ice will torment truckers and automobile drivers; fewer winter storms — bad weather in the summer has less disruptive effects and is over quickly — will disrupt air travel; a lower incidence of storms and less fog will make water transport less risky. Hotter temperatures will leave mining and the extractive industries largely unaffected; they might even benefit oil drilling in the northern seas and mining in the mountains. Warmer weather means, if anything, fewer power outages and less frequent interruptions of wired communications. A warmer climate could, however, change the nature and location of tourism. Many ski resorts, for example, might face less reliably cold weather and shorter seasons. Warmer conditions would mean that fewer northerners would feel the need to vacation in Florida or the Caribbean. On the other hand, new tourist opportunities might develop in Alaska, northern Canada and other locales at higher latitudes or in upper elevations. A rise in world-wide temperatures will go virtually unnoticed by inhabitants of the advanced industrial countries. In his 1991 address to its members, the President of the American Economic Association asserted: "I conclude that in the United States, and probably Japan, Western Europe and other developed countries, the impact on economic output [of global warming] will be negligible and unlikely to be noticed."5 As modern societies have developed a larger industrial base and become more service oriented, they have grown less dependent on farming, thus boosting their immunity to temperature variations. Only if warmer weather caused more droughts or lowered agricultural output would even Third World countries suffer. Should the world warm, the hotter temperatures would enhance evaporation from the seas, producing more clouds and very likely more precipitation world-wide. Although some areas might become drier, others would become wetter. Judging from history, Western Europe would retain plentiful rainfall, while North Africa and the Sahara might gain moisture. The Midwest of the United States might suffer from less precipitation and become more suitable for cattle grazing than farming. On the other hand, the Southwest would likely become wetter and better for crops. A warmer climate would produce the greatest gain in temperatures at northern latitudes and much less change near the equator. Not only would this foster a longer growing season and open up new territory for farming but it would mitigate harsh weather. As a result of more evaporation from the oceans, a warmer climate should intensify cloudiness. More cloud cover will moderate daytime temperatures while acting at night as an insulating blanket to retain heat. The Intergovernmental Panel on Climate Change has found exactly this pattern both for the last 40 years, indeed for the whole of "Schelling [1992]): 6. the twentieth century. For the Northern Hemisphere in summer months, daytime high temperatures have actually fallen; but in the fall, winter and spring, both the maximum and especially the minimum temperatures (nighttime) have climbed. Warmer nighttime temperatures, particularly in the spring and fall, create longer growing seasons, which should enhance agricultural productivity. Moreover, the enrichment of the atmosphere with CO2 will fertilize plants and make for more vigorous growth. Agricultural economists studying the relationship of higher temperatures and additional CO2 to crop yields in Canada, Australia, Japan, northern Russia, Finland, and Iceland found not only that a warmer climate would push up yields, but also that the added boost from enriched CO2 would enhance output by 17 percent.? Researchers have attributed a burgeoning of forests in Europe to the increased CO2 and the fertilizing effect of nitrogen oxides.8 The United States Department of Agriculture in a cautious report reviewed the likely influence of global warming on crop production and world food prices. The study, which assumed that farmers fail to make any adjustment to mitigate the effects of warmer, wetter, or drier weather — such as substituting new varieties or alternative crops, increasing or decreasing irrigation—concludes that: The overall effect on the world and domestic economies would be small as reduced production in some areas would be balanced by gains in others, according to an economic model of the effects of climate change on world agricultural markets. The model... estimates a slight increase in world output and a decline in commodity prices under moderate climate change conditions." [Emphasis added.] Economists Robert Mendelsohn, William D. Nordhous, and Daigee Shaw researched the relationship of climate to land values in the United States.10 They concluded that for the lower-48 states, a rise in average temperature of about 5°F and an 8 percent increase in rainfall stemming from global warming would, depending on their model, reduce the value of output between 4 and 6 percent or boost the value of output slightly. This result ignored the boost of farm output from increased CO2. Forestry is another sector that is potentially subject to change due to an increase in world temperatures. Canadian agricultural economists have examined the effect of a doubling of CO2 on forestry production. They concluded that increased carbon dioxide "Folland et al. [1992]Climate Change 1992, Table C2, p. 152. 7Parry et al. [1988] as summarized in Kane [1991]: 7. 8Kauppi, et al. [1992]: 70-74. 9Kane et al. [1991] 10 Mendelsohn,[1994]: 753-771. would boost productivity by 20 percent and that overall the harvest of timber in Canada would climb by about 7.5 percent.11 Past Climate and Human Well-being Since statistics on the human condition are unavailable except for the most recent centuries, I have used indirect methods to demonstrate the influence of climate on man's well-being. A growth in the population, major construction projects, a significant expansion in arts and culture, all indicate that society is prosperous. If the population is expanding, food must be plentiful, disease cannot be overwhelming, and living standards must be satisfactory. In addition, if building, art, science, and literature are vigorous, the civilization must be producing enough goods and services to provide a surplus available for such activities. Renaissance Florence was rich; Shakespeare flourished in prosperous London; wealthy Vienna provided a welcome venue for Haydn, Schubert, Mozart, and Beethoven. Clearly climate is far from the only influence on man's well-being. Governments that extort too much from their people impoverish their countries. A free open economy stimulates growth and prosperity. War and diseases can prove catastrophic. On the other hand, a change in climate has frequently been a cause of war or aided the spread of disease. A shift to more arid conditions, for example, impelled the Mongols to desert their traditional lands to invade richer areas. A cold wet climate can also confine people to close quarters, which can abet contagion. Moreover, a shift towards a poorer climate can lead to hunger and famine, which make disease more virulent. The influence of climate on human activities has declined with the growth in wealth and resources. Primitive man and hunter-gatherer tribes were at the mercy of the weather, as are societies which are still almost totally bound to the soil. A series of bad years can be devastating. If, as was the usual case until very recently, transportation is costly and slow, even a regionalized drought or an excess of rain can lead to disaster, although crops may be plentiful a short distance away. Thus variation in the weather for early man had a more profound influence on his life and death than do fluctuations in temperature or rainfall in modern times when economies are more developed. Since the time of the Industrial Revolution, climate has basically been confined to a minor role in human activity. History since the Last Ice Age The last Ice Age ended about 12,000 to 10,000 years ago when the glaciers covering much of North America, Scandinavia and northern Asia began to retreat to 11Van Kooten [1990]: 704. approximately their current positions. In North America the glacial covering lasted longer than in Eurasia because of topographic features that delayed the warming. Throughout history warming and cooling in different regions of the world have not been exactly correlated because of the influence of oceans, mountains, prevailing winds, and numerous other factors. Nevertheless, across the Northern Hemisphere large temperature shifts have occurred roughly together — perhaps in some areas they have lagged other zones by a century or more. Human progress, a few improvements in hunting tools and some cave art, was incredibly slow during the Ice Age a period whose length dwarfs the centuries since. Over the last 12 millennia of interglacial warmth, however, modern man has advanced rapidly. The growth in technology and living standards required a climate that was more hospitable than existed throughout that frozen period. As the earth warmed with the waning of the Ice Age, the sea level rose as much as 300 feet; hunters in Europe roamed through modern Norway; agriculture developed in the Middle East. For about 3,000 to 4,000 years the globe enjoyed what historians of climate call the Climatic Optimum period - a time when average world temperatures · at least in the Northern Hemisphere were significantly hotter than today, about 4° to 5° Fahrenheit warmer than the twentieth century.12 During the relatively short period since the end of glaciation the climate has experienced periods of stability separated by "abrupt transition."13 During the Mini Ice Age, the temperature in central England for January was about 4.5°F colder than today. 14 In the central and northern latitudes of Europe during the warmest periods, rainfall may have been 10 to 15 percent greater than now and during the coldest periods of the Mini Ice Ages, 5 to 15 percent less. 15 On the other hand, cooler periods usually suffered from more swampy conditions because of less evaporation. If modern humans originated 200,000 years ago, why did they not develop agriculture for the first 190,000 years? Even if Homo Sapiens Sapiens originated only 40,000 years ago, people waited 30,000 years to grow their first crops an innovation which yielded a more reliable and ample food supply. Farming developed first in the Middle East, right after the end of the last Ice Age a coincidence? The evidence suggests that from 11,000 to 9,000 years ago the climate became warmer and wetter in the Middle East shifting the ecology from steppe to open woodland. 16 This led to the domestication of plants and animals, probably because the warmer, wetter weather made farming possible. Although many people view the current world's huge population with alarm, most ecologists take the size of the population of a species as an indicator of its fitness. By this criterion, the domestication of plants and animals improved greatly Homo Sapiens fitness. This testimony is not the place to discuss the capacity of the globe to sustain the number of people expected to populate the world in the next century, but certainly anything that produced greater numbers of people thousands of years ago must have been beneficial for mankind. Over history the number of humans has been expanding at ever more rapid rates. Around 25,000 years ago, the world's population may have measured only about 3 million. 17 Fifteen thousand years later, around 10,000 B.C., the total had grown by onethird to 4 million. It took 5,000 more years to jump one more million, but in the 1,000 years after 5000 B.C. it added another million. Except for a few disastrous periods, the number of men, women and children has mounted with increasing rapidity. Only in the last few decades of the twentieth century has the escalation slowed. Certainly there have been good times when man did better and poor times when people suffered — although in most cases these were regional problems. However, as the following chart shows, in propitious periods, that is, when the climate was warm, the population swelled faster than during less clement eras. This chart is based on a paper by economist Michael Kremer who argues that, until the Industrial Revolution, existing technology limited the size of the population.18 As innovators discovered new techniques and invented new tools, more people could be fed and housed and the population expanded. Moreover, the greater the number of people, the more innovations would be hit upon. He assumed that every individual had an equal but very small probability of uncovering a new technique or device and that the probability of being an innovator was independent of the size of the population. Therefore the number of inventions would be proportional to the number of people. Thus as the world population expanded slowly at first the rate of technological innovation escalated and hence the rate of growth of the population that could be sustained. Only in recent times has technological change become so rapid that it has run ahead of population growth, leading to a rising standard of living, which in turn has reduced the birth rate. 17Kremer [1993]: 683. 18Kremer [1993]: 681-716. |