Global Warming

Global Warming

Eric R. Pianka

Physics and chemistry have given us two Laws of Thermodynamics: the first deals with conservation of matter and energy, while the second deals with increase in disorder (entropy). An understanding of basic thermodynamics is essential to grasp the full implications of energy usage by humans.

The first law "conservation of matter and energy" states that matter and energy cannot be created or destroyed. Matter and energy can be transformed, and energy can be converted from one form into another, but the total of the equivalent amounts of both must always remain constant. Light can be changed into heat, kinetic energy, and/or potential energy. Whenever energy is converted from one form into another, some of it is given off as heat, which is the most random form of energy. Indeed, the only energy conversion that is 100 percent efficient is conversion to heat, or burning. Aliquots of dried organisms can be burned in "bomb calorimeters" to determine how much energy is stored in their tissues. Energy can be measured in a variety of different units such as ergs and joules, but heat energy or calories is the common denominator.

A certain amount of solar energy falls on Earth's surface at any given place and time, creating heat. Unless this same amount of heat is dissipated back out into space, Earth will warm. Conversely, if more heat is re-radiated back out into space than is received, the planet will cool down.

Earth's atmosphere is in a complex equilibrium. Certain gases in the atmosphere, especially carbon dioxide, prevent re-radiation of solar energy holding heat in thus warming the planet (the "greenhouse effect"). The concentration of CO2 has risen steadily over the last 40 years and continues to rise due to deforestation and burning of fossil fuels. This increase in atmospheric carbon dioxide has enhanced atmospheric heat retention and would have produced global warming sooner except for a fortuitous spin-off of atmospheric pollution -- particulate matter increased earth's albedo (reflectance of solar irradiation), so that less solar energy penetrates to the surface (volcanic ash in the atmosphere has the same effect). Fortuitously, these two opposing phenomena more or less balanced one another for some time, but now the balance has clearly shifted and the enhanced "greenhouse effect" is leading to rapid global warming. Long-held meteorological records the world over have been broken regularly during the last couple of decades.

Until recently, Earth was in a delicate thermal balance with heat gained approximately equal to heat lost, cycling within a fairly narrow range as glaciation produced cooling and deglaciation produced warming with a periodicity of about 100,000+ years (see methane graph below). But now, due to burning fossil fuels over the last century, humans have increased CO2 levels, which in turn have enhanced the greenhouse effect and prolonged the present deglaciation/warming trend for the last 10,000 years, whereas former warm peaks in the cycle were much shorter (again, see the graph below). Holding in more solar energy has lengthened the period of global warming.

Even if humans were not adding vast amounts of excess heat by burning non-renewable fossil fuels, the planet might no longer be able to dissipate the heat it receives from normal incident solar radiation fast enough to stay in balance. Many people naively think that access to more and more energy will somehow 'solve the energy crisis.' In fact, to stop global warming and get the Earth back into its normal thermal cycle, we would need to greatly reduce our energy usage. It might be nice if somehow we could also scrub some carbon dioxide out of the atmosphere, as that would increase the capacity for heat dissipation thus allowing us to use more energy without global warming. Unfortunately, this is a pipedream, because cleaning many megatons of carbon dioxide out of the atmosphere isn't really very feasible. We may well have already reached the point of no return.

Weather is driven by the thermal differential between the surface and atmosphere versus that of outer space, which remains cold and constant. As Earth warms, this difference increases and climate goes into convulsions -- droughts and heat spells are intensified and storms become more intense. With the melting of glaciers and ice caps (see below), more water enters the atmosphere, changing the hydrological cycle. We can expect more flooding, more tornados, bigger and more frequent hurricanes and monsoons. Weather is rapidly becoming more variable and more extreme. The exact timetable for these changes is uncertain, but data and current events suggest that climate changes are taking place during human lifetimes. A tipping point, or point of no return, may well have already been reached (see below).

Despite cries that climate change is not occurring, usually supported by parties with serious conflicts of interest (such as pseudo-scientists under the payroll of big oil), evidence for global warming is unequivocal (for further documentation and expert opinion, see also links provided below). For example, study the following two graphs of long-term climate change from the National Oceanic and Atmospheric Administration.

Long-term averages from the global network of weather stations are plotted over the last century from 1880 to the present. Below average deviations are shown in blue, above average ones are in red.

Notice that land masses began to warm before the oceans and that land temperatures have increased more than those of the oceans. Water has a high specific heat, which means that a considerable amount of heat energy is required to raise its temperature -- indeed the oceans have acted as a heat sink which has kept land temperatures from rising as much as they would have without the large bodies of water. However, the oceans are now warming and acidifying, both of which have caused endosymbiotic coral zooxanthellae to die off (so called "bleaching of coral reefs"). Warming of surface seawaters could change ocean currents, even disrupting heat pumps such as those that warm northern Europe. Average global temperatures of both land and oceans have been above average every year for the past 25 years, a clear indication that climate changes are taking place during human lifetimes.

This plot separates thermal global averages for the northern and southern hemispheres. Note that temperatures in the northern hemisphere, where most of the people are located, started to rise earlier and have become warmer than the southern hemisphere.


Earth's poles are warming more rapidly than other areas and they are critical to global climate because as they warm, long-frozen carbon dioxide and methane is being released into the atmosphere. Everyone should be familiar with the increasing carbon dioxide levels in the atmosphere due to human activities, especially burning of fossil fuels. People are less familiar with the recent surge in methane levels (see graph below). Like CO2, methane is a greenhouse gas which holds in heat. One molecule of methane is equivalent to about 20 molecules of carbon dioxide in terms of its effects on global warming. Long frozen fossil methane is being released from thawing permafrost and from the deep oceans at an ever accelerating rate. As temperatures rise, more methane bubbles up to the surface, further raising temperatures in an ever increasing positive feedback loop. Is there a critical "tipping point" at which the state of Earth's surface will change drastically, and if, so, what is it and when will it be reached? Some experts think this tipping point has already been crossed.


This plot is based on air samples of known age dating back almost half a million years taken from Antarctic and Greenland ice cores. Temperature changes are plotted in red, CO2 in fuzzy gray, and methane levels in black. These changes are caused by complex periodic fluctuations in Earth's orbit and the inclination of its axis known as the Milankovitch cycles. Human activities have strongly impacted climate during the last 10,000 years.

Four prolonged ice ages are clearly evident. Notice the four spikes in temperature spaced roughly every 100,000+ years. Earth is presently in a warm interglacial phase with CO2 levels well above any that have been experienced during the last 400,000 years.

Notice also that the last thermal spike has been prolonged a lot compared to the three earlier ones. Earth should have gone into a colder glacial state but has stayed warm for roughly the last 10,000 years. This extended warm period corresponds to the invention of agriculture and the resulting surge in human population and it is almost certainly due to human activities, especially deforestation and burning of fossil fuels. Notice also the very recent, exceedingly steep, spike in methane production! This could well portend the onset of a powerful positive feedback loop for very rapid global warming.

Sea levels have risen almost a foot during the last century. Some experts think that eventually all Earth's glaciers will melt and that sea levels will be substantially higher, innudating all major coastal cities. One very large Antarctic glacier, currently on land, is melting and as its melt water lubricates its underside, it is sliding towards the sea at an accelerating rate. Remember "the tip of the iceberg" (90% is underwater)? When that huge glacier finally plunges into the ocean, sea levels will rise almost instantly all around the world. Talk about a tipping point!



Another very dangerous man-made molecule, trifluoromethyl sulfur pentafluoride SF5CF3, has recently begun to appear in the atmosphere. Each molecule of this greenhouse gas has 18,000 times the effect of one molecule of carbon dioxide on heat retention. Although SF5CF3 is present in very small amounts, it is exceedingly stable (half life=1000 years) and is increasing at a rate of about 6% per year [Sturges et al (2000) Science 289:611-613].

Of course, humans are clever, so clever that we have actually figured out how to convert matter into energy exploiting fission and fusion. Some NASA engineers are also proposing to beam more solar energy from outer space to the planet's surface. Such people think that we can use all the energy we want or can get in any way we want. Nuclear energy is virtually limitless, but it carries serious environmental hazards (particularly thermal pollution and radioactive waste). Access to such excess energy will lead to our downfall (see below).

Unlimited cheap clean energy, such as that so ardently hoped for in the concept of cold fusion, would actually be one of the worst things that could possibly befall humanity. Such energy would enable massive energy consumption and habitat destruction. Mountains would be leveled and terraced, massive water canals would be dug, ocean water distilled, water would be pumped and deserts turned into green fields of crops. Human populations would grow even higher until the last vestiges of natural habitats are all destroyed. Heat dissipation will ultimately dictate limits, for when more heat is produced than can be dissipated, the resulting thermal pollution will quickly warm the planet to the point that all life is threatened, the ultimate ecocatastrophe. In fact, this scenario is already happening even as many people remain locked in denial refusing to admit that a crisis even exists.

The world's human population of almost 7 billion is increasingly destructive in its various 'constructive' economic enterprises, whose goal is growth and development, which convert huge amounts of energy into heat and waste products. Winston Churchill once said "Men occasionally stumble on to the truth, but most of them pick themselves up and hurry off as if nothing had happened." To keep spirits up, politicians invent expressions like "sustainable growth" and "sustainable development." People do not analyze these expressions, but prefer blissful ignorance vis-a-vis their meaning. However, stringing such antonyms together merely creates irresponsible oxymorons. Physical laws of nature will go on about their business of running the Universe, while most people remain oblivious to the impending emergency we have caused.

Remember that ancient Chinese curse: "may you live in interesting times"? You lucked out, for right now is undoubtedly among the most interesting times in the entire history of humanity. Not only do we get to face population overshoot, but also all of its many consequences: ferocious weather, crop failures, energy shortages, shortages of food and water, economic collapse, toxic wastes, pollution of our air and water, famine, pestilence, war, loss of biodiversity, the devaluation of human life, not to mention the impending demise of civilization itself.


Links:
  • Download Eric Chaisson article on global waste heat
  • National Oceanic and Atmospheric Administration website
  • Intergovernmental Panel on Climate Change website
  • New York Times: on ice melting on top of the world (with maps)
  • The Great Climate Debate-- Morrison
  • Low Lying Pacific Islands Inundated
  • Interview with meteorologist Dr. Chris Rapley (50 minutes)
  • Download Burkhardt essay on energy technology
  • Enyclopedia of Earth global warming website
  • Grist Environmental News website
  • Real Climatologist's website
  • Population Bomb versus Climate Change
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