASA, Jet Propulsion Laboratory.)
Global warming is not just a question of the temperatures increasing slightly over time as pollution increases. The past temperature changes and future predicted changes may not seem alarming to most people. Global mean temperatures have "only" increased about 0.6°C (plus or minus 0.2°C) since the late-19th century, and about 0.4°F (0.2 to 0.3°C) over the past 25 years, the period with the most credible data. (National Research Council)[ report "Reconciling Observations of Global Temperature Change)] These figures appear relatively small due to the fact that warming has not been equal around the globe. Some areas have, in fact, cooled over the last century while others have increased up to 10°C. The Intergovernmental Panel on Climate Change (IPCC) projects a global temperature increase of anywhere from 1.4 - 5.8°C from 1990-2100. "In the opinion of the panel, the warming trend in global-mean surface temperature observations during the past 20 years is undoubtedly real and is substantially greater than the average rate of warming during the twentieth century." (National Research Council) We do know that human activities are quickly adding to the greenhouse gasses and that some changes have already begun to occur. The big question, which is just now beginning to be answered, is 'What do these environmental changes mean to us humans? There are two parts to this question.
First, there are the major changes that have already occurred as a result of these seemingly small temperature variations. A recent global event indicator was the 1997-1998 El Niño phenomenon. Even the small temperature changes that have already occurred have been blamed for the increase in frequency and severity of the El Niño phenomenon, which is now every 3-5 years instead of the previous cycle of every 5-7 years. Archaeological studies show that El Niños have been occurring naturally for thousands of years. However, the frequency and severity are believed to be increasing as the global warming continues (see graph below courtesy: NOAA/University of Colorado at Boulder). The 1997-1998 El Niño event alone had enormous impact on many areas around the globe, causing thousands of human casualties and destruction adding up to over $90 billion in damage worldwide (United Nations Environment Programme, 2002), with the poor in developing countries suffering the greatest losses.
- Eight of the 10 warmest years since 1860 have occurred within the last decade. (Black, R., 2005).
- Ocean temperatures recorded in the Northern Hemisphere Atlantic Ocean were the hottest on record. (Black, R., 2005)
- Current levels of the greenhouse gases carbon dioxide and methane in the atmosphere are higher now than at any time in the past 650,000 years. (Black, R., 2005)
- The loss of ice from Greenland doubled between 1996 and 2005, as its glaciers flowed faster into the ocean in response to a generally warmer climate. (JPL/ NASA, 2006)
- Mount Kilimanjaro has lost 75% of its ice cap since 1912. The ice on Africa's tallest peak could vanish entirely within 15 years, along with the other remaining African and South American Ice Caps. (Thompson, L., 2001).
- Montana will lose all the glaciers in Glacier National Park by 2030 if current trends in climate change continue. (The Associated Press, 2006)
- Since 1850, one-half of the volume of Europe’s Alpine glaciers have disappeared and it is thought that by the end of the century half of the remainder, will have vanished (BBC Weather Centre)
- Diseases like dengue fever (a tropical illness)are expanding their reach northward in the U.S. (www.Time.com).
- Butterflies are relocating to higher latitudes. The Edith's Checkerspot butterfly of western North America has moved almost 60 miles north in 100 years (www.Time.com).
- There were 562 tornadoes in the United States in May 2003, more than any month on record (www.BBC.CO.UK and www.CNN.com).
- In the last 100 years, sea levels have risen by 10-20 centimeters globally and future rises are predicted to be much greater than this. Although melting glaciers aren’t the main cause of rising sea levels, the effects of glaciers certainly contributes and is a concern to scientists (www.BBC.com). Rising sea levels are thought to be the result of the sea absorbing heat from the atmosphere, causing it to expand and therefore creating a rising sea level.
- Cape Hatteras Lighthouse was 1,500 feet from the North Carolina shoreline when it was built in 1870. By the late 1980's, the ocean had crept to within 160 feet, and the lighthouse had to be moved to avoid collapse (www.Time.com).
- Brazilian shoreline in the region of Recife has receded more than 6 feet a year from 1915 to 1950 and more than 8 feet a year from 1985 to 1995 (www.Time.com).
- Mid-range estimates indicated that 24%, or more than 1 million, of existing animal and plant species will eventually become extinct due to climate change projected to occur by 2050, if global warming pollution is not curtailed (Nature article "Extinction Risk from Climate Change Study" 2004).
- A Rhode Island-sized ice chunk (called the Larsen B ice shelf) fell off the Antarctic Peninsula in 2002. "With the disappearance of ice shelves that have existed for thousands of years, you rather rapidly run out of other explanations" (The New York Times interview with Dr. Theodore A. Scambos, a glaciologist at the National Snow and Ice Data Center).
- The unprecedented warming has led to a pattern of ice shelf loss on the eastern side of the Antarctic Peninsula not seen in 12,000 years (British Antarctic Survey article "Satellite Spies on Doomed Antarctic Ice Shelf" March 2002).
- Earth's coral is disappearing at alarming rates. In some parts of the Indian Ocean, mortality is as high as 90 percent. Some corals more than 1000 years old have recently died (www.NOAA.gov).
- Australia's Great Barrier Reef will lose most of its coral cover by 2050 and, at worst, the world's largest coral system could collapse by 2100 because of global warming (http://www.cleanbeaches.org/ from study by Queensland University's Centre for Marine Studies).
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Approximately 16% of the world’s coral reefs were effectively destroyed during the major El Niño and La Niña climate change events of 1997-98 (http://www.iucn.org/ "Status of Coral Reefs the World: 2004", according to an assessments of more than 240 contributors from 98 countries).
Secondly
there is
the part question as to how
fast these changes will occur. Most predictions of global warming are based upon the
assumption that the increase in greenhouse gases will result in a gradual
change in global temperatures that will, in turn, cause slow changes in our weather
patterns. The majority of environmental and
economic scenarios and assumed effects are being based upon this slow change
assumption. There
are, however, several recent studies which show that the global temperature has and
may again, change very quickly. "Available evidence suggests that abrupt climate changes are not only possible but likely in the future, potentially with large impacts on ecosystems and societies.”
(US National Academy of Sciences [NAS],2002). This has given rise to more focused research into likely causes of
abrupt or sudden events, especially the role of important processes such as the ocean's
"thermohaline circulation" so named from the Greek words “thermos” (heat) and “halos” (salt). 
The oceans play a major role in regulating the Earth’s climate. The ocean slowly circulates and in doing so, redistributes huge amounts of heat around the planet. This contributes to the conditions that ultimately lead to storms, hurricanes, severe winters, monsoon seasons, El Niños, rainfall patterns, and other climate fluctuations. There is no question whether or not a change in ocean currents will greatly effect the global climate or that this has occurred in the past, as deep-sea sediments and ice-sheet core samples show. These sample show the following dramatic changes:
- The Younger Dryas —about 12,700 years ago, average temperatures in the North Atlantic region abruptly plummeted nearly 5°C and remained that way for 1,300 years before rapidly warming again.
- The 8,200-Year Event —A similar abrupt cooling occurred 8,200 years ago. It was not so severe and lasted only about a century. But if a similar cooling event occurred today, it would be catastrophic.
- The Medieval Period —An abrupt warming took place about 1,000 years ago. It was not nearly so dramatic as past events, but it nevertheless allowed the Norse to establish settlements in Greenland.
- The Little Ice Age —The Norse abandoned their Greenland settlements when the climate turned abruptly colder 700 years ago.
Between 1300 and 1850, severe winters had profound agricultural, economic, and political impacts in Europe. In the past, these abrupt changes have had natural causes. The question is are current human activities able to change the ocean circulation (bullet point text source above: Woods Hole Oceanographic Institution www.whoi.edu).
The ocean conveyor is powered by the sinking of cold, salty (denser) waters in the North Atlantic Ocean. This water flows slowly at great depths into the South Atlantic and eventually throughout the world’s oceans. The void created by the sinking water pulls warm, salty surface waters northward distributing the heat to the northern latitudes. The heat is absorbed by the atmosphere which is further distributed by the prevailing eastward winds, warming Europe. If the level of salinity in the North Atlantic water decreases too much the water would stop sinking and the heat conveying Gulf Stream would stop. This would quickly make European and North American temperatures decrease. In turn, this would alter the hydrological cycle globally, causing flooding and droughts. The El Niño phenomenon is one recent indicator that ocean temperature can effect much of our planet. One theory is that global warming will speed this process by melting the ice caps, increasing precipitation, and increasing runoff from the continents thereby diluting the salinity of the ocean.
The abrupt climate change phenomenon has been well established over the last decade by ocean, earth and atmosphere scientists at institutions worldwide. However, this concept does not seem to have been appreciated by economists, policy makers, and political and business leaders worldwide. Recently, this very real possibility seems to have caught the attention of some news publishers as more stories begin to surface. Following are some extractions from recent articles:
- "Sub-polar seas bordering the North Atlantic have become noticeably less salty since the mid-1960s, especially in the last decade. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments. This has resulted in a freshening of the deep ocean in the North Atlantic, which in the past disrupted the Ocean Conveyor and caused abrupt climate changes." (B. Dickson, et. al., in Nature, April 2002)
- “The changes observed over the last several decades are likely mostly due to human activities...." (National Research Council (NRC, 2001))
- "Many scientific observations indicate that the Earth may be undergoing a period of relatively rapid change on timescales of decades to centuries, when compared to historical rates of change on similar timescales." (U.S. Global Change Research Program and Climate Change Research Initiative) www.usgcrp.gov (Participants in the USGCRP include the Departments of Agriculture, Commerce [National Oceanic and Atmospheric Administration], Defense, Energy, Health and Human Services, Interior [U.S. Geological Survey], State, and Transportation; the U.S. Environmental Protection Agency; the National Aeronautics and Space Administration; the National Science Foundation; the Smithsonian Institution, the Office of Science and Technology Policy, the Office of Management and Budget, and the Council on Environmental Quality.)
- "Although humans are relative newcomers in the vast scale of the Earth’s geological history, we have become agents of environmental change ... Atmospheric emissions of greenhouse gases and pollutants, and extensive changes in the land surface, have potential consequences for global and regional climate, weather, and air quality, the Earth’s protective shield of stratospheric ozone, the distribution and abundance of many plant and animal species, and the health of ecosystems and their ability to provide life-supporting goods and services." (www.usgcrp.gov)
- "To me, the question of the environment is more ominous than that of peace and war...... I'm more worried about global warming than I am of any major military conflict." Source: Hans Blix, Former United Nations Weapons Inspector (March 13 2003 Interview with John Norris of MTV News http://www.mtv.com/bands/i/iraq/news_feature_031203/index.jhtml )
- “... stabilization of greenhouse gas concentrations in Earth’s atmosphere at a level that would prevent
dangerous anthropogenic interference with the climate system.” In order to achieve
this long-term goal, net emissions of greenhouse gases on a global scale must ultimately
approach levels that are lower than they are today and, in the cases of the most
important gases, significantly so. (United
Nations Framework Convention on Climate Change (UNFCCC))
Reduce, Reuse and Recycle
Less production and consumption will reduce air pollution.
Reduce
or eliminate the use of products made with or which
contain chlorofluorocarbons (CFC's)
Reduce your vehicle pollution
Reduce consumption of electricity which is
produced in a non-environmentally safe manner.
Consume less pesticide-dependant foods.
Use propane or natural gas
grills, if possible, as they pollute less than charcoal with lighter fluid.
Use low or no VOC
(volatile organic compound) products. instead use water based paints, glues etc.
VOC's include gasoline,
industrial chemicals such as benzene, solvents such as toluene and xylene,
and perchloroethylene (principal dry cleaning solvent). VOC's are also released
from burning fuel, such as gasoline, wood, coal, natural gas and from
solvents, paints, glues, and other products used at home or work. In
addition to being pollutants some of these are dangerous carcinogens and you
should not use them for this reason too.
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