Mapping a fairer future: The open-source movement that's mobilising for climate resilience

Huge swathes of the planet barely appear on commercial maps, leaving open-source maps – built and updated by volunteers around the world – to fill in the gaps. Now, the nonprofit Humanitarian OpenStreetMap Team wants to get the software and knowhow to would-be mappers everywhere, so they can better prepare for and respond to climate-related disasters – and make a living by deploying their new skills.

When the emergency call comes in, Emilio Mariscal rushes out of his house, grabbing his gear as he goes: helmet, boots, protective clothing, backpack and spare phone with extra batteries. He doesn’t know if he’ll be gone for hours – or days.

This heavily forested area – the Sierras mountains in Córdoba province, Argentina – is prone to wildfires. When a fire is reported, it is imperative that crews like Mariscal’s can quickly locate it and pinpoint houses at risk. But, as in many forests, internet connection is patchy and even when you are online, coverage of the area by commercial maps is sparse. Satellite imagery of forested areas is often blanked out by trees, leaving roads and buildings impossible to see.

This time, they are heading to a village called Salsipuedes, 15 km from La Granja, where they are based. The Salsipuedes fire crew has called for support and Mariscal’s crew is worried — the wind is picking up and Salsipuedes is in an area known as “wildland-urban interface”, where human settlements meet forests. It’s a prime location for a wildfire and an immediate threat, not just to this village and its residents but to the surrounding forest and villages too.

The La Granja crew pulls up at the Salsipuedes fire station and Mariscal speaks to a member of their team. Her first question to him: “Do you know OsmAnd?”

An emergency might not seem like the best time for sharing tech tips. But OsmAnd is an app that allows users to access open-source maps – which anyone can edit to cover remote areas like this – even when offline.

And yes, Mariscal knows OsmAnd. In fact, he had trained the Salsipuedes fire crew in how to use the app. The woman says the village landfill is on fire, shares its location on OsmAnd, and the La Granja crew rushes off.

When they arrive at the landfill, the air is thick with smoke. The flames have moved from the edge of the landfill to the trees and are starting to spread into the forest. Because there are no large bodies of water in the Sierras and it isn’t possible to bring the fire truck nearby, the crews work together to fight the flames with rakes, shovels and Pulaskis, a specialised hand tool for wildland firefighters. Mariscal calls this “direct combat”.

Metre by metre, they push the enemy back. Eventually, the fire is extinguished. No casualties, no buildings destroyed. A disaster prevented, in no small part thanks to open-source mapping.

This fire took place in 2021, but jump to the present day and Mariscal’s journey has come full circle. He is now a software engineering manager for Humanitarian OpenStreetMap Team, known as HOT, a non-profit which creates and supports the use of open-source maps for humanitarian aid and community development. He builds software for HOT and trains communities in how to use open-source mapping tools, like OsmAnd and those made by HOT, just like the training he gave to the Salsipuedes fire crew.

For Mariscal, the pivotal role played by the OsmAnd app, and the fact that local crews could use it, is exactly what HOT is about. “That is what we want. People and communities taking ownership and using the tech, because these are not [HOT] products, it’s something that we build together,” he says.

Firefighters across the world use rakes, shovels and Pulaskis — a specialised hand tool — to fight wildfires. (Dusty J/Flickr)

Emilio Mariscal (pictured right) is a software engineering manager – and a volunteer firefighter who knows first-hand how vital accurate maps are. (Silvi Meritano/Flickr)

The journey from La Granja to Salsipuedes displayed on OpenStreetMap: a free, editable and open-source map of the world.

Better data, smarter decisions

If you want to know about risk, ask the insurance industry. Under current projections for global temperature rises, the scale of damage threatened by extreme weather is so huge that insurers will no longer be able to offer coverage and – as a board member of Allianz SE, one of the world’s biggest insurance companies, put it earlier this year – “capitalism as we know it ceases to be viable”.

Aviva has said extreme weather damages for the decade to 2023 hit US$2tn, while GallagherRE totted up US$400bn in 2024 alone. The message from insurers like these is clear: disasters like the Córdoba wildfires, the typhoon in China and Taiwan in September of this year and flooding in Pakistan throughout the 2025 monsoon season will become more frequent and more devastating.

Crucial to understanding the risk of such disasters is geospatial data — information tied to a specific location, combining geographical position with descriptive details about that site. Accurate geospatial data allows for analysis of the vulnerabilities to different risks, for example how likely flooding is in a certain community, enabling more informed decision-making on how to allocate resources.

One place where anyone can find geospatial data is OpenStreetMap, the platform that HOT’s work is based on. OpenStreetMap is like a cross between Google Maps and Wikipedia: a free, editable and open-source map of the world, maintained by a huge, global community of volunteers. Users of OpenStreetMap include sport social network Strava, Amazon delivery drivers and car park finding service Parkopedia.

From the early 2000s, OpenStreetMap volunteers had suggested it could be used in disaster relief efforts. Because maps of remote and rural areas, particularly in the Global South, are often incomplete or unavailable to the public, emergency services and aid organisations can struggle to navigate or pinpoint important locations. Maps based on imagery from before a disaster no longer depict the reality if bridges have collapsed or buildings have been destroyed.

The idea of deploying OpenStreetMap to save lives was put to the test when a 7.0 magnitude earthquake struck Haiti in 2010. Within just 48 hours, Mikel Maron, a freelance software engineer with a longstanding involvement in OpenStreetMap, had assembled a team of mapping volunteers to use up-to-date satellite imagery to trace features like buildings and roads onto OpenStreetMap data.

Within a month, hundreds of other volunteers around the world were contributing to a map which was used by the UN, Doctors Without Borders, the World Bank and US Marine Corps in their response to the disaster. The concept of using OpenStreetMap for humanitarian purposes was thoroughly proven, and HOT was formally registered in the following months.

Fifteen years on, HOT has around 75 members of staff, and provides 748,000 volunteer mappers across the world with eight open-source tools to perform functions from image gathering, to mapping, to data analysis. These volunteers collect data either remotely - using satellite or drone imagery - or in person. Any data made public is then validated by HOT volunteers or staff to ensure accuracy and completeness.

The scope of HOT’s work now is vast, taking in projects as varied as mangrove restoration in Indonesia, retrospectively mapping buildings in pre-conflict Gaza to better understand the destruction of the territory, and creating a map and database of critical emergency resources for better disaster preparedness in St. Kitts and Nevis.

HOT staff and volunteers use drone imagery — like this picture taken during a project in Brazil — to create maps which are then enriched with participatory field mapping and sometimes AI tools.

In Indonesia, HOT's Map4Mangrove project supports mangrove restoration by gathering data for monitoring, reporting and decision-making.

After the 2010 earthquake in Haiti, hundreds of volunteer mappers mobilised on OpenStreetMap to support rescue efforts. (Colin Crowley/Flickr)

HOT volunteers use satellite imagery to modify or add new data, for example identifying buildings, roads and bridges. This 'armchair mapping' can quickly cover large areas –particularly valuable when disasters hit.

Nakuru: From satellite images to community mapping – to funding for infrastructure

In 2019 there were just 32,000 buildings in Nakuru mapped on OpenStreetMap.

By 2022, thanks to HOT's AI-supported project in the city, over 1m buildings in Nakuru were mapped.

Nakuru, a city in the Rift Valley region of Kenya, is growing fast. Its population is around half a million people and is expected to surpass 1m residents by 2030. Around 35% of the population lives in informal settlements.

An extinct volcano, the Menengai Crater, sits to the city’s north, while to the south is Lake Nakuru. Both these geological features are linked to disaster risks, such as landslides and frequent flooding.

In 2022 HOT used funding from Microsoft to launch the Satellite Imagery for Social Good project in Nakuru. Using satellite imagery, AI-assisted mapping and on-the-ground participatory mapping, HOT helped city planners assess Nakuru’s drainage systems.

This map, created by HOT, shows buildings in Nakuru at risk in the case of flash floods. Nakuru city planners have used data gathered through HOT's project to develop flood mitigation strategies using the sponge city model, a nature-based solution to flooding through which a city absorbs and holds excess water in its green spaces – essentially acting like a sponge.

This map, created by HOT, shows buildings in Nakuru at risk in the case of flash floods. Nakuru city planners have used data gathered through HOT's project to develop flood mitigation strategies using the sponge city model, a nature-based solution to flooding through which a city absorbs and holds excess water in its green spaces – essentially acting like a sponge.

The geospatial data gathered by HOT showed the urgent need for a better drainage system to reduce the damage and displacement of residents caused by floods. Nakuru city authorities used that data to secure funding from the World Bank to improve infrastructure in informal settlements.

Now, HOT is supporting Nakuru city authorities to decongest the city. This includes mapping for traffic management and identifying suitable locations for creating green spaces, among other urban planning strategies.

Tabby Nyanjui, a monitoring and evaluation specialist at HOT, says part of the project’s success was down to existing technical expertise within the city authority. But that isn’t always the case.

“What we’ve been trying to work with at HOT is strengthening the systems of open map data within governments,” she says. “It’s quite a challenge. If they don’t have that capacity, then they don’t know how map data can be of benefit to them.”

Local people, local tools, open knowledge

Why are some communities and areas not adequately mapped by commercial platforms? Google Maps, and other similar products, depend on advertising. As such, wealthy areas and those with high levels of tourism, which are likely to generate more advertising revenue, are prioritised. Areas without much potential to deliver advertising revenue receive minimal coverage.

Rebecca Firth, executive director of HOT, emphasises that she sees commercial maps and HOT’s work as complementary, rather than in competition. “Commercial maps serve the areas they cover incredibly well. We’re not trying to tarnish their approach. It’s just that business model doesn’t work in a very low-income setting,” she says.

HOT is funded by a mix of philanthropic grants and contracts with governments, local authorities, development banks or other stakeholders that want to gather data for humanitarian purposes, for example an environmental NGO.

The philanthropic funding enables HOT to continue its work supporting disaster relief efforts and mapping those areas of the world overlooked or underserved by commercial mapping platforms, because, as Firth says, “there’s a justice to that data existing”.

As HOT has grown, its focus has widened: it now also partners with communities to gather data for climate mitigation and disaster risk reduction. Although remote mapping volunteers are still central to HOT’s impact, it now emphasises building community capacity to make the mapping work sustainable without its input. Clearly, this is imperative in areas prone to climate disasters, where maps need to be regularly updated.

“One of our taglines is ‘local people, local tools, open knowledge’”, says Firth. “Somebody who lives in a place, using a device that they already know, to gather data is much more sustainable than flying in somebody from Europe with a £50,000 drone for five days, who then leaves and the local computers don’t even have the processing power to use the imagery, let alone capture it again.”

HOT’s approach to data collection is very different from that of commercial maps. Standard – or “Western”, as Firth says – data collection is based on the International System of Units (millimetres, centimetres, metres, etc). Instead, HOT looks for “minimal viable data”, meaning “enough data to make a decision on whatever the local problem is”. This allows local communities to quickly generate the data they need to address a specific need.

Firth gives the example of work HOT conducted in Tanzania to support a community at risk of flooding. While trying to gather information on historic flood levels, the team heard wildly different estimates for how severe flooding had been in previous years, ranging from many metres to just a few centimetres.

This was unhelpful, so the team adopted a minimal viable data approach, and asked the community where on their own body the flood waters reached. This produced much more reliable and consistent data which enabled work to begin to reduce flood vulnerability.

HOT also works with local communities to gather “micro data”, like which parts of a town are adequately covered by shade in a heat wave – which can only be gathered by physically walking through areas and adding details to a map.

This micro data can lead to inexpensive interventions that build significant climate resilience, says Firth. “That data is the difference between a resilient life and a not-resilient life. Planting a tree is not an expensive intervention. Painting a roof is not an expensive intervention.

“There’s a huge amount of evidence that shows that accurate information does improve community resilience,” she adds. When the information is there, people respond: “It’s in their own self-interest to do that.”

"There’s a huge amount of evidence that shows that accurate information does improve community resilience" - Rebeccca Firth, executive director of HOT.

HOT partners with the National Slum Dwellers Federation to map Uganda's informal settlements, providing data for community-led projects.

In 2017, Tanzanian organisation Crowd2Map received a micro grant from HOT, which it used to train community mappers, adding 3m buildings to OpenStreetMap.

One initiative supported by Crowd2Map is the Mugumu Safe House programme, which combats female genital mutilation.

Drones for all: taking ownership of an "incredible" tool

HOT wants to reduce financial and technical barriers so communities everywhere can gather the data they need, rather than relying on technical experts or funding from afar.

Back in Argentina, Emilio Mariscal’s work on climate resilience and disaster preparedness through use of drones shows this process in action.

Using comparatively cheap drones (Mariscal estimates around US$1,000), residents, members of local government, fire crews and civil society organisations are first trained on how to use the technology to create aerial photography for mapping.

The drone-created maps are then enriched with on-the-ground participatory field mapping, like that described by Firth, sometimes supported by AI tools. They can be used for disaster preparedness or to build climate resilience.

Mariscal describes a “map use” exercise he has run in Córdoba communities prone to wildfires, like a large-scale fire drill. The community will gather to respond to an imaginary wildfire, using data they have collected about the likely source or direction of fires and which buildings are most at risk. Using the new maps on their phones, residents execute an evacuation plan while emergency services practise their response.

“The good thing about these tools is that they are open and free. If [HOT] ceased to exist some day, the tools will prevail. And once the community starts learning about these tools, they take on ownership of these tools, and they use them by themselves,” says Mariscal.

One issue is the programming of off-the-shelf drones. At the most basic level, all that’s needed is a flying camera, but many drones have in-built limitations which prevent them being compatible with HOT software.

To get around this, HOT is working on designs for drones which can be easily built from cheap components, at a total cost of US$300-400. The designs will remain, of course, open-source and freely available to anyone who wants to access them.

Although there’s an obvious technical barrier to being able to build your own drone, the advantages go beyond just saving money. Learning to pilot the drones opens up the possibility of earning money as a paid drone pilot.

Another challenge is navigating drone regulations in multiple countries. International law firm Hogan Lovells is providing pro bono support to HOT on this front. This includes providing overviews of drone regulations and working with local experts to connect HOT with civil aviation authorities.

Matthew J. Clark, counsel at Hogan Lovells and member of the firm’s uncrewed aircraft systems practice group, says: “The regulatory landscape for drones is still developing, with many countries working to enable innovation safely and securely”. But getting it right could be a game-changer. “Drones have incredible benefits, including for HOT,” Clark says.

Endgame

HOT is set to take another leap forwards, having recently joined the 100x Impact Accelerator. Based at the London School of Economics’ Marshall Institute, this supports and funds the “world’s most promising social ventures”, helping them to consider different “endgame” pathways to reach what it calls “social unicorn status” – delivering impact on a massive scale.

“[HOT] has both proven reach and a pivotal opportunity to evolve its model to deepen its influence on how billions of people adapt to climate and humanitarian challenges,” says Fan Gu, chief investment officer at the 100x Impact Accelerator.

For Firth, the direction of HOT’s business model is clear, and it mirrors the organisation’s move from remote mapping to local data.

“Over time, we’re looking to reduce our dependency on philanthropy and increase our earned revenue. My goal is to make a sustainable business model for both [HOT] and communities to gather local data,” she says.

The focus on rich, locally gathered data and building community capacity creates opportunities for entrepreneurial mappers to establish businesses that can contract mapping work locally. Firth wants to support the creation of these businesses by providing the tech, methodology and brand reputation that builds confidence in the quality of that data.

Unlike remote mapping services, domestic businesses can provide services in the local language and at a local price point, which should open up the market to more domestic buyers.

Other potential clients are international organisations such as NGOs or UN agencies. One likely challenge, however, is their typically lengthy procurement processes – something that’s exacerbated, says Firth, when decision-makers overlook the needs of SMEs.

Take the example of a government department postponing a decision on a contract because of some disruption to its own finances. “Local actors aren’t going to have a huge amount of resilience. If you’re an entrepreneur or a startup, you can’t just wait a year because somebody took a pause,” she says.

HOT is a funder itself, distributing “micro grants” to groups in more than 30 countries to implement mapping activities, improve OpenStreetMap data, develop leadership and technology skills, and help with disaster response efforts. That grantmaking role puts the funder-community dynamic at the forefront of Firth’s mind. She describes HOT as a hands-off funder: trusting grantees to make the right decisions and then getting out of the way.

“We don’t do it perfectly, but I think that type of model is absolutely critical. There’s no power without money in this world,” she says.

Despite these challenges, Firth still sees creating opportunities for others to make a living from mapping skills as one of the most effective – and ethical – ways for HOT to make a positive impact. “That’s the direction we really, really want to push, and make fly,” she says.

HOT works with local partners in Bali to train and involve the community in mapping the area, so that they can better prepare for disasters.

HOT partners with governments and NGOs – and hopes that entrepreneurial mappers can do the same, with its support. (Ronald Mwawaka/HOT)

The Dhaka Thrive project in Bangladesh used participatory mapping to gather data to help decision-makers improve sustainability and resilience in informal settlements.

Passing on mapping and tech skills to others – including young people in Cusco, Peru – is a key part of HOT's strategy.

Photos courtesy of Humanitarian OpenStreetMap Team, unless otherwise specified.

Words by David Lyons. Design by Fanny Blanquier.

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This immersive feature was produced by Pioneers Post in partnership with Hogan Lovells and HL BaSE, the firm’s impact economy practice. The story is free to read thanks to the support of Hogan Lovells.

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