‘What we do or do not do in cities will have a decisive effect on future temperatures’

Ms Rossbach, we see slums in many cities in the Global South, as well as a lack of housing in the Global North. Is housing a worldwide challenge?

It certainly is. Up to 3.4 billion people are living in inadequate conditions — that’s almost 40 per cent of the world’s population. More than 1.1 billion of them live in informal settlements and slums, more than 300 million are homeless, and many millions are displaced. While it may seem that the bulk of the problem occurs in the Global South, housing is also a significant issue in the Global North. Most large cities in industrialised countries suffer from a shortage of living space, making it increasingly unaffordable for many people. So, wherever we look, we see housing challenges.

How can the world build more and better housing without contributing to climate change?

This is a very good question, and I would argue the other way around – that better housing helps us deal with climate change, instead of contributing to it. The urban poor are the most affected by the housing shortage and climate change impacts alike. When we build proper housing, with sustainability and resilience in mind, people can be housed and protected from extreme weather events.

Different approaches are needed in different parts of the world. In the Global North, a lot can be achieved by upgrading, regenerating and transforming exisiting buildings, making use of empty spaces, and densities, overall making cities more compact. We see a different picture in the Global South where cities are still growing and expanding at enormous rates. It is expected that around two billion people will move to urban areas in Asia and Africa alone by 2050. There is no doubt that more housing is needed. However, building more houses is not enough. We need systemic changes and solid urban planning.
 

What should such planning include?

Above all, urban planners must ensure that land use does not grow faster than the population, as is currently the case. Urban sprawl is accelerating and has to be managed. We also need to recognise the social and ecological functions of land. What we need are well-thought out, planned quarters with green spaces and sponging techniques. The latter involves absorbing, storing and slowly releasing rainwater rather than allowing it to run off into drains immediately.

Why is that important?

It has a cooling effect and helps to reduce urban flooding and recharges groundwater, making cities more resilient to heavy rainfall in general. Such measures are particularly important for the poorest and most vulnerable members of urban populations because they suffer the most from climate change. For instance, we know that during heat waves, the temperature in informal settlements can be much higher than in other areas. In Rio de Janeiro, for example, the difference can be up to eight degrees Celsius, according to community-led research.

In summary, what are the three most important measures, in your view, to make cities more climate-resilient?

Transforming informal settlements is at the top. This is a matter of human decency, but it also helps cities to adapt to climate change and to stop uncontrolled sprawl into nature. Secondly, there needs to be good planning in place to meet the growing demand for housing. Thirdly, cities need many more green spaces and urban water elements. The three measures are connected.

Talking of sustainable cities: Copenhagen and Amsterdam come immediately to mind. Which cities in the Global South would you mention as good practice?

Medellín in Colombia is a classic case of transforming informal settlements, using urban mobility as a social tool for urban integration, and building green corridors to reduce heat. Rio de Janeiro is strengthening the green infrastructure in its informal settlements, with multilevel approaches that engage the community, city, state, and national level. UN-Habitat is working with the Rio de Janeiro State Government to develop local climate action plans with the cities in the state of Rio de Janeiro, building capacity in the process. We can also find good examples in small and medium-sized municipalities. Morondava, in Madagascar, is restoring its mangrove ecosystem by training local youth communities. This reduces the risk of floods, storm surges, and improves drainage.

We can think of many other examples. Nairobi is progressing with its Rivers Basin Regeneration Programme. Quezon City in the Philippines is focusing on disaster risk reduction in its land use plan, besides making the city more compact so that its population has access to urban services without traveling far from its major transport routes. Or take Curitiba and São Paulo, where urban mobility is advancing its public fleet with electric vehicles. There are many examples of cities making a big effort here.

Is it true that the battle against climate change will be won or lost in cities?

Definitely. Cities are already responsible for up to 70 per cent of emissions, with now about 58 per cent of the world’s population living in urban areas. This figure is expected to rise to around two thirds by the middle of the century. Therefore, what we do or do not do in cities will have a decisive effect on future temperatures.

Cities are also the level of government closer to the territory. Global commitments such as the Paris Agreement are delivered to the people by mayors and city halls. Cities need to be empowered to deliver climate action, having access to the resources needed to fight climate change and improve the life of their citizens.

Is the role of cities in climate protection widely recognised?

Yes, recognition has grown significantly in recent years. A recent UN-Habitat study shows that 80 per cent of national climate plans – the Nationally Determined Contributions (NDCs) – include strong commitments on climate action in cities.

The challenge now is implementation. Only 19 per cent of these countries have committed to increasing subnational climate finance. That tells us that political recognition of cities is increasingly being matched by ambition but not yet by investment. Closing that gap will be one of the defining challenges in the years ahead.

How can we channel more funds to cities?

We need to establish partnerships between local and national governments. Mayors cannot solve the problem alone. They must obtain funding from other sources. For instance, the responsibility of setting up housing finance mechanisms is up to national governments. In turn, local authorities must ensure that new housing is built sustainably and really benefits the people, including the poorest, by providing access to basic services and sufficient green spaces.

How much money is needed to make cities climate-resilient?

Cities require around 4.5 trillion US dollars in investment per year through 2030 to implement climate solutions. This includes transport, energy, water, waste and communications, as well as adaptation measures. Today, investment stands at around US$831 billion per year. But that’s nowhere near enough. Urban climate finance would need to increase more than fivefold to meet the investment levels required under the Paris Agreement.