Today we're looking at urban migration, the movement of people migrating from outside cities into cities.
I think it's easy to jump to the conclusion that a rural lifestyle is greener.
However, recent studies have suggested otherwise.
First of all, if we take the land area of the earth, the proportion that cities take up is a mere 3%, and these same cities actually produce 30 to 40% of the carbon that is released into the atmosphere, a lower amount than the 60 to 70% from non-urban areas.
Anyway, let's imagine that most people decide to migrate to the city.
What kind of impact would that have?
For a start, this movement of people from the countryside should lift the pressure of intensive agriculture from the land, allowing forests to regenerate.
Another point in favour of urban migration is that it can be far more energy efficient if services are concentrated in the city, for example.
This is true for electricity and, as you can imagine, water.
Then, once you remember that rural communities are often very spread out, you can see yet another green reason to live in the city.
Rural citizens rely on the car to make their journeys far more than city dwellers who have other more environmentally friendly forms of transport that they can use, such as buses and trains.
The journeys tend to be shorter too.
Yet another point in favour of urban migration is the kind of recycling schemes that can only take place where the population is concentrated.
Take, for instance, Seattle in the USA, where methane gas is being put to good use and is generating energy for the city.
It's produced from the city's rubbish, which could not be collected so efficiently from rural areas.
Now, another factor that threatens the environment is the growing world population.
It's estimated that 75 million babies are now born every year and in some countries the birth rate shows no signs of slowing down.
Urban migration may provide an answer here.
Now, in cities, one of the reasons that women tend to have fewer children is that they get married later and start their families later.
And the reason for this is that it's far easier to find a job, and once you have one, to get a promotion.
So, yes, the focus isn't on bearing children.
Well, it would be foolish to pretend that there are no downsides to urban living when clearly there are.
The thing that critics often mention is the idea that migrants may end up losing their culture, although some studies have found the opposite is true.
Rather than give up their traditions, people actually work hard to maintain them.
More evident is the fact that, compared to the lower rate that is observed in rural areas, we can see that there is more crime occurring in cities.
There won't be many of us here today who can say we haven't been directly or indirectly affected by it.
There's another issue that we have to deal with.
So many cities, including our own, now suffer from high levels of pollution so that the air we breathe is far from pure.
And another factor against the urban is greener idea is that urbanisation often drives a country's economy.
Put simply, when there is greater wealth in society, more energy is consumed.
One of the direct effects of a stronger economy, something that many citizens will now experience every day and may well find stressful, is the amount of traffic on the road, despite the other options we mentioned earlier.
This is a problem that is not about to go away, although there are some solutions that could be considered.
Let's have a look at some of those.
