IN A little over seven years’ time, Glasgow aims to become carbon neutral. The city’s residents, homes, businesses and industries will emit no more carbon into the atmosphere than can be removed from it.
A big challenge for any city seeking to achieve this goal is to know exactly where its carbon emissions – primarily in the form of carbon dioxide (CO2) – come from.
Currently, a city’s CO2 and greenhouse gas (GHG) emissions is determined by looking at consumption data – calculating how much fuel factories, households and traffic have burned in any given period – and extrapolating from there.
But in the UK, local authorities’ emissions data is published two years in arrears.
And while cities do monitor some streets for greenhouse gas emissions and other polluting gases, CO2 is generally not among them.
A pilot project headed by the University of Strathclyde in Glasgow, however, is taking steps to gain insight into this by establishing a dense network of 25 low-cost sensors to monitor CO2, along with carbon monoxide, nitrogen oxide, nitrogen dioxide, ozone and fine particles that are hazardous to health.
Such networks can provide a high-resolution picture of the levels of any of these gases and pollutants at any given moment.
Not only is this helpful for city authorities in terms of managing air quality, it can provide up-to-date information on where CO2 emissions are originating.
This is achieved through ‘inverse modelling’ – essentially taking an air sample and combining that information with other data to work out where the gas came from.
For example, atmospheric transport models can identify emissions that came from outside the city boundaries, while naturally-occurring CO2 can be separated from the man-made emissions.
The utility of such a network was illustrated last year in the city of Oakland, where scientists at the University of California at Berkeley, who are supplying the sensors to the Glasgow project, were able to record a 25% reduction in CO2 emissions in the San Francisco Bay Area. This was due to a 50% drop in road traffic during Covid lockdown orders.
This unplanned real-world experiment demonstrated that a network of sensors could quantify the contribution of traffic exhaust fumes to the city’s wider carbon emissions.
Armed with this data and insight, city leaders and policymakers would be able to identify problem areas, take action and, importantly, have a way of seeing the near-immediate impact of their decisions.
During COP26, scientists involved in the Glasgow project will present to counterparts and city leaders from across the globe at the Cities are the Key to the Climate Solution Summit, encouraging ‘town and gown’ to combine to set up their own sensor networks.
When you consider that the world’s cities produce more than 70% of global CO2 emissions, this makes them instrumental in the battle to curb emissions and keep climate change under control – even where nation states are slow to act.
With all eyes on the city for this crucial climate summit, Glasgow is setting an example for the rest of the world.
Allister Ferguson is Professor of Photonics and Co-Lead of the GEMM Initiative, at the University of Strathclyde