With the twin challenges of climate change and population pressure working in tandem, isn't it time we fundamentally reassessed our relationship with our cities?
There is overwhelming agreement among members of the scientific community about the risks posed by climate change to the environment and to population centres, and that there is a need mitigate these risks.
Cities around the world are feeling the effects of extreme weather events such as tropical cyclones, unprecedented heatwaves and droughts. And modelling indicates that the frequency and intensity of extreme weather events will escalate in decades to come.
Multiple lines of evidence exist to show that our climate system is changing. Consider that in Australia alone, each decade has been warmer than the previous decade since the 1950s, and there has been an observable decrease in cold days and an increase in warm days (with more than double the number of record hot days) since 1960.
As for global sea levels, they have risen at an average rate of 1.8mm per year between 1961 and 2003, and rose precipitously to 3.2mm per year from 1993 to 2012.
While Australia may not face the same kind of existential threat that rising sea levels pose to some of our Pacific neighbours, the fact remains that our country is a predominantly coastal society. With approximately 85 per cent of the population inhabiting the nation’s periphery, any significant rise in sea levels will result in increased frequency of extreme sea level events such as storm surges that have the potential to impact swathes of the population. Nor is the risk confined to Australia’s coastal regions. A rise in sea levels will increase the likelihood of flooding along estuaries, rivers, lakes and lagoons in inland areas, too.
With the population of Australia’s major cities growing rapidly – Sydney alone is projected to have 8 million inhabitants in just over 40 years' time – it’s a truism that climate change and the trend towards denser urban living will act to multiply risk.
Experts in urbanism and sustainable development indicate that there are ways to mitigate that risk to ensure our cities remain liveable, sustainable and safe. However, these may not be the ways that we’ve comfortably considered implementing before.
Is it time to revisit the rule book about urban planning and design? And what can we learn from cities that have taken meaningful steps towards addressing the challenges facing us all?
Liberty OneSteel spoke with Dr Rob Roggema, Professor of Sustainable Urban Environments at the University of Technology Sydney, and an expert in climate adaptation, renewable energy and urban agriculture, to get a glimpse into the future as to how urban design will adapt to our changing environment to create adaptable and resilient cities.
Q: How are climate change and population growth impacting one another?
A: The two trends are connected very closely with one another. Climate change is happening everywhere, but because the bulk of the world’s population lives in cities, this is where we’re seeing the combination have the greatest impact.
About 70 per cent of the world’s population lives close to the coastline – and we’ve seen the devastating effect that an extreme weather event can have on population centres with the hurricanes that have hit [the Caribbean and] the United States recently.
So, we have a couple of trends happening. Global warming will continue even if we are to stop our emissions overnight. And at the same time more people are coming to the coast and living in concentrated urban areas. In effect, the two trends are having a multiplier effect in terms of the risk they present to large population centres.
Q: Assuming we continue on our present path, what will we see more of?
Countries in the South Pacific are definitely susceptible to the impact of rising oceans – Bangladesh is one country that comes to mind. But even a place like New York is vulnerable.
In our part of the world, one interesting thing we’ll see more of is cyclones headed southward as a result of the oceans heating up. A city like Sydney, for example, starts to be at risk not only of heavy storms, but also cyclones. Sydney hasn’t been hit by a cyclone before, but my prediction is that it will within a couple of decades.
Sydney, and other population centres such as Canberra, will also become more susceptible to hotter days, drought and bushfires. My prediction for next summer will be that Penrith [in Sydney’s west] will hit 50 degrees, which will have an obvious impact on energy consumption and energy bills, not to mention the effect it will have on people’s health and wellbeing.
Q: What is sustainable urbanism and what does it mean for the resilience of cities?
Sustainable urbanism is a very broad term, but it basically encompasses efforts to make cities more liveable and that encourage the health of all the organisms that make up the urban ecosystem. It means considering the flow of materials that come into the city and go around the city, such as water, energy and nutrients.
The stronger an ecosystem is, the more resilient the whole system is. If we diminish or minimise it, then our ability to provide a healthy and sustainable urban environment is compromised. Thinking about our cities means thinking about our urban ecosystems in an integrated and functional way.
For example, our water systems need to have space so that dirty water can be converted into clean water, renewable energy sources can be prioritised, and all our food needs can be met.
Q: How should we redesign our cities to encourage resilience and counter the effects of extreme weather events?
Adaptability or the ability to manage change is deeply embedded in resilient cities and is lacking in those cities that aren’t resilient. When a city can change functions, change users, change building sizes or street patterns – and can do so quickly – you have a city that can adapt very easily.
Let me give you an example. We use a lot of concrete in our cities, which has two effects: it increases flash flooding within cities (because natural absorption is impacted); and it creates an urban heat island effect (as the concrete rapidly absorbs and slowly radiates heat energy), which means cities are made hotter and more uncomfortable for its residents.
Perhaps we should consider ‘unplanned’ or temporary space to help promote adaptability? It can be a space where water goes when there is flood, where it’s green when it’s too hot, where something temporary can happen. For instance, a roof can have different functions – it can be a garden or it can comprise solar panels. How about we put a 40cm levee around the edge of every roof to form a basin, so it can also act as a reservoir when it rains? That way we can ensure rainfall peaks don’t end up in the street.
On a larger scale, playgrounds or squares can turn into water basins. In the event of rain, these basins can fill up with water and be used productively. Once the rain is gone, the water can be released slowly, like squeezing water from a sponge.
Q: What role can buildings play in allowing our cities a defence against the effects of climate change?
Buildings, at the planning stage, should be designed in such a way that they aren’t fixed. We should start to consider what I call ‘demountable cities’. In the way that you can take a book from a bookshelf and put it back or you put it somewhere else, at a building level you can do the same. We haven’t seen it applied yet, but it can be done.
Imagine making buildings that are footloose, that aren’t constructed in the ground, but can be demounted so they can be moved to another place.
We always have 2–3 days warning that a hurricane is about to hit. Could we rearrange the buildings in a city in such a way that they shield the city from a hurricane, or they create spaces that wind can channel through? That kind of flexibility is what we need. It may sound like science fiction, but the buildings we construct now can’t do that – they stand where they stand.
Q: You have researched how to engineer a natural defence against future storms in the form of a ‘Sydney Barrier Reef’. Tell me more about that.
There is a threat posed to the urbanised coastal areas of Newcastle, Sydney and Wollongong by the warming of the southern Pacific Ocean. I suggest we consider a ‘Double Defence’ of the coastline by establishing an artificial reef 30km off the coast, where the Pacific plateau is actually pretty shallow.
The foundations can be concrete, steel or wooden structures just below the water’s surface and designed to act as a base for new coral growth. This artificial reef can help protect against storm surges hitting the coast, eroding beaches and washing away buildings near the ocean’s edge. It can also mitigate storm surges entering the Parramatta River and flooding low-lying areas along the peninsulas.
We need to think big if we’re to protect against future threats posed by ocean warming.
Q: Where to next with your research?
I feel like a lot of the thinking in the area of urban resilience is still within comfortable confines. I want to advance the question: are we doing things fast enough? My preliminary answer is ‘no’.
Instead of doing things incrementally, we need to make a jump. We need to bring radical urbanism into our planning. If I speak to a large builders or planners, I find that everyone is still in their existing collaboration type. It’s so difficult to jump out of confined ways of thinking, but we now need to look at issues facing us now in a completely different way.
Whether it’s where we bring our food in from, or how we’re talking about water or energy supply, or how we’re dealing with climate change, we need to consider more radical solutions than we have previously.
Photo: UNSW Water Research Laboratory