City leaders can use real-time data on Greenhouse Gases to help them improve air

Glasgow air-quality monitoring project aims to show policymakers how technology can help them

Glasgow - carbon neutral by 2030

The world’s cities produce more than 70% of global carbon dioxide (CO2) emissions making them instrumental to efforts to tackle climate change.

While international negotiations on legally-binding emissions targets are complex, slow and subject to geopolitics, more and more city and regional-level politicians and policymakers are committing to taking their own independent actions that will make a real difference.

Glasgow, the host city for COP26 in November, is one such city and has pledged to become carbon neutral by 2030.

The city is also the pilot site for a project which is establishing a dense network of 25 low-cost sensors that can measure greenhouse gases (GHGs) and air quality gases including CO2, carbon monoxide (CO), nitrogen oxide (NO), nitrogen dioxide (NO2), ozone (O3) and particulate matter (PM) in real-time.

Better informed policy decisions

"For the first time the City Council is going to be able to monitor real-time information on GHG emissions and provide us with a detailed picture of where carbon emissions are produced at source," says Susan Aitken, Leader of Glasgow City Council.

"What that real-time information will allow us to do is make better informed policy decisions to see the near-immediate impact of those decisions and to help measure progress against the city’s target to be carbon neutral by 2030."

Bringing 'town & gown' together

The project is being led by the University of Strathclyde as part of the Global Environmental Measurement and Monitoring Initiative (GEMM), an international project of Optica (formerly OSA and AGU).

GEMM seeks to bring ‘town and gown’ together to support scientists around the world to develop new, low-cost approaches to measuring and modelling the ongoing changes to our environment and to provide this information to regional governments to support evidence-based decision-making on climate change policies.

Other partners include Glasgow City Council; Stanford University; the University of California, Berkeley (UC Berkeley); the Met Office and the National Physical Laboratory.

The sensors are built and provided by a team at UC Berkeley led by Professor Ron Cohen, a professor of chemistry and of earth and planetary science.

Professor Cohen has been operating a network of 70 sensors across the San Francisco Bay Area for the last eight years as part of the Berkeley Environmental Air-Quality & CO2 Network (BEACO2N) project.

More about BEACO2N

BEACO2N set out to find a way to measure GHGs, including CO2, that was cheaper than the traditional air-quality monitoring stations operated by the Environmental Protection Agency in US, which can cost around $200,000 each and don’t even include CO2 sensors.

Professor Cohen’s sensor equipment – which is the size of a shoebox – cost around $8,000 to make and records levels of CO2, air-quality related gases and PM every five seconds.

The aim is to prove this technology and approach can provide data that is robust and can be used by local governments and policymakers to guide their decisions and provide near immediate feedback.

Beaco2N sensor equipment

The effects of COVID-19

An unexpected demonstration of the capability of such a network occurred when the COVID-19 pandemic struck in March 2020.

"In the normal world, atmospheric scientists don’t really get what you’d like to do in a good science experiment – a control experiment – to wave our magic wand and say 'if I took away all the cars, what would the air look like?'" says Professor Cohen.

"But when COVID-19 hit we got the chance to see what the world is like when we’re all behaving quite differently than we did before.

"When the COVID 'shelter-in-place' order began in California, almost immediately there was a tremendous reduction in CO2 emissions in the San Francisco Bay Area. Regional carbon dioxide emissions dropped by 25%, almost all of it due to a nearly 50% drop in road traffic.

"It really allowed us to test our ideas of how much of the CO2 is from industry and how much is from cars. This is what it would look like for CO2, if we electrified the vehicle fleet.

"The implication is that emissions on the roads could be changed quickly and dramatically by policy, and we have a tool to follow that relatively quickly. This is the way to know we are on track to meet our goals.

"We are making the case that this is the way to track urban CO2 in cities all over the world."

Interpreting BEACO2N's data

Collecting air samples is only one part of the picture, however. The data generated by the sensors needs to be interpreted and inverse modelling techniques used to identify the sources of CO2 samples that have been observed, since air tends to move around and mix a lot.

"Achieving that through atmospheric measurement of CO2 is challenging," says Alistair Manning of the Met Office. "A lot of observations are needed at a city level to identify where sources of CO2 are coming from, when and why.

"We have to combine atmospheric transport models – which help us understand where air is coming from – with atmospheric observations of GHGs, together with our existing knowledge of where emissions primarily come from.

"We put all these bits of knowledge together to try to triangulate to where we think emissions are actually coming from. CO2 is challenging to measure because some of it emanates from natural sources and some is generated by human activity.

"Unpicking those two is the real challenge to understanding and attributing emissions of CO2 to different sources."

Glasgow sensor network

The Glasgow sensor network is currently being set up by Professor Craig Michie and colleagues from Strathclyde’s Department of Electronic and Electrical Engineering, with the data beamed back to Professor Cohen in California. The data from the pilot project will be open to all and used as benchmarking data.

Glasgow City Council, like many cities, already monitors air pollution levels across the city for a range of common pollutants, including nitrogen dioxide (NO2) and particulate matter (PM10, PM2.5). These are the main pollutants of concern in Glasgow, with the primary source being road traffic, especially in busy city centre streets such as Hope Street, with similar changes to GHG levels were noted during COVID lockdown in the city too.

This monitoring is conducted as part of the council’s statutory obligations on air quality and does not include CO2. Like all cities across the UK, data on CO2 levels in Glasgow are based on historic consumption of fuels for traffic, power and so on, and are only made available by the UK Government two years in arrears.

The sensors are being placed on schools, with the researchers engaging with pupils on the issues around pollution and the science behind the study, adding an additional science-outreach aspect to the project.

Solving climate & emissions challenges 'absolutely vital'

Professor Allister Ferguson, co-lead of the Glasgow air quality monitoring pilot, said: "The University of Strathclyde’s participation in the GEMM Urban Air Pilot Project benefits global research, provides the city of Glasgow with a low-cost sensor network collecting real-time data on emissions of greenhouse gasses and pollution at the neighbourhood scale and demonstrates how universities, leading scientific organisations and governments can work together toward a common goal.

"Bringing scientists, sensing and data technologists, policymakers and economists together to solve these multidimensional and multisectoral climate and emissions challenges is absolutely vital. We’d love to see other cities taking this same technology and linking up with their local universities to set up their own networks and pilot programmes.

"For comparatively modest investment, cities can utilise low-cost sensors to gain an immediate tool that will allow them to manage air quality and GHG emissions in a much more informed and rapid fashion."

The technology does have real potential to help cities understand where their CO2 and other GHG emissions are coming from, but there are still challenges.

Professor Ken Alex, Director of Project Climate at the University of California, Berkeley, says: "The key barrier to implementing this kind of technological approach include getting cities and decision makers up to speed that the potential to do this exists."

Benefits for Glasgow are clear

Professor Tom Baer, Executive Director of the Stanford Photonics Research Center at Stanford University and a former President of Optica, said: "The Scientific Societies leading this initiative, Optica and American Geophysical Union, are committed to working with cities to address both the technical challenges and the budget constraints that city officials face.

"Our members are providing expert technical support on a voluntary basis and the GEMM network is actively working with cities to identify funding sources for the purchase and installation of the monitors that do not rely on traditional city revenue streams."

For city leader Susan Aitken however, the benefits of such technology for Glasgow are clear. She said: "We’re going to face an ever-increasing need for more accurate environmental data, improved measurements and forecasting models so that we can better develop the strategies and policies that we need to adapt to or mitigate the impacts of climate change.

"And GEMM will be at the absolute vanguard of how we use that environmental data in shaping a sustainable future in Glasgow."

COP 26 event: Cities are the Key to the Climate Solution

GEMM held a hybrid (online/in-person) summit during COP26 in Glasgow – Cities are the Key to the Climate Solution – on 3 November where city leaders, policymakers and scientists discussed how affordable real-time monitoring technology can help cities tackle climate change and air pollution. You can watch the seminar on Optica's YouTube channel.

Find out more & register for event