Biophysical and other ‘outer limits’ of food, land, water, climatic change, stratospheric chemistry, energy, hazardous substances, non-fuel minerals, human stress, and social and ecological stability, raise fundamental questions about present trends in management methods and in global organization. The diverse outer limits surveyed in this paper reflect complex, poorly perceived, and often unsuspected, interconnections between numerous biological and geophysical processes, many of which are obscure or still unknown. Our lack of predictive power, let alone of quantitative understanding, implies a need to treat essential life-support systems with great caution and forbearance, lest we erode safety margins whose importance we do not yet appreciate.

Even those outer limits which now seem remote are relevant to present policy, as their timely avoidance may require us to discard otherwise attractive short-term policies in favour of others that offer less immediate advantage but that retain options which may be needed later. Such alternative policies may have to rely more on social than on technical innovation in order to address underlying disequilibria rather than merely palliating their symptoms. Moreover, some outer limits are sufficiently imminent, or require such long lead-times to avoid, that fundamental changes in policy, in institutions, and in the degree of global interdependence, seem necessary if we are to live to enjoy some of the later and more interesting limits to human activity.

Solar energy could be a major resource for the semiarid regions of the United States and the world. This source of energy is a popular topic in the media at this time, but is it really the option which many would like to see or is it more likely to remain the illusion it has been up to now? Many ways of using solar energy have been proposed, and each appears to have a good technological basis. The additional factors that will see many solar schemes fall by the wayside are the hard facts of economics and the realities of social assimilation of technological advances.

The major options of house-heating and cooling and electrical power production need to be examined. Home uses depend upon the degree to which people are willing to put up with the inconveniences associated with bulky roof-top units. It is more likely that solar energy will subsequently find wider acceptance when it can be converted into power and transportable fuels at remote solar power-farms located in the arid regions of the United States and other lands that are fortunate enough to have these sunny regions. The savings to the environment could be very considerable.

My contribution to the crusade for the perpetuation of all life on Earth, indeed for the very tools for survival if the situation becomes more critical, has been the opportunity to put the case for conservation of Nature and natural resources over to the public in general, and also to present it to the great decision-makers of our time—the men and women who have such mighty power for good or evil, and on whose vision and actions the future of Man depends. I have been able to do this because of the dedicated support I have received from my colleagues in the World Wildlife Fund (WWF), and from our sister organization and scientific adviser, the International Union for Conservation of Nature and Natural Resources (IUCN), all working in close partnership.

A new and promising field has appeared as a result of the increased tourist industry based on natural resources, though too often such expansion has been achieved without due planning and has taken many people by surprise. Conservationists and their organizations have often reacted adversely to this ‘invasion’, but this need not be so. There are many reasons and examples which prove that a change of attitude, leading to a symbiotic relationship between tourism and conservation in the wide sense, can offer a very large variety of advantages and benefits—physical, cultural, ethical, and economic—to a country.

A tourist industry can expect a brilliant future, based on natural assets of the environment, provided due consideration is given to the ecological principles which must guide resource-use. The alliance of those responsible for tourism with ecologists and conservationists is a natural one, that should contribute greatly to development—the right kind of development involving the right kind of change—leading to a better quality of life for all concerned.

A brief description is given of the physiography, climate, and natural vegetation, of Iran. Subsequently an analysis is made of the environmental problems which are building up to crisis proportions. Of particular concern is the alteration and destruction of natural ecosystems through the impact of Man over a period of many centuries. As a result of H. I. M. the Shahanshah's personal attention to this problem, forests were nationalized, range improvement measures have been instigated, and the Department of the Environment has undertaken a comprehensive programme of conservation and management of areas of national importance.

A programme of scientific investigation and management of wildlife resources has been initiated. Intensive studies of Wild Sheep, gazelles, and Persian Ibex, are now under way. In all reserves the condition of the vegetation is closely monitored. Due to these measures, wildlife populations have increased in most reserves. Iran has some of the finest wetlands in south-west Asia, and has made much progress towards their preservation, over one million hectares of the most important wetlands being now fully protected.

The Department of the Environment has had considerable success in its programme of protection of endangered species—including the Onager, the Persian Fallow Deer, the Asiatic Black Bear, the Asiatic Cheetah, the Marsh Crocodile, the Great Bustard, and the Caucasian Black Grouse. The future of these species is now almost certainly ensured in national reserves.

Iran now has four categories of reserves: National Parks, Protected Areas, Wildlife Refuges, and National Nature Monuments. Thirteen National Parks have recently been approved. Currently there are 27 Wildlife Refuges. An extension of this network of national reserves is planned within an international framework.

It is conventionally argued that a stable ecosystem, namely one with high species-diversity and high constancy in physical parameters, is less sensitive to additional stress than a system with varying physical parameters and low species-diversity. By this logic, the Baltic would be more susceptible to additional stress, such as that of pollution, than the North Sea.

Examples of irreparable damage to some of the most stable ecosystems in the world, such as coral reefs and tropical rain-forests, suggest, on the contrary, that these systems are more vulnerable than low-diversity ecosystems, such as a brackish-water zone in the mouth of a river or a coniferous forest in a temperate region.

Studies of stress tolerance in estuaries showed that the species already living under stress, such as that of reduced and changing salinities, were more tolerant to pollution than species in a less fluctuating environment. This adaptability to environmental changes seems to be characteristic of ecosystems with a low degree of individual specialization and high genetic diversity (i.e. a large number of alleles). Following this conclusion, we question the underlying assumptions in the statement that for example the Baltic Sea, which can be regarded as a large estuary, is an area particularly susceptible to stress; purely marine ecosystems are probably more sensitive.

Ecosystem stress-tolerance should be made a top priority in ecological research; this is a necessity inter alia for future localization of industries, in order to minimize their effects on the environment.

Investigations conducted along the west coast of Florida from Tampa to Cape Sable have shown that mangroves are confined to the upper portion of the intertidal zone by the wood-boring isopod, Sphaeroma terebrans Bate. As a result of this activity, mangroves are unable to become established throughout the intertidal zone and to extend shorelines in their usual manner.

The attack on mangroves is most severe from Marco to Cape Sable, and is probably the single most important factor responsible for the erosion that is currently occurring along this section of coastline. Throughout its length, tides, temperature, and salinity, appear to influence the severity of the attack on mangroves by S. terebrans.

Mangrove-dominated estuaries from Tampa to Cape Sable serve as nursery areas and feeding grounds for several commercially important marine fishes and Crustacea. The continual loss of mangroves as a result of S. terebrans activity, erosion, and human interference, may well decrease the extent to which these vital estuaries can be used as nurseries by commercially important species.

The current environmental pollution problems created by burning and dumping agricultural residues, together with concern for the conservation of future forest resources, have engendered interest in finding utilization outlets in building-board manufacture for the large amounts of crop residues that are produced annually. Experimental boards were made from corncobs, corn-stalks (Zea mays), peanut-hulls (Arachis hypogaed), sunflower seed-hulls (Helianthus annuus), and spent instant coffee-grounds (Coffea arabica). In general, most of the residues alone, and mixtures of either a wood waste and a crop residue or two different crop residues, produced composite boards having properties comparable with or better than those of boards made from conventional wood materials. However, boards made from spent coffee-grounds or sunflower seed-hulls can only be used as vertical, installed decorative items.

The utilization of crop residues for the production of useful board products will not only provide an acceptable disposal method for those who produce the residues, but will also reduce pressures on future forest resources. In looking to the future, it seems clear that the reasons for improving the environment and for extending the future wood supply, will soon outweigh the objection to using crop residues for board production which involve high collecting and handling costs.

The Environment Protection Act of the State of Victoria appears to be working. It has very sharp teeth, so that offenders face imprisonment or heavy fines (or both) for breaches of its terms. Furthermore, industries face the alternative of either complying or closing down.

On the other hand, the rather extreme demands of those who would almost deny Man a role as part of Nature at all, nevertheless perform a very useful function in drawing attention to threats to the environment. Any inroads on present wilderness areas are rightly being publicized and debated, and should be firmly resisted in the interests of Man himself wherever in a practical sense this can be done. Vegetation is widely recognized as essential to keep the levels of harmful elements under control. Forested wilderness, as we know, removes from the atmosphere a great deal of carbon dioxide and, by the photosynthetic activity of the green leaves, turns it into carbohydrates and wood, thus sequestering it and giving out oxygen in exchange.

The oceans also absorb carbon dioxide and so retain carbon in their depths. However, the increasing concentration of carbon dioxide in the air leads to a gradual warming of the oceans, so that they can hold less. One of the major problems to be faced is that increasing industrial activity is discharging increasing amounts of carbon dioxide into the atmosphere and impairing the capacity of the biosphere to redress the balance.

Victoria is a small State in a large world. It is attempting to tackle pollution within its borders by drawing upon the experience of others throughout the world who have faced the same difficulties in an aggravated form. However, it is felt by those working within the Act that it may represent an advance over most legislative systems of control. The politics of pollution involve compromises at most levels and also the setting of priorities within financial possibilities to effect controls. Whether the target date of 1980 or thereabouts in respect of control of river systems can be attained, like that of 1982 for cleaning up Port Phillip Bay to a desirable standard, remains to be seen. Such items depend on governmental funding as well as the acceptance, on the part of the community, of the necessity for the protection envisaged. Meanwhile it is gratifying to note that industry has responded in an admirable way and realistically recognizes that the very expensive changes to plant and factory which the licence scheme requires must be implemented in the public interest.

Those members of the community who have little or no financial stake in any enterprise that is affected by the activity complained of, regard the Act as a step in the right direction—providing, as it does, a public forum for them to air their views as of right. However, their complaint usually is that the Act does not go far enough, and they would restrict industrial development to the very minimum. They provide a necessary correction and balance against the more immoderate demands of those who believe in technological development—whether it involves the unrestricted use of supersonic transport aircraft, the mining of uranium, or the unlimited proliferation of factories discharging wastes into air and/or water.

Within the framework of the Act and the interplay of opposing points of view, the government of the day can only thereby become better informed and enabled to reach acceptable political decisions. The approach of establishing uses of the environment which are beneficial to humans should, in the long run, preserve for posterity all that is best in the environment having regard to its ability to absorb wastes without detriment to such beneficial uses. Finally, some instances of trade-union intervention are narrated as pertinent.