To save our planet, we all need to co-inhabit the urban high rise instead of trying to reconnect with nature and hold on to some sort of misguided nostalgia from the past. Let me explain.

Urbanised societies, in which a high proportion of the population live in cities, developed during the nineteenth and twentieth centuries. Now, for the first time in human history more than 50% of the world’s population live in urban environments – and the peak is not yet in sight – by 2050 over 68% of the world’s population are expected to become urban dwellers.

In 1950, there were 86 cities with a population of over 1 million, this currently stands at 336 cities and by 2025 the UN expects this figure will rise to 735. In today’s world, ‘mega’ cities whose populations exceed 10 million people are the new metric. In 2025, projections for the world’s 40 mega cities are staggering. Mumbai is expected to have 26 million inhabitants; Shanghai 20 million and Karachi 19 million.

The infrastructure of our cities is not expanding fast enough to meet the needs of the people who are migrating to them. Current projections estimate that there will be three billion slum dwellers by 2050, representing a quarter of the world’s population. Across the world, birth rates in cities (1.6 children per couple) are far below the population replacement rates (2.2 children per couple). Cities may be the only effective form of contraception humans have invented to date.

As our population peaks over the coming thirty years, cities will become the core focal points of humanity and its civilisation. Cities are the key to a sustainable future and there are three areas we must focus upon.

Water: New York is one of the first global cities to secure a sustainable water supply, maintaining its watershed through land purchase and active management.

Whereas Sana’a in Yemen could be the first capital in living history to be abandoned due to a lack of water supply. Johannesburg faces issues over micro-bead and plastic contaminants polluting its drinking water supply that has and continues to affect its inhabitants.

Water is the primary resource that will ensure the resilience and survival of our cities. From water efficient washing machines to grey water management systems and leak detection and repair systems – the technologies exist to inhabit our cities more sustainably – but it requires ambitious political and social action.

Land: We cannot continue to use the fertile estuary plains on which most of our cities are built. We must build upwards not outwards. We must prevent the paving of our countryside for retail parks and roads and instead place electric high-speed public transport at the core of intercity connectivity.

We must seed our urban spaces, incorporate agricultural and natural spaces into our urban fabric and ‘green’ our cities so they become functioning social, environmental and ecological environments.

Power: Our cities typically consume 75% of the power we produce. If we were to switch to LED lighting in our major cities, we could eliminate the need for over 30 coal fired power stations in the US alone. New lateral urban wind farms should be integrated into the design of all our new cities. We must make power where we use it to reduce transmission inefficiencies and free up land to produce food.

Jeremy Clarkson has shown us that electric cars are as fast as any petrol driven equivalent. We must mandate non-combustion vehicles in all cities by 2025 and follow the lead of the German parliament that has called for a ban on internal combustion engines by 2030.

We should profit from the thermal energy beneath our cities to power them. The top 6km of the earth’s crust contains 50,000 times more energy than all the power contained in global coal and oil reserves.

Cities are our future, but our future looks bleak unless they become part of the solution to the problems our planet faces.

Whether it is Portland in Oregon, Malmo in Sweden, or the promise of sustainable Asian super cities– our urban ecosystems need to stop becoming net producers of waste and pollution and become contributors to water and energy security.

The future is fragmented but full of opportunity. Let’s get repairing it…