10/02/2013 14:20 GMT | Updated 12/04/2013 06:12 BST

The Injustice of Overpopulation

A few weeks ago, a coalition of charities launched the Enough Food For Everyone IF campaign. Its ambition is to eliminate global hunger. It names the four issues which it believes to be the keystones of this ambition: Aid, Tax, Land and Transparency. But I was astonished that there was absolutely no mention of something equally, if not even more, important: overpopulation.

The global human population now numbers 7 billion and, even if our growth is now slowing as some believe, we are heading for disaster. All around the world the costs of our success are evident: to name but a few, forest cover is shrinking by 13 million hectare per year, numerous fish species have experienced total collapse, and climate change looms.

Much environmental degradation could be lessened if we were to rein in our overconsumption. North America and West Europe are responsible for 60 percent of private consumption spending while overall, global human demand exceeds what the Earth can give - currently we're using 1 and a half planet's worth of resources per year. It might become 2 planets' worth by 2030 if current population trends continue.

Most population growth is happening in the developing world. The clue is in the name - many developing nations are on their way up, both in terms of economics and population, and their citizens understandably aspire to the lifestyle we already enjoy in the developed world. But the environmental problems that the world faces won't be remedied simply by addressing overconsumption. Similar to how our increasing use of electronics easily offsets their improving efficiency, 'greening' the way we use the planet's resources will achieve little when more and more people require them.

I'm sure many people tuned in to the last episode of Africa a few nights ago. David Attenborough used the episode to give us some frightening facts: Africa's population is currently around the 1 billion mark, and is growing at double the global rate, a trend expected to continue. Africa is a vast continent, but as a result of human pressures it is steadily losing natural resources like forests. 90% of its people are dependent on wood for their main energy source. Even if commercial logging and agriculture were somehow reduced in scope, the needs of the burgeoning population would still have to be accommodated. But the damaging of ecosystems always incurs costs. There is growing scientific evidence that rainforests generate rain, even as far as affecting the global climate, while it is accepted knowledge that vegetation prevents soil erosion and thus the spread of desert and wasteland. Combined with climate change, Africa may well be facing a future of droughts and, ultimately, human suffering on a scale we've not yet seen.

Endeavouring to curb population growth can only be a positive thing. Many of the actions we could take are intrinsically humanitarian in themselves. Improving access to education and family planning for women encourages them to have fewer children and gives them more control over their own lives. Preventing death from causes like malaria and starvation fosters a sense of assurance that parents do not need to have large families to ensure that at least some of their children make it to adulthood (this is where the IF campaign could fit in perfectly - if only it would make overpopulation one of its 'issues'). In a similar vein, stable states with functioning welfare systems reduce the incentive for parents to have large families as a means of ensuring that they will be cared for in old age. For some countries, these 'soft' actions might have to be bolstered by legal limits on reproduction. Such limits may result in social dysfunctions, as with sex-selective abortion in China . But they may turn out to be the lesser evil.

Which of the following paths is more feasible? To persuade people in developed countries to give up much of what they take for granted, or to persuade everyone to have less children? We must choose at least one of these if we don't want to be pulled down the third path: population crash. Such a fate has been forecast before and seemingly averted; the 'Green Revolution' of the mid 20th century ushered in methods of intensive farming that have kept the world fed since (well, some of the world). But the cost has been the proliferation of fertiliser which leaches into the oceans and damages our food sources there; antibiotics which encourage the evolution of disease; and the continued removal of the forests and vegetation which hold soil together, keep back deserts, and produce much of the rain and waterways which people across the globe depend on.

The WorldWatch Institute writes "the world's poorest will need to increase their level of consumption if they are to lead lives of dignity and opportunity". If we truly want to see a world where social and environmental justice are realised together, we must all change.