Nations face three challenges in the modern world: to ensure the greatest welfare for their people; to make wise use of natural resources; and to do these things in such a way that they contribute to a solution that makes sense for the whole world. To face these challenges requires a high degree of international cooperation and a clear-thinking, unemotional approach.

Hitherto the bank of natural capital has been treated as though it were income; this is the antithesis of wisdom. In the future, natural resources should be used so as to get the greatest immediate benefit that is consistent with keeping open a range of choices and maintaining natural capital intact.

To be successful in this endeavour, ecological guidelines must be applied in the planning and use of natural resources. The depletion, or restoration, of natural capital, should be fully represented in calculations of costs and benefits, in order that what is good land-use is also seen to be profitable. Where the link between these two qualities is not evident, great political skill may be necessary in presenting proposals for the use or rehabilitation of natural resources. The final challenge is to reassess the values of societies and not to accept blindly those which have become customary—particularly if this has happened through their provision of short-term benefits.

Population explosions of the Crown-of-thorns Starfish, Acanthaster planci, first reported on reefs of the Great Barrier Reef in the Cairns region near lat. 17° S during the early 1960s, have since spread to numerous other reefs. The spread has been predominantly southwards, the principal region of infestation currently lying between lat. 19° S and lat. 19°20' S. South of this region, scattered infestations of reefs have recently been reported. Available data indicate that most reefs in the middle third of the Great Barrier Reef were infested during the last decade, and it is postulated that most reefs in the southernmost third will be infested during the next decade.

The bulk of the hard-coral cover of most of the inner platform reefs infested, and a lower but significant percentage of the hard-coral cover of the outer platform reefs affected by the infestations, have been devastated. Recovery of devastated reefs is in progress but is slow.

The A. planci infestations appear to the authors to be man-induced, and it is suggested that international action be taken to assess the magnitude of the A. planci problem and to coordinate possible control activities in the Indo-West Pacific region.

In the United States, the numbers of humans living on floodplains seem recently to have increased, and so probably have the annual costs of flood damage. This is despite expenditures of many millions of dollars on flood-control devices in the United States alone.

The means which we use to control or contain excessive water-energy are the dam, channel, levee, sea-wall, and floodplain management. Logic and evidence, although incomplete, seem to argue against employing only structures; indeed there now seems good reason to think that structures should rarely be employed for flood-control. The case against relying solely on a structural strategy to abate floods rests on four main arguments: it is often counter-productive in that it encourages human occupation of the floodplain, thus introducing the elements of future disaster that may be more serious than if nothing had been done; it causes severe and unnecessary losses of resources; it discourages the economic use of land; and it is not cost-effective.

Floodplain management, keeping the floodplain generally free from flood-control structures, is the only method which is effective in the long run. If it is planned adequately, its life is not as dependent on maintenance and upstream activity as are the structural alternatives. Moreover floodplains, when left undeveloped, are ideal and highly productive for a wide range of conservation and allied uses—including farming, parklands, open spaces, and habitats for wildlife.

The suggestion is made that Man evolved orthograde posture and bipedal locomotion at the fringe of tropical forest rather than in open savanna. The primary adaptive function of bipedal locomotion was for walking and stalking game from the cover of trees, in the absence of undergrowth. Hairlessness was thermally advantageous when Man emerged from the trees, yet would have imposed no great hardship on our hominid ancestors while they were inside the forest, where the climate was constantly warm. Man's primitive skin-colour was probably pale-brown. It is thought that dark skins were later acquired primarily as a protection against ultraviolet radiation in tropical regions, whereas depigmentation occurred as an adaptation that enhanced the synthesis of calciferol in regions of low light-intensity.

Man's so-called ‘racial’ adaptations occurred when his scavenging and hunter-gathering technology was unable to counter natural selection. Recently, however, he has ceased to respond to environmental feed-back. Unless he begins to do so again soon, degradation of the environment may accelerate beyond the point of no return and our species be doomed.

Although nature conservation may appear to be ‘wasteful’ to many people, it can only be truly described as such if one's sole purpose is mere survival for a short period of years. Longer time-horizons or other purposes require at least some level of nature conservation. The exact amount, in terms of land set aside mainly for this purpose, is difficult to determine precisely, but some general indications are given. Taking the world as a whole, it is concluded that something in the order of 20 per cent of each country should be devoted mainly to nature conservation (with countries having less than this amount contributing to the maintenance of reserves in countries with more than 20 per cent), if nature conservation is to be placed on an equal footing with alternative intensive forms of land-use.

During the period 6 December 1974 to 20 January 1975, the R/V Westward circumnavigated the Mediterranean Sea and took quantitative samples of pelagic tar at 48 stations. These have been compared with a similar survey made in 1969 by the R/V Atlantis II and with some data published in the USSR. In the ‘Ionian Sea’ (between Crete and the Strait of Sicily) the geometric mean of tar concentration has decreased significantly—from 60 mg/m2 in 1969 to 5 mg/m2 in 1974–75. In other regions of the Mediterranean, no significant changes were found. However, in both the ‘Tyrrhenian Sea’ west of Italy and the ‘Alboran Sea’ along the Algerian-Moroccan coast, tar concentrations have increased by about a factor of two, roughly corresponding to the relative increase in tanker traffic in the Mediterranean as a whole. In the ‘Balearic Sea’, 1975 levels were lower than those of 1969, but the data may not be comparable because of the different geographic regions covered.

At present, the total standing stock of pelagic tar in the Mediterranean is lower than in 1969, due to the decrease in pollution of the eastern basin. With the reopening of the Suez Canal, changes in the amounts of tar should be carefully monitored as a measure of pollution control effectiveness.

To circumvent the coming energy crisis the development of new sources is popularly associated with the gasification of coal and with atomic breeder reactors, although solar and nuclear fusion sources are distant possibilities. But coal is limited in supply and breeders will not be ready in time to replace the remaining oil and natural gas; wind offers a more likely possibility.

The practical equation for electricity obtained after conversion to hydrogen, passage, and reconversion to electricity, is:

for a rotor of 100 m radius in a location where the mean annual wind is v k.p.h. Thus, for v = 30, Pelec ≃ 5 MW per rotor.

The concept of large sea-borne rotors in high-velocity wind-belts with long-distance hydrogen transmission offers a more readily attainable (and more environmentally acceptable) prospect than atomic, or solar, possibilities.

Salt-gradient solar ponds function as systems to collect and store solar energy. The upper zone of the pond is rendered non-convective by the salt gradient and serves as a partially transparent insulator, permitting some of the incident solar energy to penetrate to the bottom and heat the lower zone to a temperature as high as 95°C. A pond 3 m deep and 150 m2 in area is expected to provide all of the winter heat required by a house of the same area in Columbus, Ohio.

Solar ponds occur in Nature. Research on artificial solar ponds was first begun in Israel in 1958 and some research has since been done in other countries. Recent results obtained by the author and collaborators indicate that solar ponds will be simple to operate and will provide low-temperature heat at a cost of perhaps $0.010 per kW-hr thermal. Experiments to obtain more definitive cost information are now in progress.