The number of people that the world can support with food, water and energy is estimated at four billion. There are currently seven billion people. In August every year we pass the point where the world is self supporting - after that we a borrowing resources from future generations, our children, grand children and their descendants. This debt will have to be paid back.
The driving force behind all environmental problems, global warming, pollution of air and water, sea level rise, desertification,loss of resources, water and energy scarcity, for example, is overpopulation.
If the government of the UK were to declare concern or, better still, a policy on the population of the UK it would be a good example and set down a marker for other countries around the world to follow.