By 2050, 70% of the world’s population will live in cities. Projections show that urbanisation combined with the overall growth of the world population could add another 2.5bn people to the urban population by 2050.
This poses a challenge for urban planners.
On the one hand, modern cities need to continue to create jobs, homes and social infrastructure to handle a growing influx of residents. On the other hand, planning constraints and rules typically date from the post-war period, when pollution and the scars of war encouraged the growth of suburbia as residents retreated from city centres.
One issue illustrates this tension more than any other: the green belt, enshrined in the 1947 Town and Country Planning Act. So is a policy that dates from the time of the second world war still appropriate?
The debate has become polarised. There is a clear conflict between those wanting a blanket loosening of green belt policies to foster economic growth, and those who feel extra protections for green space are needed to counter the impact of urbanisation and protect rural land.
In Birmingham we have found ourselves in the middle of this debate. The need to release land to meet the housing and economic needs of the city was compelling, but there was also strong local opposition.
The experience has shown us that there is a possible third option: it is time to reassess what land is categorised within the green belt.
Recent criticism of the green belt policy has focused on the issue of housing. The argument goes that the policy limits land supply and therefore housebuilding rates. As a result, it encourages house price inflation, unsustainable commuting patterns and, ultimately, inequality.
This argument is valid, but not sufficient. The problem of meeting housing need runs far deeper than just land supply: under-occupancy of homes, questions about the right mix of tenures, density and the rights and wrongs of council housebuilding are also highly relevant.
By contrast, others see green belt policy as a great success story, arguing that it has supported urban renaissance by focusing development within urban areas, restricting sprawl and safeguarding the countryside.
This argument is also valid, but again insufficient. The green belt has played a critical role in limiting sprawl, but structural economic changes have been important. The shift to high value service and creative industries that rely on a clustered workforce and connectivity has been the key driver of urban renaissance.
But what if we could shift the debate from centralised discussions of national legal frameworks, to local discussions about how individual areas should be categorised?
By distinguishing between high quality and low quality green belt land, and facilitating land swaps where necessary, it should be possible not only to free up appropriate land for development, but maintain strong protection for valuable community assets. In Birmingham our housing and economic need would have justified a larger release than was secured, but it would have been inappropriate given the high quality of the green belt sites that were viable.
My hope is that such an approach, based on local knowledge and understanding, could be developed more widely. Enabling a comprehensive reassessment of green belt areas, delivered at a local level by housing market area, should ensure that the positive impacts of green belt policy are maintained, while ensuring new development is more sustainable both economically and environmentally.
This approach will no doubt be tough to deliver politically.
However, the pressure on our urban space is only set to continue. This is the type of difficult decision which cannot be avoided if we are to manage that pressure effectively. A comprehensive reassessment of the quality of green belt areas should ensure that the policy continues to be a positive force shaping planning and urban development for many years to come.
