All around the world, people flock from rural areas to the cities, eager to escape the grinding poverty of subsistence farming.

Kenya’s capital Nairobi is a case in point. This urban conglomeration - a local, regional and international economic hub - is seen as a land of greener pastures.

One of the first and most basic challenges for those who migrate to the cities is finding shelter. Most of the migrants have no choice but to move into one of the slums which are found both in and around Nairobi, such as Kibera, Mathare, and Mukuru. Jasper Onyancha moved to the capital from one of the rural areas in Kenya, hoping to find a better life.

'My names are Jasper Onynacha. I live in Kibera. I have a family, but they are staying in my rural area, that is in Kisii, in Nyanza province. I moved to Nairobi around one and a half years ago. When I decided to come to Nairobi, I did not know about Kibera. Basically, I wanted to look for a better life. That is why I came to Nairobi. I was trying to look for a place where I can actually feed (sustain myself), depending on my financial status...in Kibera slums that is where life is a bit cheaper.'

Population growth
The 2009 national census showed that the country had a population of 38.6 million people, with 3.1 million of them living in Nairobi.

David Kuria is the Chief Executive Officer of Ecotact, an environmental agency based in the city. David says there’s no doubt the growth of Nairobi's population has had a major impact on the country's climate and environment.

'Urban population growth rate is eight percent in cities in Kenya. The increase in population such as the move by people into slums increases a demand in consumption of manufactured products. This leads to an expansion of manufacturing industries, which increases emissions and has an impact on climate change.'

Mr Kuria’s remarks are being borne out by Jasper Onyancha’s observations of day-to-day life in Kibera:

“When people come here their financial status is low. That is why they have decided to stick in these places like the Kibera slums. Due to that they use various methods of cooking. They use firewood and other means of cooking and through my understanding that can cause air pollution which has got a big impact on climate change.'

Car pollution
David Kuria adds that as people seek to improve their economic status, they also start to consume more, and this too has an impact on climate change.

"The purchase of vehicles is one of the ways in which some of the people hope to change their status. Therefore the import of cheap second hand cars into the country is in great demand. These cars have low efficiency in terms of fuel combustion. This results in an increase of vehicle emissions which has an impact on the environment and climate. Every time you enter Nairobi nowadays you can see the impact of the vehicle pollution in the air."

Life in the metropolis has a negative knock-on effect on the surrounding countryside. The city keeps drawing in more and more water from surrounding areas to meet the needs of its ever-growing population. The resulting drop in the water table has led to the destruction of forests.

David Kuria says that trees and forests are essential in trying to cope with climate change, but little is being done to focus attention on the benefits of forest cover. And when it comes to tackling these very urgent problems, there have been but a few initiatives at the national level.

Kenya's Finance Ministry has presented a plan, but it focuses on carbon trading and the introduction of a system to sell carbon credits intended to tackle climate change at the international level. It would appear to be a positive step toward dealing with climate change on a global level. However, what - if any - effect this plan will have on the challenges posed by the ever increasing population of Nairobi, remains to be seen.

More on mega-cities in a special edition of RNW's Earth Beat programme