Solutions to address climate change have to begin with making our cities cleaner and more sustainable. Cities are one of the main contributors to climate change, while the impact of pollution and changes to our climate disproportionately affects cities and the billions of people who live in them.  

Few of the radical changes required to adapt to and mitigate the impact of climate change and pollution can be done without involving those who live and work in cities. Yet most have little engagement with citizens when it comes to developing climate and environmental strategies.  

Below we explore two ways the collective intelligence of citizens can help cities become more sustainable.

Using Citizen science to monitor and understand changing urban environments

Citizen Science - where non-professional volunteers contribute to scientific research is increasingly being used by citizens to document and take action on everything from air pollution to urban wildlife in their cities. 

Concerns about pollution drive many civic science efforts.  Most projects tend to focus on quantifying air or water quality, often using creative DIY monitoring tools such as the buckets for air samples developed by the Louisiana Bucket Brigade or the Smelly Maps of Pittsburgh to enable city residents to report industrial sulfur smells. These projects put data in the hands of citizens, and help communities demand action against polluters or lobby for stronger city regulations. Perhaps the most famous example of this is from Flint, Michigan where citizen scientists helped expose dangerous levels of lead in the city water supply.  

Other initiatives focus on helping citizens map a broader set of changes to their local environment. 

The ISeeChange platform, for example, allows local communities to capture data, such as photos and changes to weather, climate or wildlife they are detecting.  

The platform pairs data from contributors with remote sensing data such as satellite images, from institutions like Nasa, to detect local changes that correlate with bigger picture trends. By enabling people to track how their climate is changing over the time, the platform equips communities with the data needed to inform adaptation decisions and actions. Platform data is shared with local planners and environmental experts, such as the New Orleans' Office of Resilience and Sustainability, who use it in their work. 

Similarly, the Inaturalist City Nature Challenge engages people in mapping changes to biodiversity in cities through short ‘bio blitzes' - 3-4 day sprints where people take and analyse photos of their local wildlife. In the 2020 challenge more than 40,000 citizen scientists from 244 cities worldwide made 800,000 observations. This provides valuable city-level information about biodiversity, while getting people to engage more with nature in the city.   

Trees absorb carbon dioxide, provide shade,manage extreme rainfall and are one of the most important pieces of green urban infrastructure. 

Crowdsourcing initiatives are helping people advocate for both protecting and planting more trees cities. One example is i-tree, which lets users map and analyse health benefits of existing trees and project the positive impact of planting more trees. This data is helping city authorities and communities map their existing green infrastructure and identify where to invest in new trees.  In London, the RELEAF i-Tree Eco project led to the first ever crowdmapping of trees in the city. This data was correlated with data about pollution, hydrology, and energy use in buildings to help inform the city's Environment Strategy.  

Involving citizens in developing climate change policies / responses 

Tools, like citizen assemblies or mini publics, focus on involving citizens actively in developing climate and environment policies and strategies.  Here, a random selection of the public are gathered for a series of events to discuss and develop policy recommendations. In 2019, Camden LBC in London was one of the first local authorities to set up a climate change citizens' assembly. The assembly involved 50 randomly assembled residents (representative of the borough) for two sessions to discuss and recommend actions the council and community could take to tackle the climate crisis. The assembly's 17 proposals -  ranging from promotion of low carbon diets to investing in trees, allotments and solar panels - were all voted through by councillors. 

Elsewhere the focus has been on using citizen involvement to hold cities to account on climate change targets. In Helsinki, the city involved residents and civil society groups in drafting its ambitious action plan to make the city carbon-neutral by 2035. To continue engagement the city set up Helsinki Climate Watch - a platform where anyone can track and query progress on each of the 147 greenhouse gas reduction actions in the plan. 

There are more opportunities than ever for local government to work with people on making our cities more sustainable. In fact, being stuck at home during lockdown has increased public interest in citizen science efforts.  

Growing evidence shows that these projects could make a real difference in helping cities better adapt and respond to climate change. A recent study from the European Environmental Agency found a number of benefits in citizen science initiatives in addressing local air quality issues including improving official air quality models, informing better policy making and raising public awareness of air quality problems. 

Peter Baeck is head of the Centre for Collective Intelligence Design at Nesta and Sophie Reynolds is a researcher at Nesta