There’s an interesting little stat in the FT today. If the whole world population lived at the same density as Hong Kong we’d all fit into an area the size of Egypt.

Now of course that might bring it’s own problems but if you look at the trends, it might not be crazily unrealistic. The world’s urban population was 54% of the total in 2015 and the global rate of urbanisation is currently estimated at 2.05% per year (says the CIA). If that continues, the percentage land area occupied by humans looks set to decrease considerably over the next 30 years. We could see total depopulation of many rural areas in our lifetimes.

We’ve got a lot of work to do to create the tools that will help us live sustainably in cities. Whether it’s aquaponics, lab meat or vertical farming it looks to me like we’ll need to become less dependent on rural food production. We’ll also need new solutions to housing, transport and democracy that are able to cope with higher levels of density.

When I think about it, it’s one of those mega-trends that creeps up on you over decades but is driving so much of the way that things are changing.