In the first of a six part series investigating the growing gap between food production and global population growth, DJ Clark explains the key issues facing Asia and how they have arisen. Over the next five weeks DJ will be travelling across the continent to discover how this looming food shortage will affect the poorest communities and to meet the innovators who seek to find solutions. In part two he will be reporting from Asia's most food insecure district, just across the Chinese border in Nepal's western hills.