The issue of environmental survival is today no less critical than that of nuclear survival. The menace of the destruction of the ozone layer, the "greenhouse effect" and global warming are a very real threat to our every day existence and constitute the most troubling environmental predicaments of our time.

Man made pollutants emitted to the atmosphere are raising global temperatures to unprecedented levels. The United States and the Soviet Union are the world's biggest producers of carbon dioxide and fluorocarbons, gases that trap solar heat in a process called "the greenhouse effect." Over the last century atmospheric C02, the primary greenhouse gas, has increased by 25% mainly as a result of burning fossil fuels in power plants, factories and automobiles. World forest acreage has declined by 15% over this same period, with the rate of decline accelerating, particularly in South America. Deforestation removes vegetation that would otherwise draw C02 from the atmosphere, thus acting as natural thermostats.

If our present rate of fossil fuel consumption continues into the next century the amount of C02 and aerosols in the atmosphere will eventually reach a level at which a global temperature rise of 3 - 8OF becomes inevitable by the middle of the next century. Although this increase may appear insignificant it is enough to alter worldwide weather patterns, melt polar ice caps and flood coastal regions.

The most dramatic probable effect would be an unprecedented rise in sea level due to thermal expansion of the oceans and melting of glaciers and polar ice caps, including the world's largest ice reservoirs in Antarctica and Greenland. It is estimated that a 2-30F rise in global temperatures could result in a 5-7m rise in sea levels, and such populous metropolitan areas as New York, London, Shanghai, Tokyo and Rio de Janeiro will be partly inundated. In addition, the 50% of the world's population that inhabits coastal regions will be seriously affected.

Closer to home, large sections of Trinidad's west coast bordering the Gulf of Paria and including parts of Port of Spain and such residential areas as Westmoorings in the north and Gulf View in the south, may be at risk to the invading sea. Other islands such as the Seychelles and Maldives in the Indian Ocean may have to be abandoned altogether in 50 years time.

The anticipated rises in sea levels due to global warming could permanently inundate low lying coastal plains and wetlands (aesthetically unattractive, yet of considerable ecological significance), accelerate shoreline and beach erosion, increase the salinity of drinking water aquifers and biologically sensitive estuaries and increase the susceptibility of coastal properties to storm damage.

Forests may begin to die off in the next 10 years if they are unable to adjust to rapidly shifting climatic zones precipitated by global warming, thus compounding the problem. Parched soils, scorching droughts and intense heat waves associated with continental drying in middle latitudes could become a common occurrence. Other vagaries in weather patterns related to global warming include a possible reduction in rainfall in semi-arid regions and the likelihood of tropical humid climates becoming hotter and wetter, with tropical storms becoming more frequent and more severe. Floods which killed more than 90,000 people and affected at least 200 million more over the last 20 years, could worsen.

Some scientists believe that we are already experiencing climate disruptions caused by the greenhouse effect. Six of the 10 warmest years on record have occurred during the 1980s. Indeed global temperatures in 1988 were at or near the record for the period since instrumental data have been available, with temperatures somewhat elevated relative to the average for the 30-year period beginning in 1950.

Suggested remedial strategies to be implemented on a global scale include increasing energy efficiency and conservation to reduce the burning of fossil fuels, arresting the destruction of the world's forests and reforestation. However, although new cars today produce only 4% as much pollution as 1970 models, there are very little net gains since in most countries there are now 50% more cars on the road than in 1970, travelling more net miles. In the United States the Administration proposes that by 1997, 10% of new cars be powered by methanol, ethanol or compressed natural gas, fuels which are inherently lower in pollution than gasolene.

The crux of the problem is the ability to make more electricity to satisfy industrial and domestic needs from something other than fossil fuels. In this regard, and somewhat ironically, nuclear power plants, long considered a threat to the environment, may prove an environmental ally since nuclear plants produce I clean' energy and have no greenhouse effect.

Problems that take a long time to build up usually also take a long time to correct, and in terms of global warming the best that science can offer is a slowing up of the process. Since a lag of the order of several decades exists between emissions of greenhouse gases and their effects, the concentration of heat-absorbing chemicals already released into the atmosphere has irrevocably committed planet earth to an additional warming over the next 50 years, even if the atmosphere's composition were stabilized today. In other words, it is already too late to attempt to reverse the global warming trend, and we are bound to suffer some of the effects.