September 22, 2009
Reports of global warming in the popular press have generally neglected to acknowledge natural causes that drive our weather patterns and climate. The following summary
lists those more commonly known, beginning close and proceeding outward.
1. Geothermal. The enormous energy of earth's molten interior moves continental masses, generates hot springs and occasionally spews volcanic magma into the atmosphere. In the vicinity of rifts on the ocean floor, exploration submersibles have photographed water boiling (a potential incubator for hurricanes).
2. Precession variations. The earth's wobble about its spin axis changes the angle of incidence for incoming solar radiation, gradually altering local daylight and nighttime durations.
3. Orbital variations. The varying distances from earth to sun at positions along earth's fluctuating ellipse control the quantity of solar photons reaching us, in proportion to the square of the distance.
4. The sun's turbulent surface activity. As the sun rotates, phenomena in earth's proximity such as solar flares, magnetic storms and sunspots are superimposed upon the energy we receive from nuclear fusion reactions powering the sun.
5. Cosmic rays from our galaxy. This recently considered source has been claimed to influence charged aerosols in our atmosphere, which subsequently affect cloud development.
The popularly promoted accounts reduce a complex climate change process to a simplistic global warming argument based on carbon dioxide and some other compounds in the atmosphere that absorb infrared (IR) radiation. The promoters employ atmospheric temperature measurements of relatively short term trends, extenuate the influence of natural events and emphasize a greenhouse-related rationale. But their greenhouse analogy is scientifically incorrect, and they offer no clean supporting data from experiments carefully designed to minimize confounding by natural influences. Their scientific transgressions originate from misapplication of the electromagnetic spectrum, disregard for three fundamental laws of physics, and the misrepresentation of greenhouse operation and absorption behavior of photons.
Electromagnetic radiation, carried by photons, ranges from gamma rays at the shortest wavelength, most energetic and hottest end of the spectrum, to radio waves at the longest wavelength, least energetic and coldest end. In between, from short to long wavelength, lie X-rays, ultraviolet (UV), visible, IR and microwaves. A photon is a discrete packet (quantum) corresponding to specific wavelengths of this radiant energy (heat).
In common usage, 'absorption' implies physical entrapment, as, for example, water sopped up by a sponge. Every water molecule survives this absorption process and, with sufficient effort, may be reclaimed and recycled. In scientific terminology, however, absorption properly means that a photon converts its quantum of radiant energy to kinetic energy. The discrete packet is not trapped intact; a photon immediately surrenders its energy to the substance absorbing it, vanishes and cannot be recycled. The resultant kinetic energy is manifested as matter (electrons, atoms, ions, molecules) vibrating, shaking, or bumping and jostling neighboring matter. The energy transition is dissipative in compliance with the Second Law of Thermodynamics, which is sometimes described as the spontaneous downhill flow of energy (always high to low, hot to cold), or as dropping a cup of coffee with the cup breaking and coffee spilling everywhere. The suggestion that absorption "traps" a photon, allowing it to be recycled with no energy loss, violates the Second Law and revives earlier fantasies of perpetual motion.
Emission, also compliantly dissipative, is the reverse conversion whereby excess kinetic energy is carried away from highly excited matter as a quantum of radiant energy. A photon of appropriate wavelength emerges, allowing the matter to return to its kinetic comfort zone. Both absorption and emission are mechanisms of energy transfer, and energy levels must match for these transitions to occur. Spectroscopists measure wavelengths where photons appear or disappear in the electromagnetic spectrum to identify participant chemical elements, ions and compounds.
The Stefan-Boltzmann Law is an exponential relationship crucial in evaluating relative energy intensities emitted by stars, planets and greenhouses. It states that the total intensity of emitted radiation is proportional to the emitter's temperature raised to the 4th power, and affirms that the sun's surface, at a temperature of approximately 10,000 degrees Fahrenheit, emits photons whose peak intensity is in the visible region of the electromagnetic spectrum with considerable overlap into the hotter UV and cooler IR regions. By contrast, the earth's surface, which is barely 100 degrees F on average, emits photons at a significantly lower peak intensity in the IR region with no overlap into the visible; the range of IR emitters extends well below the freezing point of water. Wien's Law, which states that the wavelength of maximum intensity is inversely proportional to the temperature of the emitter, completes the task of correlating photons, their wavelengths and relative energy intensities, with their position in the electromagnetic spectrum.
A greenhouse is a physical structure with transparent panels placed to admit solar radiation, but only a narrow range is permitted entry. For example, spectroscopists use similar transparent cells to hold liquid samples for absorption investigations in the visible region of the spectrum, approximately 0.4 to 0.8 micrometer (um) in wavelength, and special quartz cells to extend their investigative range to about 0.2 um into the near UV region. Depending upon the window material chosen, solar radiation entering a greenhouse is somewhere within this visible/UV sub-um region of the spectrum. Suitable window materials that transmit lower energy, longer wavelength IR photons are uncommon. Spectroscopists use sodium chloride (polished rock salt) in the mid IR range 2 to 16 um, which is radiation absorbed by carbon dioxide, methane, water vapor, liquid water, snow, ice, organic compounds (including animal and vegetative, living or decaying), minerals (glass, sand, dirt), plastics--the plethora of IR absorbers makes IR absorption spectroscopy a valuable analytical tool. This region of the solar spectrum neither enters, nor heats, a greenhouse.
Most of the hot sub-um photons allowed entry are absorbed by opaque objects inside the structure, readily dissipating solar energy from a 10,000 degree F emitter into the terrestrial environment of a 100 degree F emitter. Some photons may be reflected back out, demonstrating that "heat" itself is not trapped; reflected photons in the visible region of the spectrum allow someone standing outside to see the interior. The conspicuous heating of a greenhouse is incontrovertible, but the huge energy differential of the dissipative mechanism driving it is not so obvious from our cool terrestrial perspective. Opaque objects convectively dissipate excess kinetic energy to the confined greenhouse atmosphere, which is primarily nitrogen and oxygen. It's this warmed air that's trapped inside. The principle is the same as using wool, fur or layered clothing to trap warm air near the skin. Similarly, cloud cover after sunset effectively behaves like a ceiling to inhibit convective transfers throughout our atmosphere, temporarily trapping warmed daytime air near earth's surface: the basis of the "greenhouse effect" metaphor.
Before sunrise, IR photons emitted inside a greenhouse are at thermal equilibrium with their enclosed environment. Warming of the interior commences as the first rays of sunlight reach the greenhouse windows and hot sub-um photons enter. Carbon dioxide participates in the convective distribution of excess kinetic energy emanating from opaque surfaces, but at only about 0.035% (by volume) of the atmosphere, is less important than the more highly concentrated atmospheric components nitrogen, oxygen, water vapor and argon. As kinetic activity increases, substances unable to accommodate the excess energy through nature's normal shake or bump kinetic transfers emit appropriate photons to find kinetic comfort in their warming environment. Among this cooler, secondary radiation, photons in the mid IR range of the spectrum are immediately reabsorbed by almost everything inside the greenhouse (except nitrogen, oxygen and argon) and disappear, their newly transferred kinetic energy becoming part of the dynamic convection process. As absorbers, trace quantities of carbon dioxide and higher concentrations of water vapor in the greenhouse atmosphere are less relevant than opaque objects, liquid water and interior window surfaces. The Second Law is in firm control as absorption, emission and convection seek equilibrium with the changing thermal environment.
Ironically, the global warming promoters have ignored the reason we build greenhouses: to grow plants. Through the endothermic chemistry of photosynthesis, carbon dioxide plays a major role disproportionate to its trace concentration in the atmosphere. Hot solar sub-um photons supply the energy employed by chlorophyll to tear apart carbon dioxide molecules, producing the substance of vegetation (carbohydrates) and tossing off oxygen gas as a chemical waste in the process; the greenhouse atmosphere becomes diminished in carbon dioxide content and enriched in oxygen. Photosynthesis is not a sequestering activity, as some promoters have misstated. Part of the energy consumed in the endothermic reactions is stored in carbohydrates as chemical energy, a significantly different concept from their "trapped heat" fantasy of carbon dioxide molecules perpetually recycling IR photons. Carbohydrates in various links of our food chain fuel the exothermic chemistry of our metabolism, driven by the oxygen waste, allowing us to live, maintain a body temperature of about 100 degrees F, and function as bona fide IR emitters. Carbon dioxide, source of fuel and oxidizer for our metabolism, is indispensable to our lives. It also cools a greenhouse through its participation in the transformation of radiant energy to stored chemical energy. Despite these attributes, the EPA has declared that carbon dioxide is a pollutant, to be regulated through government edict.
A further example of scientific carelessness in the global warming argument is their statement that "solar radiation" is lost into space by reflection off ice, snow and clouds. Their claim is true for sunlight, the thin region of the electromagnetic spectrum that heats greenhouses. However, it's untrue for solar IR radiation, which is efficiently absorbed by our polar regions, cloud cover, and all earth's ice, snow and water. Rather than being lost into space, solar IR is absorbed by essentially 100% of earth's surface. Their glib observation falsely implies that all wavelengths of solar radiation are equivalent.
Exaggeration of the potency of IR radiation and its influence on an estimated 0.01% increase of carbon dioxide in our atmosphere has led to mischief. It's the stimulus for encouraging development of notoriously inefficient windmill energy, questionable efforts to convert corn carbohydrates to alcoholic fuel, and to impose an economically improvident carbon tax that adds useless costs to all consumers. It has also elicited a reckless proposal to dispense artificial volcanic ash into the atmosphere in order to counter a highly speculative global warming crisis. Nevertheless, the promoters continue pressuring governments to impose their conceits on the general public.
Considering the many misrepresentations and the absence of clean, supporting data, the "science" behind the global warming argument has hardly been "settled." It has yet to be addressed.
Tom Kondis is a retired chemist and consultant with practical experience in absorption and emission spectroscopy using ultraviolet, visible and infrared radiation and experimental investigations with 15 U.S. patents issued.