THE world is edging closer to overpopulation Armageddon as swelling cities drain the planet of its vital resources, a report warns Wednesday. Population growth, especially in newly developing countries, is the 'defining challenge of the 21st century. It represents a greater potential threat than climate change, according to the Institution of Mechanical Engineers. Over the next six decades the worlds population is expected to explode, soaring from 6.9billion to peak at 9.5billion in 2075, the report says. Each year the number of people in the world is due to rise by 75million - equivalent to the entire population of the UK. Most of the growth will be in the African continent, which is following in the industrial footsteps of Asia, and in cities. The worlds urban population is likely to increase from a 2007 figure of 3.3billion to 6.4billion in 2050. But without drastic changes there will not be sufficient resources to provide people with basic human needs such as water, food, energy and shelter, says the report, entitled Population: One Planet, Too Many People? Climate change is likely to place even more stress on resources, resulting in as many as a billion people moving from inhospitable regions. Water requirements are projected to rise by 30 per cent by 2030 while food resources will be stretched by a doubling of demand for agricultural produce by 2050. Slum living, already forced on a third of the worlds urban populations, will become even more widespread as cities became increasingly packed with people. As a result billions could be at risk of hunger, thirst and appalling living conditions, creating tinderbox conditions that could ignite civil unrest and conflict. The report, compiled with the help of more than 70 engineers around the world, sets out a series of 'engineering development goals as a first step towards averting the looming disaster. It calls for a global engineering initiative, modelled on the United Nations Millennium Development Goals, to tackle the key problem areas of energy, water, food, urbanisation and finance. Lead author Dr Tim Fox said: 'Towards the end of the century the world is going to come face to face with the challenges of the largest population explosion in human history. 'These headline figures really are staggering from a resources point of view and for the provision of the basic needs of human society. Engineering solutions such as reducing energy waste, improving food storage and extracting water from underground aquifers would allow the world to sustain a population of 9.5billion, said Dr Fox. The cost would run into many trillions of pounds, but would be affordable if richer nations were willing to share financial as well as technological resources. A key necessity is to help poorer nations 'leapfrog the resource-hungry 'dirty phase of industrialisation. As population levels soar in newly emerging industrialised countries, those in developed parts of the world such as the UK and US are likely to stabilise or even fall, said the report. The population of Europe is expected to decline by 20 per cent by 2050. However, the impact of global population growth would still be felt around an increasingly connected world where changes in one region could have an impact 'many thousands of miles away. Daily Mail