Appendix A Editorial Lancet April

819 Health in the Greenhouse result of man’s industrial activities, several changes are likely to occur in the global atmosphere in the coming decades. The magnitude of these changes is a function of the world population, the increasing demand for energy, and the burning of forests to free land for cultivation. The rate of change is the subject of much debate, the chief uncertainties being related to the ability of oceans to absorb carbon dioxide, the effect of increased cloud cover, and the destabilising effects of increasing moisture, melting ice caps, and ocean currents altering course.1 Most computer models predict a global temperature increase of between 1-5 and 4-5°C by the middle of the next century, with maximum changes occurring at the Poles.2 The impact on world ecosystems will be enormous, because world temperatures have changed by only 4°C since the last ice age. At the very least, there will be substantial shifts in biomass, food production, and the distribution of terrestrial species.3 At the worst, global ecosystems will be unable to adapt to a rapidly changing climate, world food production will collapse, and coastal areas will be inundated by rapidly rising sea levels. Such end-of-the-world sketches are familiar, usually in relation to AIDS or nuclear war, but there is an inevitability about global warming, which stems not from human behaviour or human error but from the radiative properties of atmospheric releases and the fundamental laws of physical science. As a The sun emits most of its energy between 0-2 and 4 pm, covering the ultraviolet, visible, and near infrared regions of the electromagnetic spectrum. 20% of this energy is absorbed by the atmosphere, 50% is absorbed by and warms the earth’s surface, and 30% is reflected back into spaced Because the earth is vastly colder than the sun, the energy emitted from the surface of the planet lies in the thermal infrared region of the electromagnetic spectrum (4-50 J.U11). Much of this energy is trapped by the earth’s atmosphere, by carbon dioxide and by water vapour, so raising the surface temperature of the earth from well below zero to about 13°C. In this context, warming of the lower atmosphere (troposphere) is not only beneficial but also essential for the maintenance of life on the planet. The greenhouse problem has emerged because carbon dioxide concentrations have risen from a pre-industrial level of 280 ppm to 350 ppm, and because other gases of anthropogenic origin are extremely efficient absorbers of thermal infrared radiation.5 Some of the chemicals that cause stratospheric ozone depletion---eg, chlorofluorocarbons (CFCs) 11, 12, and 113--can effect a warming more than 10 000 times greater than that produced by carbon dioxide on a molecule for molecule basis. their Because atmospheric concentrations are low, their overall greenhouse warming potential is less than that of carbon dioxide. Even so, without an international agreement to limit production, CFCs are predicted to increase the global warming effect of carbon dioxide by 50% in the year 2030.66 The contributions of other greenhouse gases, as a percentage of carbon dioxide warming, are methane 20%, nitrous oxide 14%, and tropospheric ozone 9%. Increasing methane levels result mainly from enteric fermentation in cattle and biological decay in wetland areas. Permafrost holds enormous quantities of methane which could be released by global warming with potentially catastrophic results.8 Nitrous oxide and tropospheric ozone are also derived from several sources, man-made contributions being related mainly to energy production and transport. Ozone is especially interesting because its formation in the lower atmosphere is a photochemical reaction whose rate will increase as stratospheric ozone declines. Thus, CFCs compound the greenhouse effect both directly and indirectly. Moreover, increased penetration of ultraviolet light into the surface of the oceans will adversely affect plankton populations and may interfere with an important sink for carbon 4. Shme K. The Greenhouse effect. In depletion-health and environmental Russell Jones R, Wigley T, consequences. Chichester. eds. Ozone John Wiley and Sons, 1989. 1. Broecker W. Unpleasant surprises m the greenhouse. Nature 1987; 328: 123-26. 2. Hansen J, Fung I, Lacis A, et al. Global climate changes as forecast by Goddard Institute for Space Studies three dimensional model. J Geophys Res 1988; 93: 9341-64. 3. Emanuel W, Scheugert H, Stephenson M Climatic change and the broad scale distribution of terrestrial ecosystem complexes. Climatic Change 1985; 7: 9-43. 5. Dickinson R, Cicerone R. Future global warming from atmospheric trace gases. Nature 1986; 319: 109-15. 6. Wigley T. Future CFC concentrations under the Montreal Protocol and their greenhouse-effect implications, Nature 1988, 335: 333-85. 7. Ramanathan V, Cicerone R, Smgh H, Kiehl J. Trace gas trends and their potential role m climate change. J Geophys Res 1985; 90: 5547-66. 8. Cicerone R Greenhouse effect-methane linked to warming Nature 1988, 334: 198. 820 dioxide.9 Finally, warming of the troposphere will be associated with a cooler stratosphere, so creating meteorological conditions ideal for the catalytic destruction of ozone. The rapidity with which ozone disappears each year in Antarctica has been attributed to increased formation of polar stratospheric clouds and the heterogeneous chemical reactions that take place on the surface of ice crystals. Nobody knows how widespread such processes might become; nobody really knows how much more chlorine loading the atmosphere can withstand. The only certainty among atmospheric physicists is that global warming and stratospheric ozone depletion will interact to destabilise the atmosphere in unpredictable ways, and that a total phase-out of CFCs is not merely desirable but an absolute and urgent requirement for any strategy to combat climatic change. Most scientists would like to see the Montreal protocol widened to include substitutes such as HCFC 22, since its desirability as a chemical with low ozonedepleting potential is offset by its potency as a greenhouse gas. If uncontrolled, HCFC 22 will be adding 15% to the global warming effect of carbon dioxide by the year 2030.4Similar, if less immediate, considerations apply to HFC 134a, industry’s favoured substitute for fridges and cooling systems, which could add 15 or 20% by the end of the next 4 century if emissions are uncontrolled.4 Whilst research into atmospheric chemistry continues, it is important to consider what might happen at ground level. Much has been written about the effects of stratospheric ozone depletion" but the implications for human health of global warming have received less attention. Temperature extremes will become more frequent and diseases caused by lack of sanitation will accompany widespread flooding.14 Global warming, increased ultraviolet flux, and higher levels of tropospheric ozone will reduce crop production, with potentially devastating effects on world food supplies.9°14 Malnutrition might then become commonplace, even among developed nations, and armed conflicts would be more likely as countries compete for a dwindling supply of natural resources. Diseases hitherto confmed to the tropics may spread to higher latitudes as global temperatures increase, and vector-borne diseases will become more widespread, either because the vector can survive at higher latitudes or because the parasite requires a minimum temperature to complete its life cycle. Malarial parasites, for example, require temperatures of at least 15-18°C to complete their development 9. Worrest R. Effects of ultraviolet-B radiation on terrestrial plants and marine organisms. In: Russell Jones R, Wigley T, eds. Ozone depletion—health and environmental consequences. Chichester. John Wiley and Sons, 1989 10. Environmental Protection Agency Assessing the nsks of trace gases that can modify the atmosphere. Washington, D C . US Environmental Protection Agency, 1987. 11. Russell Jones R Ozone deplenon and cancer risk. Lancet 1987, ii: 443-46. 12. Mackie R, Rycroft M Health and the ozone layer Br Med J 1988; 297: 369-70. 13. Russell Jones R. The health effects of stratospheric ozone depletion In Russell Jones R, Wiley T, eds. Ozone depletion-health and environmental consequences Chichester: John Wiley and Sons, 1989. mosquitoes. Temperature increases will lengthen the breeding season, and survival rates for the Anopheles species, flooding will provide areas of stagnant water ideal for breeding, and malaria could again become prevalent in European countries.14 A global analysis of all temperature-dependent diseases has yet to be undertaken, but in North America the US Environmental Protection Agency has pinpointed four vector-borne diseases, apart from malaria, that are predicted to increase in prevalence and extentLyme disease, Rocky Mountain spotted fever, dengue fever, and arbovirus-related encephalitis. Such changes in disease distribution are difficult to quantify with any certainty, but the message for decision makers is clear. Action to combat global warming must not be allowed to await the results of within further research. Remedial measures are needed now. Already this decade has produced six of the warmest years this century. Moreover, the lag effect as a result of the thermal inertia of oceans means that we are already committed to a further 0-5°C of warming, even if carbon dioxide is held at its present level. Any strategy to combat global warming must be conducted on a global scale and is bound to involve enormous investment in energy conservation, re-aforestation, renewable sources of energy, and changing patterns of agriculture and transportation. This approach will require a new agenda for world leaders, a new role for the United Nations Environment Programme, and a new awareness of man’s fundamental reliance on the integrity of world ecosystems. The expense may be considerable, but the cost of doing nothing is incalculable. Alternatives to Growth Hormone of human growth hormone (HGH) manufactured by recombinant DNA technology has led to renewed interest in the problems of children with short stature-at least three proceedings of symposia have been published in the past two years.1-3 Although HGH is now available in potentially unlimited quantities, exploration of alternative modes of therapy continues, not least because of the very high cost of biosynthetic HGH. All studies of growth hormone or of alternative agents are complicated by the considerable genetic THE availability 14. Grant L. Health effect 1 2 3 issues associated with regional and global air pollution problems. Paper presented to conference on The Changing Atmosphere— Implications for Global Security, Toronto, Canada, 1988 Flodh H, ed. Progress in clinical research on recombinant human growth hormones Acta Paediatr Scand 1987; 331 (suppl). Flodh H, ed. Diagnosis and treatment of impaired growth hormone secretion Acta Paediatr Scand 1987, 337 (suppl). Chatelain P, Gunnarson R, eds. Growth and growth disorders. Acta Paediatr Scand 1988; 343 (suppl).