Australian Prime Minister Malcolm Turnbull recently encouraged the Centennial Park Trust and the NSW Environment Minister to seek National Heritage listing for this significant and popular Sydney park.

Writing on his own website, Turnbull said “A great city needs great parks. Unless they are set aside in the city’s youth, they are hard to retrofit after development has taken over. And once established they need to be jealously protected – as the city grows those green, open spaces are more precious than ever.”

I discussed the Prime Minister’s comments with my fellow AILA National Councillor Amalie Wright, whose interest in public parks has seen her visit, research and write about great city parks around the world.

We talked about the many things required to create and sustain great parks, and one overarching theme emerged: strong leadership. This has been the case for great parks in the past as well as new ones; it’s the case regardless of park size; and it is true whether the leadership comes from government or the community.

Community leadership helped save, promote and fund one of the most talked about parks in recent history, the High Line. Created above the streets of Manhattan on an abandoned, elevated railway, the High Line project was championed by local residents.

Robert Hammond and Joshua David met at a community meeting and went on to found Friends of the High Line, a not-for-profit organisation that was able to harness community interest in saving the structures from demolition, bring others on board to develop and illustrate the vision for an elevated park, use that vision to attract local patrons, and then to effectively advocate to local government.

Strong personal and community leadership has seen the High Line become one of New York’s most visited public parks, and taken Friends of the High Line from humble origins to become a powerful, not-for-profit conservancy that raises 98 per cent of the park’s annual budget.

Emscher Landschaftspark, in Germany’s Ruhr region, operates at a vastly different scale. Centring on an 80-kilometre long stretch of the Emscher River, this regional park was created following the collapse of the region’s coal exporting industry in the late-1980s. Nearly a century of heavy industry had dramatically altered and polluted the landscape, and the industry’s collapse resulted in skyrocketing unemployment and a bleak future.

A 10-year process was instigated to achieve ecological, economic and urban revitalisation. Everything from the industrial past was retained – hulking blast furnaces, smelters and refineries, towering slag heaps, sprawling mines – and the entire region was connected by a vast landscape park.

It was only possible through committed leadership.

Leaders from 20 regional cities and towns and two rural districts joined their federal counterparts to commit to a new, cross-regional, multi-layered planning culture.

More than 100 individual projects have been undertaken, the surrounding Ruhr metropolis is today one of the largest in Europe, and in 2010, the region was the European Capital of Culture, hosting 10.5 million visitors in the parks and landmarks of the Emscher Landschaftspark.

In Colombia, successive local administrations have championed the creation of new parks as part of a policy aimed at re-engaging the citizens of Medellin with their city after decades of violence.

During its time as the capital of the global cocaine industry, Medellin was reputed to have the highest per capita murder rate in the world. Over 500 police officers were killed, and fear kept people inside their homes, and out of the public spaces of the city.

When cartel boss Pablo Escobar was himself killed, the city started to turn a corner, but how to recover from that level of collective trauma?

Championed by the then-Mayor, and continued by his successors, the city instigated a programme of ‘social urbanism’ with a city-wide approach to public transport, education and more.

Amongst other things, Medellin began building public parks and plazas. They were all high quality, well designed, close to public transport, and paired with other pieces of public infrastructure – schools, libraries, and museums.

In Medellin, parks were not seen as the answer to all the city’s problems – no one thing could be – but strong local leadership recognised that parks and public places could help the community re-engage with, and reclaim their city.

We are lucky.

Australia does not face social, economic or environmental challenges anywhere near the scale of those experienced in Medellin or the Emscher region. But we do have challenges in our cities, towns and regions.

We do have members of our community who could benefit from the improvements to mental and physical health that parks provide, from the cleaner air and water that parks provide, and from the economic benefits that parks provide.

Those members of our community are us – we all benefit from great parks.

A significant and growing body of evidence supports the importance of access to parks and nature. Countless examples around the world also show that evidence and creative thinking are not the problem. We know why parks are good for us, what parks can do, and how they can help.

To really make a difference, parks need champions. If “a great city needs great parks” then great parks need great leaders.