Today, October 31, has been designated by the United Nations as the day on which the world's population reaches 7 billion. That figure arrives amid revised projections for the future which could see the population of the planet reach 9.3 billion at 2050 and more than 10 billion by century's end.
If this is a sobering prospect, the United Nations Population Fund (UNFPA) says in a report to coincide with the occasion that "with only a small variation in fertility, particularly in the most populous countries, the total could be higher: 10.6 billion people could be living on Earth by 2050 and more than 15 billion in 2100".
While on the one hand UNFPA points to the fact that such a milestone can be regarded as a success for mankind - with greater prosperity and better education meaning that people are living longer and healthier lives - the world's burgeoning population also poses considerable challenges to the future wellbeing of the planet and the species.
Urgent among these are food shortage and environmental damage; as the population continues to balloon, the demand for food increases at a great rate. Already about 1 billion people on the globe remain hungry, and supplying food for them from increasingly marginal land threatens to speed up the rate of environmental damage being wrought on the Earth by the demands made of its resources.
High among these are water and arable land. Water, particularly in poorer areas of the planet, South Asia, much of Africa and Central America, can be a critical factor in determining peace and stability: in already drought-prone areas, scientists and population experts are predicting future wars for access to and control of this most precious and life-sustaining of resources.
Likewise arable land: large tracts are already being bought up in Africa by Chinese interests for example. These are being tilled and planted or prepared for food production evidently to insure against the almost inevitable food shortages in a future more populous world. Semi-arable land is also being brought into production, straining water resources and contributing to desertification.
Climate changes is intertwined with all these challenges: water scarcity, food insecurity, migration, conflict over resources, the strength and frequency of natural disasters, all of which, if unchecked, can be allowed to portray a particularly gloomy scenario for the future of humankind.
The scenario of a world populated by 15 billion by the year 2100 is certainly one to concentrate the mind and there are strategies for dealing with the issues such totals raise. One of the first is to acknowledge that we live on a resource-constrained planet and that growth - of population and resource-dependent economies - cannot carry on indefinitely and perpetually. Then it is a matter of deploying and spreading technological innovation, education, contraception, women's rights, so as to begin to reverse the population growth trend - while at the same time addressing the world's other pressing problems.
Energy generation and use ties in with all this too; the scaling of peak oil only heightens and hastens the need to develop cheaper and more sustainable sources. Entrepreneurship, government policy, educational programmes to engender in the population an ever greater awareness of the need to conserve, or place greater value on, natural resources, can all help.
Seven billion is a vast number of people. In 1959, it was 3 billion. In the decades since the 1950s, better food production and distribution, education, medical advances and communication technologies have all played a part in helping to raise the average world life expectancy from 48 years to about 68.
This is, indeed, cause for celebration and optimism: the problems that man faces can be addressed; solutions can be found. What is required, though, is the will to face the issues and to work in concert on the answers. That will by and large requires political leadership; it also requires the facility and the generosity of spirit to look beyond narrow sector or national interests.
It requires vision, commitment and determination. How the world and its leaders choose to respond to the challenges posed by the 7 billion milestone reached today is the real significance of the occasion.
