"The power set free from the atom has changed everything, except our ways of thinking." So said Einstein. Whether or not he foresaw the total destruction of the world, the thought gave rise to a joke, albeit a sick one, that humans would never make contact with civilizations in other parts of the universe. Either those civilizations were not advanced enough to decode our signals or they were more advanced than us, had developed nuclear weapons and had destroyed themselves. The chances would be vanishingly small that their brief window of time between technological competence and oblivion would coincide with ours.
I never understood the policy of deterrence that justified the nuclear arms race. The coherence of such a view depended utterly on the maintenance of human rationality. Suppose that people whose concern for personal safety or thought for others was subordinated to religious or ideological belief ruled a country in possession of nuclear weapons. The whole notion of deterrence collapses.
I usually regard myself as an optimist. Tomorrow will be better than to-day. My naïve confidence has been dented by advancing age and by the growing number of reality checks that point to trouble ahead. Even if the red mists of anger or insanity do not unleash the total destruction of our way of life, the prognosis for the survival of human civilization is not good. However much we believe in technical fixes that will overcome the problems of diminishing resources, the planet is likely to be overwhelmed by the sheer number of people who inhabit it and by the conceit that economic growth for everybody is the only route to well-being. The uncontrolled greed of the developed world has taken a sharp knock in the recent credit crunch, but how do you persuade affluent people to accept an overall reduction in their standard of living? Which government of any stripe is going to risk its future by enforcing the unpopular policies that are already needed? On this front the prognosis might not be too bad since crises do bring about change.
The Yom Kippur war of 1973 led to a dramatic reduction in the oil supply and, in the UK, petrol rationing was swiftly introduced and everybody was required to save fuel by driving no more than 50 mph. The restraint disappeared, of course, as soon as the oil started to flow again, but the experience showed that people will uncomplainingly change their behavior when they are required to do so and understand the justification.
Growth of the human population must be one of the major threats to sustainability of resources such as drinking water and food. Here again the prognosis does not have to be wholly bad if far-sighted wisdom prevailed. If the GDP of each country of the world is plotted on graph paper against average family size in that country, the correlation is almost perfectly negative. (The outliers provided by rich countries with large average family sizes are almost exclusively those places in which women are treated badly.) The evidence suggests that if we wished to take steps to reduce population growth, every effort should be made to boost the GDP of the poorest countries of the world. This is an example were economic growth in some countries and overall benefit to the world could proceed hand in hand, but the richest countries would have to pay the price.
Another darker thought is that human population might be curbed by its own stupidity and cupidity. I am not now thinking of conflict but of the way in which endocrine disruptors are poured unchecked into the environment. Suddenly males might be feminized by the countless number of artificial products that simulate the action of female hormone. Sufficiently so that reproduction becomes impossible. For some the irony would be delicious. The ultimate feed-back mechanism, unforeseen by Malthus, that places a limit on the growth of the human population.
Sustainability is the goal that we pass onto the next generation the resources (or some equivalent) that we received from our forbears. It may be a pipe dream, given the way we think.