Introduction (draft and first part)
Rutherford (2004) gives us the number that eighty percent of the American population are now living in metropolitan regions. Worldwide we have a number of half the world’s population living in cities. And more will come. If we take a closer look at the largest cities "mega cities" some of them like Mexico City have grown from 2.9 million to 22.1 million from 1950 to 2004, Jakarta from 1.5 to 16.0, Istanbul 1.1 to 11.1 meaning growing 10 times in around 50 years, some even more extreme is Seoul-Injon that have grown from 1.0 to 21.9 and Dhaka 40 times from 0.4 to 15.9 (Planet of slums, but there is a homepage...). Mumbai is estimated to grown to 33 million to 2025 (2.9 million in 1950 and 19.1 million people in 2004) and to be the largest city in the world, even if it’s not sure its biologically or ecologically sustainable (Planet of slums, but there is a investigation). When people are moving there so fast the cities is not prepared for it and slums will be the result. One of five people in the cities in the world are living in the slums. There is a need to do something for the cities.

Rutherford, R.H., 2004. Regreening the Metropolis: Pathway to more ecological cities. New York Academy of Sciences, 1023, p.49-61