Back in the 1960s, the Cheonggyecheon (Cheonggye stream) which winds through downtown Seoul (South Korea) stood as an example of city planning going terribly wrong.

Following the end of the Korean War, massive numbers had flocked to the city and settled along the stream in shabby makeshift houses. Abused, it filled with trash, waste and sand and became lifeless. It was also covered with concrete from 1958. In 1976, a new elevated roadway spanning 16 metres above was completed.

Now, things have changed. Over two years beginning in 2003, the highway was ripped up and a 10.9-kilometre section of the stream was restored. Four species of fish inhabit the waters which previously had not been seen in the stream in 50 years. Birds and insects can navigate the city without difficulty. Summer temperatures at stream level are cooler compared with those above by five degrees Celsius. On weekends, families and children routinely congregate. Seoul, many commentators observed, had set the example to other Asian cities about going beyond an industrial mindset and making cities liveable for residents.

Speaking at the recent Green Cities conference hosted by the Green Building Council of Australia, Pascal Mittermaier, global managing director, cities at international conservation organisation The Nature Conservancy, says Cheonggyecheon in the 1960s was an example of attitudes at that time.

“You could have picked any city because this is representative of how we designed and built our cities over the last 100 years – asphalt, concrete, a heavy focus on cars and a ratio of cars to people between 10 and 50 to one,” Mittermaier said. “Yes, its Korea (in the 1960s), but I think we can recognise that there are elements of this in almost every city of the world that we go to today.”

According to Mittermaier, the consequences of such planning decisions are serious.

First, consider urban heat. The heat island effect kills more people in cities than any all other forms of natural disaster, Mittermaier says. One extreme heat wave in Paris in 2003 killed more than 15,000 people in 20 days. Look at maps of damage done, he says, and a direct correlation with how much nature and tree canopy existed in those neighbourhoods is evident.

Air pollution, as well, kills six million people every year. Tens of millions more suffer from asthma and other respiratory diseases.

Next, consider water. Cities drenched in asphalt and concrete, Mittermaier says, see water touch down on pavements before collecting and transferring pollutants into sewers, rivers and oceans.

Beyond direct impacts, there is a disconnect between people and nature. Across several countries, Mittermaier says children spend five to seven hours per day on devices but less than 30 minutes per week outdoors. In the US, some teenagers can identify more than 1,000 corporate brands but less than five native species. In one United Kingdom study which saw 20,000 people asked what it is like to put your hand in soil and have a caterpillar crawl across your skin, most city residents expressed fear and apprehension.

Apart from being harmful itself, this undermines future planning as those with little experience with nature growing up assume responsibility for decisions that impact cities and sustainability.

Mittermaier says there are several areas in which we can improve.

First, there is water. On this score, Mittermaier says rainwater gardens or ‘swales’ offer opportunities. The roots and soil from these capture, absorb and filter rainwater before it enters the stormwater system. As a result, these help not only to absorb water and protect from flooding but also to reduce the level of pollution in water which enters stormwater systems and ends up in rivers and oceans. They are also cheaper compared with designing and building underwater facilities with cisterns and pumps.

In the US, the City of Philadelphia has greened up 1,000 acres this way. Seattle has 20,000 such facilities – many of which are helping to prevent discharge into the inlet Puget Sound.

Where this becomes more exciting, Mittermaier says, is where this is combined with mapping technologies and planners map out entire cities. The small city of Bridgeport, about one hour north of New York City in Connecticut, has designed a series of green infrastructure projects to help stop polluted stormwater from flowing into the Long Island Sound. These also help form part of the City’s defences against storm water surges.

Next, there is air quality. Here, hairs on the leaves of trees filter fine particles and can deliver neighbourhood pollution reductions of between 20 to 50 per cent.

stormwater harvesting

On this score, Mittermaier says, the focus is not about planting millions of trees but targeting areas which deliver maximum return on investment. In a report last year, The Nature Conservancy looked at prevailing winds, density, traffic and other factors across 245 of the world’s biggest cities and mapped out where tree planting best made sense.

In Louisville, a five-year Green Hart project being undertaken by The University of Louisville in conjunction with others will see the planting of up to 8,000 trees, shrubs and plants where researchers feel they can best soak up lung damaging pollution. The ‘health response’ of 700 residents will be tracked and outcomes in ‘greened’ area will be compared against those in ‘non-greened’ ones.

In Melbourne, 32 councils are working to map out a biodiversity and urban forest strategy and understand impacts in terms of shade, air quality, equity and connecting people with nature.

Beyond specific projects, Mittermaier says it is important to connect young people with nature – especially in poorer and underserved communities where children are afforded few opportunities in this area.

Mittermaier says The Nature Conservancy follows young people with whom it works through high school. Significant numbers, he says, go on to follow paths in science or biology.

Beyond that, nature brings communities together. Showing one case of a project in a typical neighbourhood in Philadelphia, Mittermaier told the conference that more children are playing outside, parents are interacting with children, there is greater interest in food growing, more walking and cycling and greater interest in solar panels and energy efficiency.

Finally, Mittermaier says dialogue about nature can encourage focus on what is possible for our cities. He cites the example of Paris, which is talking about a vision of standing on top of Notre Dame, looking out toward the Eiffel Tower and seeing how nature can drive cities forward.

“Too many times, environmentalists talk about don’t fly, don’t eat meat, don’t wear leather,’” he says. “There is too much time spent on making things slightly less bad or avoiding them altogether.

“Nature is involved with all of the other trends: energy efficiency, driverless cars, driverless boats, people walking, cycling and growing food up and down buildings.

“This is a place where people want to live and work. It’s very different from describing how we are going to make things slightly less bad.”