John Houghton, Global Warming: The Complete Briefing (Cambridge: Cambridge University Press, 1997)

Global Warming: The Essential Facts

Bruce E. Johansen

While a lively debate in political circles and the press questions whether human activity is significantly warming the earth, scientific evidence has been accumulating in support of the idea. Atmospheric scientists such as John Houghton (author of Global Warming: The Complete Briefing, Cambridge University Press, 1997) have been developing historical analyses of rises in "greenhouse gasses" during the last two centuries. The evidence, unobscured by special economic interests that sometimes cloud popular debate, is not at all ambiguous.
          Carbon dioxide, which increases retention of heat within the atmosphere, has risen from roughly 280 parts per million at the dawn of the industrial age (A.D. 1700 on the Christian calendar) to about 360 ppm during the 1990s, a 28.6 per cent increase, according to Houghton's calculations.
          Furthermore, a slow but steady increase in carbon-dioxide concentrations has accelerated markedly after the mid-twentieth century, as industrial capitalism has swept through the third world, changing living standards throughout Asia and among the upper classes of Latin America, among other "developing" nations of the world. Houghton's graphs of carbon-dioxide content as well as other indices which contribute to global warming show a definite acceleration since 1950, which continues today. Increasing populations (as well as deforestation of many remaining wild areas, especially in the tropics) are causing this acceleration along with increasing per-capita consumption levels of energy derived from fossil fuels.
          Contemporary observations indicate that carbon-dioxide content of the atmosphere is increasing by about 1.5 p.p.m. per year, with large annual variations, according to Houghton. Some years, such as 1972 and 1988, atmospheric carbon dioxide has risen 2.5 to 3.0 per cent, while during one year, 1973, it did not increase at all. Over time, however, the composition of the atmosphere is changing to increase the amount of heat retained within the atmosphere. Using these figures, roughly two-thirds of the increase in carbon dioxide since industrialism began has taken place since roughly 1950, within the lifetime of a person who is middle-aged today.
          The addition of other greenhouse gasses, such as chloroflourocarbons (CFCs) intensify retention of heat within the atmosphere. One CFC molecule, according to Houghton, "has a greenhouse effect five to ten thousand times greater than an added molecule of carbon dioxide." (p. 37) Atmospheric CFCs also destroy ozone, which shields life on earth from damaging ultraviolet radiation, but does not increase retention of heat by itself. Most CFC use is being phased out under international protocols, but its effects "will only decrease very slowly next century," writes Houghton. (p. 37)
          Houghton takes his analysis a step beyond tallying historical increases in greenhouse gasses by next presenting an historical analysis of temperature change during the same periods. He finds, for example, that average global temperatures have increased roughly one degree Celsius between 1860 and the middle 1990s.
          Houghton's graphs present tempting opportunities to match increases in temperature to specific events in the history of carbon-dioxide emissions, although explanations probably are not that simple. There is a hump roughly matching World War II (large-scale wars produce increased consumption of fossil fuels for transportation. War-time explosions and fires also increase carbon-dioxide levels). The temperature curve rises again during the "globalization" of capitalism since roughly 1980. The upward curve of temperature increase, like that of carbon-dioxide content, is rising faster now than at any time since reliable world-wide records have been maintained. In fact, according to Houghton, "The rate of change is likely to be larger than the earth has seen at any time during the past 10,000 years." (p. 104)
          Human-generated carbon dioxide is produced mainly through the combustion of fossil fuels for electricity, heat, transportation and industrial processes. Houghton graphs global energy-usage levels over time in gigatons of oil equivalent consumed per year. During 1860, the start of his calculations, annual usage stood at about one-tenth of a gigaton per year. Between 1900 and 1940, energy consumption rose from roughly one to 1.5-2.0 gigatons a year. During the 1940s, usage began to increase more rapidly, passing 3.0 gigatons about 1960, 5.0 about 1970, and more than 8.0 gigatons by the late 1980s.
          Energy consumption is skewed widely by region. Energy usage per capita in 1990, according to a chart published by Houghton, (p. 190) is roughly five to six times as high north of the Rio Grande as in Latin America. Energy consumption per person in the United States is more than twice what it is in Europe, and roughly 15 times the amount used in sub-Saharan Africa. The largest factor in this difference is the pervasiveness in any given area of private automobiles and other motorized vehicles. (One also could plot carbon-dioxide levels and temperature against the proportion of the earth inhabited by indigenous peoples, extent of jungle and forests, as well as numbers of "wild" animals, and get similar results.)
          Having examined the evidence relating rising carbon-dioxide levels and temperatures, Houghton then speculates on what all of this means for the future of humankind. The prospects are not pretty.
          Since higher average temperatures would support greater levels of thermal energy in the atmosphere, Houghton and other scientists believe that atmospheric disturbances (storms) will tend to become more violent. The number of deaths related to storms (as well as costs of repairing damage) will increase, Houghton believes. Deaths from extreme heat also will increase, especially in large urban areas, Houghton writes.
          Houghton also believes that global warming will accelerate the spread of many diseases from the tropics to the temperate world, oftentimes spread by insects that thrive in warm climates. Malaria could increase from its present level of 350 million cases (and two million deaths) annually, Houghton warns. "Other diseases which are likely to spread for the same reason are yellow fever, dengue fever, and some viral encephalitis," he writes. (p. 132).
          Anecdotal evidence of global warming is available to any casual reader. Ice core records, for example, indicate that average temperatures on higher mountains in the tropics are higher than they have been in 2,000to 3,000 years. A piece of the Antarctic ice sheet the size of Rhode Island slid into the sea during 1995. Average temperatures in some areas of Antarctica have risen 4 to 5 degrees Celsius during the last fifty years. Tests indicate that arctic ice also is thinning at an alarmingly fast rate in geological time.
          According to NASA's Goddard Institute for Space Studies, the ten warmest years since reliable records have been kept on a global scale (roughly 1890) have occurred since 1980. Sea levels around the world have risen an average of four to ten inches during the last century, an amount that may seem small until one looks at it in terms of geologic time. The seas are rising faster than they have since the end of the last ice age, and stand at their highest level in 5,000 years.
          Not only are summers getting warmer on average, but humidity levels also are rising, making hot days and nights seem even more miserable. In the December 10, 1998 issue of the journal Nature, a team of scientists reported results from a thirty-year survey of temperature records across the United States. They found that the level of humidity is rising even more quickly than the temperature itself, especially during night-time hours.
          Houghton's book should be read in detail by anyone who still believes that global warming is a matter of whether or not. We have passed that point. Houghton, like a large majority of his scientific colleagues, agree that the evidence is incontrovertible. The question to which the avoidance is leading the public is: what is to be done, and, failing remedies on a global scale, what price is to be paid by future generations.
          Houghton does not attempt to answer how humankind as a whole will cope with the accelerating pace of global warming. In the meantime, some people -- in a few cases, whole nations of them -- are actively planning to reduce greenhouse emissions. Denmark, for example, is planning "farms" of skyscraper-sized windmills in the North and Baltic seas that, if plans materialize, will supply half the nation's electric power within thirty years. The Danish wind-energy manufacturers' association believes that electricity produced through wind power on a large scale will be financially competitive with power from plants burning fossil fuels, which will be phased out if wind power proves itself.
          Svend Auken, Denmark's environmental and energy minister, told the German magazine Der Spiegel that with half of his country's power coming from Norwegian hydroelectric plants and the other half from wind power, the country is planning to meet its electricity needs within three decades while reducing carbon-dioxide production to zero. The wind farms must prove their endurance in winter storms and stand up to the corrosion of seawater, but if they can, Denmark's windmills will prevent the production of 14 million tons of carbon dioxide a year, "our gift to the world," according to Auken.


Bruce E. Johansen, Robert T. Reilly Professor of Communication and Native American Studies at the University of Nebraska at Omaha, is author of Debating Democracy: The Iroquois Legacy of Freedom.