Over the last century the world's population has more-or-less quadrupled. If the trend continues then by the year 2109 the world's population will be about 28 billion! Moreover, due to "global meltdown", the latest forecasts by glaciologists say, that "by the turn of the present century, sea levels are likely to rise by about 7 m (23 ft)". Thus, we have two concomitant problems over the next 50 years or so, namely, a growing world population and shrinking dry land. Now some 71% of the Earth's surface is covered by water; only about 29% is covered by dry land. Therefore to increase our area of "dry land" on Planet Earth, I suggest that we build floating island cities & floating island farms. In the case of the latter, I suggest that we use the hydroponic method of agriculture, where to grow our crops, we require sunlight, water , air & nutrients; we do not require soil. For both types of floating island, I suggest that we use 'green energy', namely wave energy, tidal energy, wind energy, solar energy and bio-mass energy, where in the case of the last, we use human waste as a fuel for power stations.
For a BBC radio broadcast on this topic, Click:
http://www.dailymotion.com/video/xats5q_radiosolentbroadcast15102009
For a newspaper article on this topic, Click:
http://www.portsmouth.co.uk/newshome/Portsmouth-professor-shortlisted-for-award.5735259.jp