As extreme weather becomes commonplace, the Darwin Living Lab evaluates what cities in the tropics can do to stay cool enough to be liveable.
Temperatures in Darwin can easily reach above 30°C all year round and are predicted to rise because of climate change. The capital of Australia’s Northern Territory sits comfortably in the wet-dry tropical zone, characterised by an eight-month dry spell followed by four months of intense humidity and monsoon rains. Any heat mitigation measures must account for very different conditions.
In 2021, the City of Darwin, Northern Territory Government, and the Australian Government teamed up to publish the Feeling Cooler in Darwin: Darwin Heat Mitigation and Adaptation Strategy. This action plan lays out aspirations for a science-first approach, using a variety of Nature-based Solutions, shade, and material treatments to make this tropical city feel cooler and a more liveable, attractive place to be.
Darwin as a Living Lab
The strategy was written in collaboration with the Darwin Living Lab (DLL), a project that came out of the Darwin City Deal, a 10-year urban improvement plan backed by $200 million of capital investment.
This opened the door to a number of heat mitigation measures being trialled around Darwin’s inner city precincts, measured and evaluated by CSIRO, Australia’s national science agency, scientific lead in the DLL, and trusted advisor to authorities at all scales.
Stephen Cook, a CSIRO researcher with an interest in urban climate adaptation, tells us that the role of Darwin Living Lab is to provide decision-makers with the science they need to make informed decisions on Darwin’s future.
“It’s not particularly groundbreaking science to say you’ll be cooler under a tree,” Stephen jokes, even though it’s undeniable. But data gained from piloting cooling solutions can tell cities the specifics, which reveal how they can maximise efforts by evidencing what kind and height of trees provide the most effective shade, where’s best to plant them, and whether there are any better alternatives.
And although CSIRO is running the show, DLL includes a fair amount of citizen science; it brings together stakeholders from research, industry, government, and communities to help determine what their need are, where the hotspots can be found, and what kind of impact the trials are having.
What’s the Matter with Heat Anyway?
We as a species still haven’t fully grasped the magnitude of extreme heat.
The new normal of rising temperatures is deadly, having killed more than 1,000 Australians in just three years.
Heat stress affects people differently, with vulnerable groups most at risk, including children and the elderly, pregnant people, those with preexisting medical conditions, and homeless communities. Outdoor workers are also dangerously exposed. Health and social implications cost the country $8.7 billion annually.
Darwin has problems of its own. The population topped around just 160,000 in early 2026, as people from the Northern Territory are tempted away to cities further south where the climates are more tolerable. This population turnover has consequences for the “vibrancy of the city,” Stephen explains, adding a further challenge to attracting and retaining (working) people and Darwin’s economic growth.
Hot Source
The question is, why is Darwin so hot?
As a tropical city, it was always going to be a scorcher, but the nature of its built environment exacerbates heat stress.
Our CityChanger explains that “large expanses of dark bitumen car parks” trap the heat, creating an urban heat island effect, where the city is hotter than the land around it.
The City Plan acknowledges that this can push surface temperatures of unshaded roads to a dizzying 67 degrees Celsius in the middle of the day.
This is typically when people take their lunchbreak and want to move between offices and eateries and stores and services, but the oppressive heat prevents it or endangers their wellbeing if they do. Stephen observes that outdoor benches exposed to the sun remain unused.
The University of New South Wales carried out thermal imaging and drone aerial monitoring for the Northern Territory Government, which revealed a “big river of red running through the middle of the city”.
Because of this buildup of heat, it hardly cools, making nights deeply uncomfortable too. It gets really risky in times of heightened humidity, as our bodies’ natural defence to the heat – sweating – is less effective.
For those who can afford it, air conditioning offers some relief, but this doesn’t tally with Darwin’s designs on reducing one of the highest energy consumption rates in the country. Plus, air-con only works indoors. Real ambient cooling is needed citywide.
Totally Tropical Solutions
As 2025 drew to a close, the Darwin Living Lab project was about halfway done. Its decade-long timescale gives scientists the chance to measure change and impact over an extended period to identify long-lasting solutions.
Stephen details some of the initiatives in place so far.
Water: Nature’s Coolant
The DLL is currently trialling the role of water misters in cafes and other outdoor venues around the city. Water vapour is prayed into the air, helping diners cool down, and it seems to be enjoyed by playful children to boot. It’s effective in the immediate area, so businesses nearby can offer al fresco dining, although it has less impact in and leading up to the humid wet season.
In the near future, locals will be provided with evidence of when misters or just a fan should be used to keep them cool – the latter working through increased air movement.
A Transport Trade-off
Given that asphalt is such a heat trap, Darwin dedicated some of its $37 million upgrade of the central State Square precinct to replacing many of the open air car parks. Vegetation and water features put in their place “reduce heat generation and provide a vibrant, tropical, green open space for public gatherings and events,” handing more space back to people, Stephen explains.
It also aligns with the City of Darwin’s objective to create cool travel routes in an attempt to increase active and micro-mobility transport by making moving about the city more comfortable.
Provision from the various former car parks were consolidated into an underground multistorey, which doubles up as a shelter in extreme weather incidents. Elsewhere in the city, roadside parking spaces were altered to make room for greenery, but not actually removed. “There might even have been a net gain by changing the angle,” Stephen suggests.
Reflective Surfaces
Artificial surfaces can be improved and still serve familiar functions. Darwin is trialling pavements made of material that reflects rather than absorbs the sun’s direct heat, to prevent it from contributing to urban heat island effect,
This keeps the ground – and the air directly around it – cooler; rolled out across the city, this could result in lower average temperatures. But unshaded reflective pavements have been found by DLL to “create quite hostile environments for pedestrians” because “the radiant heat is reflecting back up” on them instead.
Green Canopy
Maybe the answer is to filter some of the heat before it hits these surfaces.
This idea was tested on Cavenagh Street where a 55m-long shade structure was erected above reflective surfacing to test the multiplier effect of combining these ideas.
Rangoon Creeper and Orange Trumpet vines were planted at the base in the hope that they would grow over the frame to create a natural shady canopy and improve “people’s experience in the city” and also their wellbeing.
Building shade structures with climbing plants can be an efficient way to provide that green link between areas.
Unfortunately, the ivy didn’t establish well, leading to criticism for what some public opinion saw as a wasteful expense.
“Yeah, that was a somewhat contentious topic in the community, because it’s in a very prominent place in Darwin,” and because of the costs associated with maintaining the structure, our CityChanger reflects. The amount of shade wasn’t so much the issue, but the overegged expectations: “Visualisations at the start had this very verdant canopy and then people would go along and see this vine that was struggling to cover the shade structure.”
A Degree of Success
Efforts to cool the city have paid off, though.
“Shading from trees and greenery has been shown to lower the surface temperature of streets and pavements by between 10 and 23 degrees,” the Darwin City Deal states. Stephen highlights that removing radiant heat through shading also improves thermal comfort by up to 5 °C, potentially eliminating heat stress completely.
And the DLL has made significant advances in how cities can approach the challenges present in tropical cities.
“One of the most powerful,” he explains, has been to capture “a very a high resolution [picture of] land cover change”.
By recording the evolution of canopy cover “down to the level of an individual tree” and cross-referencing this with the Australian Bureau of Statistics census data, DLL has been able to map Darwin’s Heat Vulnerability Index.
This in turn has been fed into an interactive app so that urban planners, policymakers, and researchers can pinpoint concentrations of at-risk populations, and so identifying where equitable distribution of heat mitigating infrastructure can reach those more likely to lack the resources needed to cool their homes – such as the very young, the elderly, and low-income households.
Simple Solutions
Not that every solution needs to be quite so complex or a large construction project.
Although not part of DLL, the City of Darwin’s community tree planting initiative deserves a mention.
Stephen explains that the City of Darwin organises popular “tree giveaways”, where they hand out saplings for residents to plant on their property. It supports Darwin’s greening strategy, too, by helping to green private land.
Communicating Heat Mitigation
Narrowing the gap between science and everyday residents is an important part of DLL’s work.
After five years, Stephen says it can still be difficult for people to grasp the concept of a Living Lab. He is regularly contacted by those wanting to see the CSIRO research facility and has to explain that Darwin itself is the testing ground.
Lesson two: communications about the science should be simple, consistent, and clear from the start.
Although it’s due an update, the Your Tropical City web platform serves as a gateway for a general audience, translating the technical detail found on the original Darwin Living Lab website into accessible summaries.
But there is a new generation of citizens who will grow up with greater awareness of heat, it’s causes, and how to handle it.
CSIRO assists local schools with their teaching of STEM subjects, and thanks to DLL lessons relating to heat are tangible and engaging.
“We take them out, we’ll bring some heat stress sensors and thermal cameras and run an exercise with the students in thinking about how different parts of the city are hot and where they might like to see cooling.”
An Inclusive Symposium
CSIRO’s annual symposium offers another route for engagement, and it’s proactively inclusive.
They invite international experts to talk about the responses to heat performed in other cities – including, in 2025, a speaker from the Singapore National Parks Board and high profile heat and health researcher, Dr Ollie Jay. But notably, the symposium gives everyday Darwinians a chance to join in.
In what Stephen describes as “community soapbox sessions”, the people running the DLL make sure voices from diverse and “vulnerable populations”, as well as land care groups are brought in to hear the talks, pitch their own ideas, and share what they personally are already doing to cope with the heat.
This includes representatives from the Larrakia people, the traditional owners of this land.
Their intimate knowledge of the local landscape and relationship to its ecosystems have been shaped over tens of thousands of years but was largely ignored by the invasive colonial populations until quite recently.
Now in a period thankfully more characterised by healing and respect, Larrakia knowhow informs and improves contemporary urban systems, which are beginning to operate more harmoniously with nature; the symposium provides an arena where their voices can be heard and their knowledge can be shared, giving cities from far and wide the chance to learn from it.
We get good feedback, just for providing a forum for people who wouldn’t necessarily come in a room together in their day-to-day work life and discuss heat and climate adaptation and greening.
Advice from a Tropical Living Lab
With five years still to go, the data is still being gathered and crunched and is not yet ready for public consumption. But Stephen has some advice ready to go, based on anecdotal evidence at this stage, which could nevertheless be gold for similar tropical cities.
Know Your Greens!
Vegetation will only provide the best shade and atmospheric cooling it possibly can if it’s healthy.
Cities should pick species best suited to the local climate, including hostile environments like northern Australia.
And don’t forget to help greenery do its job.
A verdant tree canopy that came out of the heat mitigation trial provided a valuable lesson about Nature-based Solutions: soil vaults can be highly successful in helping vegetation establish. Root growth can often be limited due to underground infrastructure, highly compacted urban soil, and paved surfaces impacting natural water infiltration, but tree vaults allow for more natural root spread, resulting in healthy trees.
Tree canopy coverage on Cavenagh Street has now reached “four to five meters” providing a decent coverage and comfortable microclimate, but it never would have been possible without human intervention.
Life After Death
We rarely consider the lifecycle of urban forests, but Stephen explains that if we only plant a single species and all at once, they will also likely expire at roughly the same time resulting in tree canopy loss and the cooling effects associated with it.
That could expose citizens to a sudden heat surge, similar to the period directly after Cyclone Marcus decimated one-third of Darwin’s tree coverage in 2018. And, as the Focus on Darwin report makes very clear, “it can take considerable time for these areas to re-establish or increase shade”.
To prevent the canopy from suddenly disappearing, a city can:
- Diversify species with different lifespans and heights
- Introduce planting cycles so that greenery is continuously added
- Replace diseased plants before the rot spreads
Nothing Stays the Same
There is a downside to running a decade-long project, of course: some people move on before the end, taking a great deal of knowledge when they leave.
Limiting impact begins with a theory of change, “So mapping out your vision and how to get there,” Stephen explains, and making sure that every stakeholder knows what is expected of them – decision-makers, planners, academics, businesses, citizens, etc.
Extended timescales also have their advantages. Most notably, it has shown DLL how some activities “have taken longer than we would’ve liked” but it has also provided the breathing space necessary to see them through.
So, cities that are serious about testing and evaluating heat mitigation solutions need to be generous with the duration they allow themselves – it’s no quick fix!
A Global Phenomenon
Lessons from the Darwin Living Lab will resonate around the world for some time.
Our CityChanger points out that “the majority of the world’s population is going to be accommodated in tropical zones at some point in the future” – more than half of us by 2050, in fact. What Darwin learns today may assure these billions of people a much more comfortable quality of life.
Darwin can be seen as what’s coming, in a sense.
But even for cities in other climate zones, testing Nature-based Solutions in the tropics makes sense. “Things grow very quickly here,” Stephen says.
He should know – it’s science! Trees in warmer climates grow up to twice as fast as in cooler regions because of the year-long saturation of sunlight. This allows these cities to evaluate the shading effects of urban forests at an accelerated pace, much like tracking evolutionary changes across generations of short-lived fruit flies.
But for anyone for whom the science makes their head spin, Stephen’s final piece of advice is easy to swallow, and it’s relevant to everyone concerned with how they can help their heating city.
“When in doubt, plant a tree.”
Sometimes the simplest science is the most effective.